Friction stir welding and processing
Friction stir welding and processing
R.S.Mishra a ,*,Z.Y .Ma b
a Center for Friction Stir Processing,Department of Materials Science and Engineering,University of Missouri,Rolla,MO 65409,USA
b Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China
Available online 18August 2005
Abstract
Friction stir welding (FSW)is a relatively new solid-state joining process.This joining technique is energy ef?cient,environment friendly,and versatile.In particular,it can be used to join high-strength aerospace aluminum alloys and other metallic alloys that are hard to weld by conventional fusion welding.FSW is considered to be the most signi?cant development in metal joining in a decade.Recently,friction stir processing (FSP)was developed for microstructural modi?cation of metallic materials.In this review article,the current state of understanding and development of the FSW and FSP are addressed.Particular emphasis has been given to:(a)mechanisms responsible for the formation of welds and microstructural re?nement,and (b)effects of FSW/FSP parameters on resultant microstructure and ?nal mechanical properties.While the bulk of the information is related to aluminum alloys,important results are now available for other metals and alloys.At this stage,the technology diffusion has signi?cantly outpaced the fundamental understanding of microstructural evolution and microstructure–property relationships.#2005Elsevier B.V .All rights reserved.
Keywords:Friction stir welding;Friction stir processing;Weld;Processing;Microstructure
1.Introduction
The dif?culty of making high-strength,fatigue and fracture resistant welds in aerospace aluminum alloys,such as highly alloyed 2XXX and 7XXX series,has long inhibited the wide use of welding for joining aerospace structures.These aluminum alloys are generally classi?ed as non-weldable because of the poor solidi?cation microstructure and porosity in the fusion zone.Also,the loss in mechanical properties as compared to the base material is very signi?cant.These factors make the joining of these alloys by conventional welding processes unattractive.Some aluminum alloys can be resistance welded,but the surface preparation is expensive,with surface oxide being a major problem.
Friction stir welding (FSW)was invented at The Welding Institute (TWI)of UK in 1991as a solid-state joining technique,and it was initially applied to aluminum alloys [1,2].The basic concept of FSW is remarkably simple.A non-consumable rotating tool with a specially designed pin and shoulder is inserted into the abutting edges of sheets or plates to be joined and traversed along the line of joint (Fig.1).The tool serves two primary functions:(a)heating of workpiece,and (b)movement of material to produce the joint.The heating is accomplished by friction between the tool and the workpiece and plastic deformation of workpiece.The localized heating softens the material around the pin and combination of tool rotation and translation leads to movement of material from the front
of Materials Science and Engineering R 50(2005)1–78
*Corresponding author.Tel.:+15733416361;fax:+15733416934.
E-mail address:rsmishra@https://www.sodocs.net/doc/0818522058.html, (R.S.Mishra).
0927-796X/$–see front matter #2005Elsevier B.V .All rights reserved.
doi:10.1016/j.mser.2005.07.001
the pin to the back of the pin.As a result of this process a joint is produced in ‘solid state ’.Because of various geometrical features of the tool,the material movement around the pin can be quite complex
[3].During FSW process,the material undergoes intense plastic deformation at elevated temperature,resulting in generation of ?ne and equiaxed recrystallized grains [4–7].The ?ne microstructure in friction stir welds produces good mechanical properties.
FSW is considered to be the most signi ?cant development in metal joining in a decade and is a ‘‘green ’’technology due to its energy ef ?ciency,environment friendliness,and versatility.As compared to the conventional welding methods,FSW consumes considerably less energy.No cover gas or ?ux is used,thereby making the process environmentally friendly.The joining does not involve any use of ?ller metal and therefore any aluminum alloy can be joined without concern for the compatibility of composition,which is an issue in fusion welding.When desirable,dissimilar aluminum alloys and composites can be joined with equal ease [8–10].In contrast to the traditional friction welding,which is usually performed on small axisymmetric parts that can be rotated and pushed against each other to form a joint [11],friction stir welding can be applied to various types of joints like butt joints,lap joints,T butt joints,and ?llet joints [12].The key bene ?ts of FSW are summarized in Table 1.
Recently friction stir processing (FSP)was developed by Mishra et al.[13,14]as a generic tool for microstructural modi ?cation based on the basic principles of FSW.In this case,a rotating tool is inserted in a monolithic workpiece for localized microstructural modi ?cation for speci ?c property enhancement.For example,high-strain rate superplasticity was obtained in commercial 7075Al alloy 2R.S.Mishra,Z.Y.Ma /Materials Science and Engineering R 50(2005)1–
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Fig.1.Schematic drawing of friction stir welding.
Table 1
Key bene ?ts of friction stir welding
Metallurgical bene ?ts
Environmental bene ?ts Energy bene ?ts Solid phase process
Low distortion of workpiece
Good dimensional stability
and repeatability
No loss of alloying elements
Excellent metallurgical
properties in the joint area
Fine microstructure
Absence of cracking
Replace multiple parts
joined by fasteners No shielding gas required No surface cleaning required Eliminate grinding wastes Eliminate solvents required for degreasing Consumable materials saving,such as rugs,wire or any other gases Improved materials use (e.g.,joining different thickness)allows reduction in weight Only 2.5%of the energy needed for a laser weld Decreased fuel consumption in light weight aircraft,automotive and ship applications
3 R.S.Mishra,Z.Y.Ma/Materials Science and Engineering R50(2005)1–78
by FSP[13–15].Furthermore,FSP technique has been used to produce surface composite on aluminum substrate[16],homogenization of powder metallurgy aluminum alloy[17],microstructural
modi?cation of metal matrix composites[18]and property enhancement in cast aluminum alloys[19].
FSW/FSP is emerging as a very effective solid-state joining/processing technique.In a relatively
short duration after invention,quite a few successful applications of FSW have been demonstrated
[20–23].In this paper,the current state of understanding and development of the FSW and FSP are reviewed.
2.Process parameters
FSW/FSP involves complex material movement and plastic deformation.Welding parameters,
tool geometry,and joint design exert signi?cant effect on the material?ow pattern and temperature distribution,thereby in?uencing the microstructural evolution of material.In this section,a few major
factors affecting FSW/FSP process,such as tool geometry,welding parameters,joint design are addressed.
2.1.Tool geometry
Tool geometry is the most in?uential aspect of process development.The tool geometry plays a
critical role in material?ow and in turn governs the traverse rate at which FSW can be conducted.An
FSW tool consists of a shoulder and a pin as shown schematically in Fig.2.As mentioned earlier,the
tool has two primary functions:(a)localized heating,and(b)material?ow.In the initial stage of tool
plunge,the heating results primarily from the friction between pin and workpiece.Some additional
heating results from deformation of material.The tool is plunged till the shoulder touches the workpiece.The friction between the shoulder and workpiece results in the biggest component of heating.From the heating aspect,the relative size of pin and shoulder is important,and the other design
features are not critical.The shoulder also provides con?nement for the heated volume of material.
The second function of the tool is to‘stir’and‘move’the material.The uniformity of microstructure
and properties as well as process loads are governed by the tool design.Generally a concave shoulder
and threaded cylindrical pins are used.
With increasing experience and some improvement in understanding of material?ow,the tool geometry has evolved signi?https://www.sodocs.net/doc/0818522058.html,plex features have been added to alter material?ow,mixing
and reduce process loads.For example,Whorl TM and MX Tri?ute TM tools developed by TWI are
shown in Fig.3.Thomas et al.[24]pointed out that pins for both tools are shaped as a frustum that displaces less material than a cylindrical tool of the same root diameter.Typically,the Whorl TM reduces the displaced volume by about 60%,while the MX Tri ?ute TM reduces the displaced volume by about 70%.The design features of the Whorl TM and the MX Tri ?ute TM are believed to (a)reducewelding force,(b)enable easier ?ow of plasticized material,(c)facilitate the downward augering effect,and (d)increase the interface between the pin and the plasticized material,thereby increasing heat generation.It has been demonstrated that aluminum plates with a thickness of up to 50mm can be successfully friction stir welded in one pass using these two tools.A 75mm thick 6082Al-T6FSW weld was made using Whorl TM tool in two passes,each giving about 38mm penetration.Thomas et al.[24]suggested that the major factor determining the superiority of the whorl pins over the conventional cylindrical pins is the ratio of the swept volume during rotation to the volume of the pin itself,i.e.,a ratio of the ‘‘dynamic volume to the static volume ’’that is important in providing an adequate ?ow path.Typically,this ratio for pins with similar root diameters and pin length is 1.1:1for conventional cylindrical pin,1.8:1for the Whorl TM and 2.6:1for the MX Tri ?ute TM pin (when welding 25mm thick plate).
For lap welding,conventional cylindrical threaded pin resulted in excessive thinning of the top sheet,leading to signi ?cantly reduced bend properties [25].Furthermore,for lap welds,the width of the weld interface and the angle at which the notch meets the edge of the weld is also important for applications where fatigue is of main concern.Recently,two new pin geometries —Flared-Trifute TM with the ?ute lands being ?ared out (Fig.4)and A-skew TM with the pin axis being slightly inclined to the axis of machine spindle (Fig.5)were developed for improved quality of lap welding [25–27].The design features of the Flared-Trifute TM and the A-skew TM are believed to:(a)increase the ratio between of the swept volume and static volume of the pin,thereby improving the ?ow path around and underneath the pin,(b)widen the welding region due to ?ared-out ?ute lands in the Flared-Trifute TM pin and the skew action in the A-skew TM pin,(c)provide an improved mixing action for oxide fragmentation and dispersal at the weld interface,and (d)provide an orbital forging action at the root of the weld due to the skew action,improving weld quality in this https://www.sodocs.net/doc/0818522058.html,pared to the 4R.S.Mishra,Z.Y.Ma /Materials Science and Engineering R 50(2005)1–
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Fig.3.Worl TM and MX Tri ?ute TM tools developed by The Welding Institute (TWI),UK (Copyright #2001,TWI Ltd)(after Thomas et al.[24]).
conventional threaded pin,Flared-Trifute TM and A-skew TM pins resulted in:(a)over 100%improve-ment in welding speed,(b)about 20%reduction in axial force,(c)signi ?cantly widened welding region (190–195%of the plate thickness for Flared-Trifute TM and A-skew TM pins,110%for conventional threaded pin),and (d)a reduction in upper plate thinning by a factor of >4[27].Further,Flared-Trifute TM pin reduced signi ?cantly the angle of the notch upturn at the overlapping plate/weld interface,whereas A-skew TM pin produced a slight downturn at the outer regions of the overlapping plate/weld interface,which are bene ?cial to improving the properties of the FSW joints
[25,27].Thomas and Dolby [27]suggested that both Flared-Trifute TM and A-skew TM pins are suitable for lap,T,and similar welds where joining interface is vertical to the machine axis.
Further,various shoulder pro ?les were designed in TWI to suit different materials and conditions (Fig.6).These shoulder pro ?les improve the coupling between the tool shoulder and the workpieces by entrapping plasticized material within special re-entrant features.
Considering the signi ?cant effect of tool geometry on the metal ?ow,fundamental correlation between material ?ow and resultant microstructure of welds varies with each tool.A critical need is to develop systematic framework for tool https://www.sodocs.net/doc/0818522058.html,putational tools,including ?nite element analysis R.S.Mishra,Z.Y.Ma /Materials Science and Engineering R 50(2005)1–78
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Fig.4.Flared-Tri ?ute TM tools developed by The Welding Institute (TWI),UK:(a)neutral ?utes,(b)left ?utes,and (c)right hand ?utes (after Thomas et al.[25]
).
Fig.5.A-Skew TM tool developed by The Welding Institute (TWI),UK:(a)side view,(b)front view,and (c)swept region encompassed by skew action (after Thomas et al.[25]).
(FEA),can be used to visualize the material ?ow and calculate axial forces.Several companies have indicated internal R&D efforts in friction stir welding conferences,but no open literature is available on such efforts and outcome.It is important to realize that generalization of microstructural development and in ?uence of processing parameters is dif ?cult in absence of the tool information.
2.2.Welding parameters
For FSW,two parameters are very important:tool rotation rate (v ,rpm)in clockwise or counterclockwise direction and tool traverse speed (n ,mm/min)along the line of joint.The rotation of tool results in stirring and mixing of material around the rotating pin and the translation of tool moves the stirred material from the front to the back of the pin and ?nishes welding process.Higher tool rotation rates generate higher temperature because of higher friction heating and result in more intense stirring and mixing of material as will be discussed later.However,it should be noted that frictional coupling of tool surface with workpiece is going to govern the heating.So,a monotonic increase in heating with increasing tool rotation rate is not expected as the coef ?cient of friction at interface will change with increasing tool rotation rate.
In addition to the tool rotation rate and traverse speed,another important process parameter is the angle of spindle or tool tilt with respect to the workpiece surface.A suitable tilt of the spindle towards trailing direction ensures that the shoulder of the tool holds the stirred material by threaded pin and move material ef ?ciently from the front to the back of the pin.Further,the insertion depth of pin into the workpieces (also called target depth)is important for producing sound welds with smooth tool shoulders.The insertion depth of pin is associated with the pin height.When the insertion depth is too shallow,the shoulder of tool does not contact the original workpiece surface.Thus,rotating shoulder cannot move the stirred material ef ?ciently from the front to the back of the pin,resulting in generation of welds with inner channel or surface groove.When the insertion depth is too deep,the shoulder of tool plunges into the workpiece creating excessive ?ash.In this case,a signi ?cantly concave weld is produced,leading to local thinning of the welded plates.It should be noted that the recent development of ‘scrolled ’tool shoulder allows FSW with 08tool tilt.Such tools are particularly preferred for curved joints.
Preheating or cooling can also be important for some speci ?c FSW processes.For materials with high melting point such as steel and titanium or high conductivity such as copper,the heat produced by friction and stirring may be not suf ?cient to soften and plasticize the material around the rotating tool.Thus,it is dif ?cult to produce continuous defect-free weld.In these cases,preheating or additional external heating source can help the material ?ow and increase the process window.On the other hand,materials with lower melting point such as aluminum and magnesium,cooling can be used to reduce 6R.S.Mishra,Z.Y.Ma /Materials Science and Engineering R 50(2005)1–
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extensive growth of recrystallized grains and dissolution of strengthening precipitates in and around the stirred zone.
2.3.Joint design
The most convenient joint con ?gurations for FSW are butt and lap joints.A simple square butt joint is shown in Fig.7a.Two plates or sheets with same thickness are placed on a backing plate and clamped ?rmly to prevent the abutting joint faces from being forced apart.During the initial plunge of the tool,the forces are fairly large and extra care is required to ensure that plates in butt con ?guration do not separate.A rotating tool is plunged into the joint line and traversed along this line when the shoulder of the tool is in intimate contact with the surface of the plates,producing a weld along abutting line.On the other hand,for a simple lap joint,two lapped plates or sheets are clamped on a backing plate.A rotating tool is vertically plunged through the upper plate and into the lower plate and traversed along desired direction,joining the two plates (Fig.7d).Many other con ?gurations can be produced by combination of butt and lap joints.Apart from butt and lap joint con ?gurations,other types of joint designs,such as ?llet joints (Fig.7g),are also possible as needed for some engineering applications.
It is important to note that no special preparation is needed for FSW of butt and lap joints.Two clean metal plates can be easily joined together in the form of butt or lap joints without any major concern about the surface conditions of the plates.
3.Process modeling
FSW/FSP results in intense plastic deformation and temperature increase within and around the stirred zone.This results in signi ?cant microstructural evolution,including grain size,grain boundary character,dissolution and coarsening of precipitates,breakup and redistribution of dispersoids,and texture.An understanding of mechanical and thermal processes during FSW/FSP is needed for optimizing process parameters and controlling microstructure and properties of welds.In this section,the present understanding of mechanical and thermal processes during FSW/FSP is reviewed.
3.1.Metal ?ow
The material ?ow during friction stir welding is quite complex depending on the tool geometry,process parameters,and material to be welded.It is of practical importance to understand the material ?ow characteristics for optimal tool design and obtain high structural ef ?ciency welds.This has led to R.S.Mishra,Z.Y.Ma /Materials Science and Engineering R 50(2005)1–78
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Fig.7.Joint con ?gurations for friction stir welding:(a)square butt,(b)edge butt,(c)T butt joint,(d)lap joint,(e)multiple lap joint,(f)T lap joint,and (g)?llet joint.
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numerous investigations on material?ow behavior during FSW.A number of approaches,such as
tracer technique by marker,welding of dissimilar alloys/metals,have been used to visualize material
?ow pattern in FSW.In addition,some computational methods including FEA have been also used to
model the material?ow.
3.1.1.Experimental observations
The material?ow is in?uenced very signi?cantly by the tool design.Therefore,any general-ization should be treated carefully.Also,most of the studies do not report tool design and all process
conditions.Therefore,differences among various studies cannot be easily discerned.To develop an
overall pattern,in this review a few studies are speci?cally summarized and then some general trends
are presented.
3.1.1.1.Tracer technique by marker.One method of tracking the material?ow in a friction stir weld
is to use a marker material as a tracer that is different from the material being welded.In the past few
years,different marker materials,such as aluminum alloy that etch differently from the base metal
[28–30],copper foil[31],small steel shots[32,33],Al–SiC p and Al–W composites[3,34],and
tungsten wire[35],have been used to track the material?ow during FSW.
Reynolds and coworkers[28–30]investigated the material?ow behavior in FSW2195Al-T8 using a marker insert technique(MIT).In this technique,markers made of5454Al-H32were
embedded in the path of the rotating tool as shown in Fig.8and their?nal position after welding
was revealed by milling off successive slices of0.25mm thick from the top surface of the weld,
etching with Keller’s reagent,and metallographic examination.Further,a projection of the marker
positions onto a vertical plane in the welding direction was constructed.These investigations revealed
the following.First,all welds exhibited some common?ow patterns.The?ow was not symmetric
about the weld centerline.Bulk of the marker material moved to a?nal position behind its original
position and only a small amount of the material on the advancing side was moved to a?nal position in
front of its original position.The backward movement of material was limited to one pin diameter
behind its original position.Second,there is a well-de?ned interface between the advancing and
retreating sides,and the material was not really stirred across the interface during the FSW process,at
least not on a macroscopic level.Third,material was pushed downward on the advancing side and
moved toward the top at the retreating side within the pin diameter.This indicates that the‘‘stirring’’of
material occurred only at the top of the weld where the material transport was directly in?uenced by
the rotating tool shoulder that moved material from the retreating side around the pin to the advancing
R.S.Mishra,Z.Y.Ma/Materials Science and Engineering R50(2005)1–789 side.Fourth,the amount of vertical displacement of the retreating side bottom marker was inversely proportional to the weld pitch(welding speed/rotation rate,i.e.the tool advance per rotation).Fifth,the
material transport across the weld centerline increased with increasing the pin diameter at a constant
tool rotation rate and traverse speed.Based on these observations,Reynolds et al.[29,30]suggested
that the friction stir welding process can be roughly described as an in situ extrusion process wherein
the tool shoulder,the pin,the weld backing plate,and cold base metal outside the weld zone form an
‘‘extrusion chamber’’which moves relative to the workpiece.They concluded that the extrusion
around the pin combined with the stirring action at the top of the weld created within the pin diameter a secondary,vertical,circular motion around the longitudinal axis of the weld.
Guerra et al.[31]studied the material?ow of FSW6061Al by means of a faying surface tracer
and a pin frozen in place at the end of welding.For this technique,weld was made with a thin
0.1mm high-purity Cu foil along the faying surface of the weld.After a stable weld had been established,the pin rotation and specimen translation were manually stopped to produce a pin
frozen into the workpiece.Plan view and transverse metallographic sections were examined
after etching.Based on the microstructural examinations,Guerra et al.[31]concluded that the
material was moved around the pin in FSW by two processes.First,material on the advancing side
front of a weld entered into a zone that rotates and advances simultaneously with the pin.The
material in this zone was very highly deformed and sloughed off behind the pin in arc shaped features.This zone exhibited high Vicker’s microhardness of95.Second,material on the retreating
front side of the pin extruded between the rotational zone and the parent metal and in the wake of
the weld?lls in between material sloughed off from the rotational zone.This zone exhibited low
Vicker’s microhardness of35.Further,they pointed out that material near the top of the weld (approximately the upper one-third)moved under the in?uence of the shoulder rather than the
threads on the pin.
Colligan[32,33]studied the material?ow behavior during FSW of aluminum alloys by means of
steel shot tracer technique and‘‘stop action’’technique.For the steel shot tracer technique,a line of
small steel balls of0.38mm diameter were embedded along welding direction at different positions
within butt joint welds of6061Al-T6and7075Al-T6plates.After stopping welding,each weld was subsequently radiographed to reveal the distribution of the tracer material around and behind the pin.
The‘‘stop action’’technique involved terminating friction stir welding by suddenly stopping the
forward motion of the welding tool and simultaneously retracting the tool at a rate that caused the
welding tool pin to unscrew itself from the weld,leaving the material within the threads of the pin
intact and still attached to the keyhole.By sectioning the keyhole,the?ow pattern of material in the
region immediately within the threads of the welding tool was revealed.These investigations revealed
the following important observations.First,the distribution of the tracer steel shots can be divided into
two general categories:chaotical and continuous distribution.In the regions near top surface of the
weld,individual tracer elements were scattered in an erratic way within a relatively broad zone behind
the welding tool pin,i.e.,chaotical distribution.The chaotically deposited tracer steel shots had moved
to a greater depth from their original position.In other regions of the weld,the initial continuous line of
steel shots was reorientated and deposited as a roughly continuous line of steel shot behind the pin,i.e., continuous distribution.However,the tracer steel shots were found to be little closer to the upper
surface of the weld.Second,in the leading side of the keyhole,the thread form gradually developed
from curls of aluminum.The continuous downward motion of the thread relative to the forward
advance of the pin caused the material captured inside the thread space to be deposited behind the pin.
Based on these observations,Colligan[32,33]concluded that not all the material in the tool path was
actually stirred and rather a large amount of the material was simply extruded around the retreating
side of the welding tool pin and deposited behind.However,it should be pointed out that if the marker
10R.S.Mishra,Z.Y.Ma/Materials Science and Engineering R50(2005)1–78 material has different?ow strength and density,it can create uncertainty about the accuracy of the
conclusions.
London et al.[34]investigated material?ow in FSW of7050Al-T7451monitored with6061Al–30vol.%SiC p and Al–20vol.%W composite markers.The markers with a cross-section of
0.79mm?0.51mm were placed at the center on the midplane of the workpiece(MC)and at the
advancing side on the midplane(MA).In each FSW experiment,the forward progress of the tool was
stopped while in the process of spreading the marker.The distribution of marker material was
examined by metallography and X-ray.Based on experimental observations,London et al.[34]
suggested that the?ow of the marker in the FSW zone goes through the following sequence of events.
First,material ahead of the pin is signi?cantly uplifted because of the38tilt of the tool,which creates a
‘‘plowing action’’of the metal ahead of the weld.Second,following this uplift,the marker is sheared
around the periphery of the pin while at the same time it is being pushed downward in the plate because
of the action of the threads.Third,marker material is dropped off behind the pin in‘‘streaks’’which
correspond to the geometry of the threads and speci?c weld parameters used to create these welds.
Furthermore,London et al.[34]showed that the amount of material deformation in the FSW weld
depends on the locations relative to the pin.Markers on the advancing side of the weld are distributed
over a much wider region in the wake of the weld than markers that begin at the weld centerline.
3.1.1.2.Flow visualization by FSW of dissimilar materials.In addition to the tracer technique,
several studies have used friction stir welding of dissimilar metals for visualizing the complex?ow
phenomenon.Midling[35]investigated the in?uence of the welding speed on the material?ow in
welds of dissimilar aluminum alloys.He was the?rst to report on interface shapes using images of the
microstructure.However,information on?ow visualization was limited to the interface between
dissimilar alloys.
Ouyang and Kovacevic[36]examined the material?ow behavior in friction stir butting welding of2024Al to6061Al plates of12.7mm thick.Three different regions were revealed in the welded
zone.The?rst was the mechanically mixed region characterized by the relatively uniformly dispersed
particles of different alloy constituents.The second was the stirring-induced plastic?ow region
consisting of alternative vortex-like lamellae of the two aluminum alloys.The third was the unmixed
region consisting of?ne equiaxed grains of the6061Al alloy.They reported that in the welds the
contact between different layers is intimate,but the mixing is far from complete.However,the bonding
between the two aluminum alloys was complete.Further,they attributed the vortex-like structure and
alternative lamellae to the stirring action of the threaded tool,in situ extrusion,and traverse motion
along the welding direction.
Murr and co-workers[8,10,37,38]investigated the solid-state?ow visualization in friction stir butt welding of2024Al to6061Al and copper to6061Al.The material?ow was described as a
chaotic–dynamic intercalation microstructures consisting of vortex-like and swirl features.They
further suggested that the complex mixing and intercalation of dissimilar metals in FSW is essentially
the same as the microstructures characteristic of mechanically alloyed systems.On the other hand,a
recent investigation on friction stir lap welding of2195Al to6061Al revealed that there is large vertical
movement of material within the rotational zone caused by the wash and backwash of the threads[31].
Guerra et al.[31]have stated that material entering this zone followed an unwound helical trajectory
formed by the rotational motion,the vertical?ow,and the translational motion of the pin.
3.1.1.3.Microstructural observations.The idea that the FSW is likened to an extrusion process is
also supported by Krishnan[39].Krishnan[39]investigated the formation of onion rings in friction stir
welds of6061Al and7075Al alloys by using different FSW parameters.Onion rings found in the
R.S.Mishra,Z.Y.Ma/Materials Science and Engineering R50(2005)1–78
11
welded zone is a direct evidence of characteristic material transport phenomena occurring during
FSW.It was suggested that the friction stir welding process can be thought to be simply extruding one
layer of semicylinder in one rotation of the tool and a cross-sectional slice through such a set of semicylinder results in the familiar onion ring structure.On the other hand,Biallas et al.[40]suggested
that the formation of onion rings was attributed to the re?ection of material?ow approximately at the imaginary walls of the groove that would be formed in the case of regular milling of the metal.The
induced circular movement leads to circles that decrease in radii and form the tube system.In this case,
it is believed that there should be thorough mixing of material in the nugget region.Although microstructural examinations revealed an abrupt variation in grain size and/or precipitate density at
these rings[41,42],it is noted that the understanding of formation of onion rings is far from complete
and an insight into the mechanism of onion ring formation would shed light on the overall material
?ow occurring during FSW.
Recently,Ma et al.[43]conducted a study on microstructural modi?cation of cast A356via
friction stir processing.As-cast A356plates were subjected to friction stir processing by using
different tool geometries and FSP parameters.Fig.9shows the optical micrographs of as-cast A356
and FSP sample prepared using a standard threaded pin and tool rotation rate of900rpm and traverse
speed of203mm/min.The as-cast A356was characterized by coarse acicular Si particles with an
aspect ratio of up to25,coarse primary aluminum dendrites with an average size of$100m m,and
porosity of$50m m diameter(Fig.9a).The acicular Si particles were preferentially distributed along
the boundaries of the primary aluminum dendrites,i.e.,the distribution of Si particles in the as-cast
A356was not uniform.FSP resulted in a signi?cant breakup of acicular Si particles and aluminum dendrites.A uniform redistribution of the broken Si particles in the aluminum matrix was also produced.After FSP,the average aspect ratio of Si was reduced to$2.0.Further,FSP also eliminated
the porosity in the as-cast A356.Clearly,the material within the processed zone of the FSP A356 experienced intense stirring and mixing,thereby resulting in breakup of the coarse acicular Si particles
and dendrite structure and homogeneous distribution of the Si particles throughout the aluminum
matrix.Previous investigations have indicated that the extrusion at high temperature does not reduce
the high-aspect-ratio reinforcements to nearly equiaxed particles[44,45].Besides,as-extruded metal
matrix composites are usually characterized by alternative particle-rich bands and particle-free bands
[45,46].Therefore,in the case of FSP A356under the experimental conditions used,the material?ow
within the nugget zone cannot be considered as a simple extrusion process.
Fig.9.Optical micrographs showing the microstructure of as-cast and FSP A356(standard threaded pin,900rpm and
203mm/min)[43].
12R.S.Mishra,Z.Y.Ma/Materials Science and Engineering R50(2005)1–78
3.1.2.Material?ow modeling
Apart from experimental approaches,a number of studies have been carried out to model the materials?ow during FSW using different computational codes[47–53],mathematical modeling tools
[54,55],simple geometrical model[56],and metalworking model[57].These attempts were aimed at
understanding the basic physics of the material?ow occurring during FSW.
Xu et al.[47]developed two?nite element models,the slipping interface model and the frictional contact model,to simulate the FSW process.The simulation predictions of the material?ow pattern
based on these?nite element models compare qualitatively well with an experimentally measured
pattern by means of marker insert technique[29,30].
Colegrove and Shercliff[49]modeled the metal?ow around pro?led FSW tools using a two-dimensional Computational Fluid Dynamics(CFD)code,Fluent.A‘slip’model was developed,
where the interface conditions were governed by the local shear stresses.The two-dimensional
modeling resulted in the following important?ndings.First,?ow behavior obtained by the slip model
is signi?cantly different from that obtained by the common assumption of material stick.The slip
model revealed signi?cant differences in?ow with different tool shapes,which is not evident with the
conventional stick model.Second,the deformation region for the slip model is much smaller on the
advancing side than retreating side.Third,the material in the path of the pin is swept round the
retreating side of the tool.This characteristic of the model is supported by?ow visualization
experiments by London et al.[3,34]and Guerra et al.[31].Fourth,the streamlines show a bulge
behind the tool,and the dragging of material behind the pin on the advancing side.This correlated well
with previous embedded marker experiments by Reynolds and co-workers[29,30].
Smith et al.[50]and Bendzsak and Smith[51]developed a thermo-mechanical?ow model (STIR-3D).The principles of?uid mechanics were applied in this model.It assumes viscous heat
dissipation as opposed to frictional heating.This model uses tool geometry,alloy type,tool rotation
speed,tool position and travel speed as inputs and predicts the material?ow pro?les,process loads,
and thermal pro?les.It was indicated that three quite distinct?ow regimes were formed below the tool
shoulder,namely,(a)a region of rotation immediately below the shoulder where?ow occurred in the
direction of tool rotation,(b)a region where material is extruded past the rotating tool and this
occurred towards the base of the pin,and(c)a region of transition in between regions(a)and(b)where
the?ow had chaotic behavior.
Askari et al.[52]adapted a CTH code[58]that is a three-dimensional code capable of solving time-dependent equations of continuum mechanics and thermodynamics.This model predicts
important?elds like strain,strain rate and temperature distribution.The validity of the model was
veri?ed by previous marker insert technique[3,34].Goetz and Jata[53]used a two-dimensional FEM
code,DEFORM[59],to simulate material?ow in FSW of1100Al and Ti–6Al–4V alloys.Non-
isothermal simulation showed that highly localized metal?ow is likely to occur during FSW.The
movement of tracking points in these simulations shows metal?ow around the tool from one side to
the other,creating a weld.The simulations predict strain rates of2–12sà1and strains of2–5in the
zone of localized?ow.
Stewart et al.[54]proposed two models for FSW process,mixed zone model and single slip surface model.Mixed zone model assumes that the metal in the plastic zone?ows in a vortex system at
an angular velocity of the tool at the tool–metal interface and the angular velocity drops to zero at the
edge of the plastic zone.In the single slip surface model,the principal rotational slip takes place at a
contracted slip surface outside the tool–workpiece interface.It was demonstrated that using a limited
region of slip,predictions of the thermal?eld,the force and the weld region shape were in agreement
with experimental measurement.Nunes[55]developed a detailed mathematical model of wiping?ow
transfer.This model is found to have the in-built capability to describe the tracer experiments.
Recently,Arbegast[57]suggested that the resultant microstructure and metal?ow features of a friction stir weld closely resemble hot worked microstructure of typical aluminum extrusion and forging.Therefore,the FSW process can be modeled as a metalworking process in terms of?ve conventional metal working zones:(a)preheat,(b)initial deformation,(c)extrusion,(d)forging,and (e)post heat/cool down(Fig.10).In the preheat zone ahead of the pin,temperature rises due to the frictional heating of the rotating tool and adiabatic heating because of the deformation of material.The thermal properties of material and the traverse speed of the tool govern the extent and heating rate of this zone.As the tool moves forward,an initial deformation zone forms when material is heated to above a critical temperature and the magnitude of stress exceeds the critical?ow stress of the material, resulting in material?ow.The material in this zone is forced both upwards into the shoulder zone and downwards into the extrusion zone,as shown in Fig.10.A small amount of material is captured in the swirl zone beneath the pin tip where a vortex?ow pattern exists.In the extrusion zone with a?nite width,material?ows around the pin from the front to the rear.A critical isotherm on each side of the tool de?nes the width of the extrusion zone where the magnitudes of stress and temperature are insuf?cient to allow metal?ow.Following the extrusion zone is the forging zone where the material from the front of the tool is forced into the cavity left by the forward moving pin under hydrostatic pressure conditions.The shoulder of the tool helps to constrain material in this cavity and also applies a downward forging force.Material from shoulder zone is dragged across the joint from the retreating side toward the advancing side.Behind the forging zone is the post heat/cool zone where the material cools under either passive or forced cooling conditions.Arbegast[57]developed a simple approach to metal?ow modeling of the extrusion zone using mass balance considerations that reveals a relationship between tool geometry,operating parameters,and?ow stress of the materials being joined.It was indicated that the calculated temperature,width of the extrusion zone,strain rate,and extrusion pressure are consistent with experimental observations.
In summary,the material?ow during FSW is complicated and the understanding of deformation process is limited.It is important to point out that there are many factors that can in?uence the material ?ow during FSW.These factors include tool geometry(pin and shoulder design,relative dimensions of pin and shoulder),welding parameters(tool rotation rate and direction,i.e.,clockwise or counter-clockwise,traverse speed,plunge depth,spindle angle),material types,workpiece temperature,etc.It is very likely that the material?ow within the nugget during FSW consists of several independent deformation processes.
R.S.Mishra,Z.Y.Ma/Materials Science and Engineering R50(2005)1–78
13
Fig.10.(a)Metal?ow patterns and(b)metallurgical processing zones developed during friction stir welding(after Arbegast [57]).
3.2.Temperature distribution
FSW results in intense plastic deformation around rotating tool and friction between tool and workpieces.Both these factors contribute to the temperature increase within and around the stirred zone.Since the temperature distribution within and around the stirred zone directly in ?uences the microstructure of the welds,such as grain size,grain boundary character,coarsening and dissolution of precipitates,and resultant mechanical properties of the welds,it is important to obtain information about temperature distribution during FSW.However,temperature measurements within the stirred zone are very dif ?cult due to the intense plastic deformation produced by the rotation and translation of tool.Therefore,the maximum temperatures within the stirred zone during FSW have been either estimated from the microstructure of the weld [4,5,60]or recorded by embedding thermocouple in the regions adjacent to the rotating pin [41,61–63].
An investigation of microstructural evolution in 7075Al-T651during FSW by Rhodes et al.[4]showed dissolution of larger precipitates and reprecipitation in the weld center.Therefore,they concluded that maximum process temperatures are between about 400and 4808C in an FSW 7075Al-T651.On the hand,Murr and co-workers [5,60]indicated that some of the precipitates were not dissolved during welding and suggested that the temperature rises to roughly 4008C in an FSW 6061Al.Recently,Sato et al.[61]studied the microstructural evolution of 6063Al during FSW using transmission electron microscopy (TEM)and compared it with that of simulated weld thermal cycles.They reported that the precipitates within the weld region (0–8.5mm from weld center)were completely dissolved into aluminum matrix.By comparing with the microstructures of simulated weld thermal cycles at different peak temperatures,they concluded that the regions 0–8.5,10,12.5,and 15mm away from the friction stir weld center were heated to temperatures higher than 402,353,3028C and lower than 2018C,respectively.
Recently,Mahoney et al.[41]conducted friction stir welding of 6.35mm thick 7075Al-T651plate and measured the temperature distribution around the stirred zone both as a function of distance from the stirred zone and through the thickness of the sheet.Fig.11shows the peak temperature distribution adjacent to the stirred zone.Fig.11reveals three important observations.First,maximum temperature was recorded at the locations close to the stirred zone,i.e.,the edge of the stirred zone,and the temperature decreased with increasing distance from the stirred zone.Second,the temperature at 14R.S.Mishra,Z.Y.Ma /Materials Science and Engineering R 50(2005)1–
78
Fig.11.Peak temperature distribution adjacent to a friction stir weld in 7075Al-T651.The line on the right side of ?gure shows the nugget boundary (after Mahoney et al.[41]).
15 R.S.Mishra,Z.Y.Ma/Materials Science and Engineering R50(2005)1–78
the edge of the stirred zone increased from the bottom surface of the plate to the top surface.Third,a maximum temperature of4758C was recorded near the corner between the edge of the stirred zone
and the top surface.This temperature is believed to exceed the solution temperature for the hardening precipitates in7075Al-T651[64–66].Based on these results the temperature within the stirred zone is
likely to be above4758C.However,the maximum temperature within the stirred zone should be lower
than the melting point of7075Al because no evidence of material melting was observed in the weld
[4,41].
More recently,an attempt was made by Tang et al.[62]to measure the heat input and temperature distribution within friction stir weld by embedding thermocouples in the region to be welded.6061Al-
T6aluminum plates with a thickness of6.4mm were used.They embedded thermocouples in a series
of small holes of0.92mm diameter at different distances from weld seam drilled into the back surface
of the workpiece.Three depths of holes(1.59,3.18,and4.76mm)were used to measure the temperature?eld at one quarter,one half,and three quarter of the plate thickness.They reported that
the thermocouple at the weld center was not destroyed by the pin during welding but did change
position slightly due to plastic?ow of material ahead of the pin[62].Fig.12shows the variation of the
peak temperature with the distance from the weld centerline for various depths below the top surface.
Three important observations can be made from this plot.First,maximum peak temperature was
recorded at the weld center and with increasing distance from the weld centerline,the peak temperature decreased.At a tool rotation rate of400rpm and a traverse speed of122mm/min,a
peak temperature of$4508C was observed at the weld center one quarter from top surface.Second,
there is a nearly isothermal region$4mm from the weld centerline.Third,the peak temperature
gradient in the thickness direction of the welded joint is very small within the stirred zone and between
25and408C in the region away from the stirred zone.This indicates that the temperature distribution
within the stirred zone is relatively uniform.Tang et al.[62]further investigated the effect of weld
pressure and tool rotation rate on the temperature?eld of the weld zone.It was reported that increasing
both tool rotation rate and weld pressure resulted in an increase in the weld temperature.Fig.13shows
the effect of tool rotation rate on the peak temperature as a function of distance from the weld centerline.Clearly,within the weld zone the peak temperature increased by almost408C with increasing tool rotation rate from300to650rpm,whereas it only increased by208C when the tool
rotation rate increased from650to1000rpm,i.e.,the rate of temperature increase is lower at higher
tool rotation rates.Furthermore,Tang et al.[62]studied the effect of shoulder on the temperature ?eld by using two tools with and without pin.The shoulder dominated the heat generation during FSW (Fig.14).This was attributed to the fact that the contact area and vertical pressure between the shoulder and workpiece is much larger than those between the pin and workpiece,and the shoulder has higher linear velocity than the pin with smaller radius [62].Additionally,Tang et al.[62]showed that the thermocouples placed at equal distances from the weld seam but on opposite sides of the weld showed no signi ?cant differences in the temperature.
Similarly,Kwon et al.[63],Sato et al.[67],and Hashimoto et al.[68]also measured the temperature rise in the weld zone by embedding thermocouples in the regions adjacent to the rotating pin.Kwon et al.[63]reported that in FSW 1050Al,the peak temperature in the FSP zone increased linearly from 190to 3108C with increasing tool rotation rate from 560to 1840rpm at a constant tool traverse speed of 155mm/min.An investigation by Sato et al.[67]indicated that in FSW 6063Al,the peak temperature of FSW thermal cycle increased sharply with increasing tool rotation rate from 80016R.S.Mishra,Z.Y.Ma /Materials Science and Engineering R 50(2005)1–
78
Fig.13.Effect of tool rotation rate on peak temperature as a function of distance from weld centerline for a 6061Al-T6FSW weld made at 120mm/min traverse speed (after Tang et al.[62]
).
Fig.14.Variation of peak temperature with distance from weld centerline for a 6061Al-T6FSW weld made with and without pin (400rpm and 120mm/min traverse speed)(after Tang et al.[62]).
to2000rpm at a constant tool traverse speed of360mm/min,and above2000rpm,however,it rose gradually with increasing rotation rate from2000to3600rpm.Peak temperature of>5008C was recorded at a high tool rotation rate of3600rpm.Hashimoto et al.[68]reported that the peak temperature in the weld zone increases with increasing the ratio of tool rotation rate/traverse speed for FSW of2024Al-T6,5083Al-O and7075Al-T6(Fig.15).A peak temperature>5508C was observed in FSW5083Al-O at a high ratio of tool rotation rate/traverse speed.
In a recent investigation,a numerical three-dimensional heat?ow model for friction stir welding of age hardenable aluminum alloy has been developed by Frigaad et al.[69],based on the method of ?nite differences.The average heat input per unit area and time according to their model is[69]: q0?43p2m P v R3;(1) where q0is the net power(W),m the friction coef?cient,P the pressure(Pa),v the tool rotational speed (rot/s)and R is the tool radius(m).Frigaad et al.[69]suggested that the tool rotation rate and shoulder radius are the main process variables in FSW,and the pressure P cannot exceed the actual?ow stress of the material at the operating temperature if a sound weld without depressions is to be obtained.The process model was compared with in situ thermocouple measurements in and around the FSW zone. FSW of6082Al-T6and7108Al-T79was performed at constant tool rotation rate of1500rpm and a constant welding force of7000N,at three welding speeds of300,480,and720mm/min.They revealed three important observations.First,peak temperature of above$5008C was recorded in the FSW zone.Second,peak temperature decreased with increasing traverse speeds from300to720mm/ min.Third,the three-dimensional numerical heat?ow model yields a temperature–time pattern that is consistent with that observed experimentally.Similarly,three-dimensional thermal model based on ?nite element analysis developed by Chao and Qi[70]and Khandkar and Khan[71]also showed reasonably good match between the simulated temperature pro?les and experimental data for both butt and overlap FSW processes.
The effect of FSW parameters on temperature was further examined by Arbegast and Hartley [72].They reported that for a given tool geometry and depth of penetration,the maximum temperature was observed to be a strong function of the rotation rate(v,rpm)while the rate of heating was a strong function of the traverse speed(n,rpm).It was also noted that there was a slightly higher temperature on the advancing side of the joint where the tangential velocity vector direction was same as the forward R.S.Mishra,Z.Y.Ma/Materials Science and Engineering R50(2005)1–78
17
Fig.15.Effect of tool rotation rate/traverse speed(v/n)ratio on peak temperature of FSW2024Al-T6,5083Al-O,and 7075Al-T6(after Hashimoto et al.[68]).
velocity vector.They measured the average maximum temperature on6.35mm aluminum plates as a function of the pseudo-‘‘heat index wew?v2=nT’’.It was demonstrated that for several aluminum alloys a general relationship between maximum welding temperature(T,8C)and FSW parameters(v, n)can be explained by
T T m ?K
v2
n?104
a
;(2)
where the exponent a was reported to range from0.04to0.06,the constant K is between0.65and0.75, and T m(8C)is the melting point of the alloy.The maximum temperature observed during FSW of various aluminum alloys is found to be between0.6T m and0.9T m,which is within the hot working temperature range for those aluminum alloys.Furthermore,the temperature range is generally within the solution heat-treatment temperature range of precipitation-strengthened aluminum alloys.
Recently,Schmidt et al.[73]have developed an analytical model for the heat generation in FSW. The important difference between this model and the previous models is the choice of sticking and sliding contact conditions.The expressions for total heat generation for sticking,sliding,and partial sliding/sticking conditions,respectively,are
Q total;sticking?2
3
p
s yield
???
3
p veeR3shoulderàR3probeTe1ttan aTtR3probet3R2probe H probeT;(3a)
Q total;sliding?2
3
pm p veeR3shoulderàR3probeTe1ttan aTtR3probet3R2probe H probeT;(3b)
Q total?2
3
p d
s yield
???
3
pt1àd
eTm p
veeR3shoulderàR3probeTe1ttan aTtR3probe
t3R2probe H probeT;(3c)
where Q is the total heat generation(W),s yield the yield strength(Pa),v the tool angular rotation
rate(rad/s),R shoulder the tool shoulder radius(m),R probe the tool probe radius(m),a the tool
shoulder cone angle(8),H probe the tool probe height(m),p the contact pressure(Pa),and d is the
contact state variable.Schmidt et al.[73]veri?ed the model using2024Al-T3alloy.They noted that
the analytical heat generation estimate correlates with the experimental heat generation.The
experimental heat generation was not proportional to the experimental plunge force.Based on this
they suggested that sticking condition must be present at the tool/matrix interface.It should be
noted,however,that the experiments were only performed at a rotational rate of400rpm and a
welding speed of120mm/min.
In summary,many factors in?uence the thermal pro?les during FSW.From numerous experi-mental investigations and process modeling,we conclude the following.First,maximum temperature
rise within the weld zone is below the melting point of aluminum.Second,tool shoulder dominates
heat generation during FSW.Third,maximum temperature increases with increasing tool rotation rate
at a constant tool traverse speed and decreases with increasing traverse speed at a constant tool rotation
rate.Furthermore,maximum temperature during FSW increases with increasing the ratio of tool
rotation rate/traverse speed.Fourth,maximum temperature rise occurs at the top surface of weld zone.
Various theoretical or empirical models proposed so far present different pseudo-heat index.The
experimental veri?cation of these models is very limited and attempts to correlate various data sets 18R.S.Mishra,Z.Y.Ma/Materials Science and Engineering R50(2005)1–78
with models for this review did not show any general trend.The overall picture includes frictional heating and adiabatic heating.The frictional heating depends on the surface velocity and frictional coupling (coef ?cient of friction).Therefore,the temperature generation should increase from center of the tool shoulder to the edge of the tool shoulder.The pin should also provide some frictional heating and this aspect has been captured in the model of Schmidt et al.[73].In addition,the adiabatic heating is likely to be maximum at the pin and tool shoulder surface and decrease away from the interface.Currently,the theoretical models do not integrate all these contributions.Recently,Sharma and Mishra
[74]have observed that the nugget area changes with pseudo-heat index (Fig.16).The results indicate that the frictional condition change from ‘stick ’at lower tool rotation rates to ‘stick/slip ’at higher tool rotation rates.The implications are very important and needs to be captured in theoretical and computational modeling of heat generation.
4.Microstructural evolution
The contribution of intense plastic deformation and high-temperature exposure within the stirred zone during FSW/FSP results in recrystallization and development of texture within the stirred zone
[7,8,10,15,41,62,63,75–91]and precipitate dissolution and coarsening within and around the stirred zone [8,10,41,62,63].Based on microstructural characterization of grains and precipitates,three distinct zones,stirred (nugget)zone,thermo-mechanically affected zone (TMAZ),and heat-affected zone (HAZ),have been identi ?ed as shown in Fig.17.The microstructural changes in various zones R.S.Mishra,Z.Y.Ma /Materials Science and Engineering R 50(2005)1–78
19
Fig.17.A typical macrograph showing various microstructural zones in FSP 7075Al-T651(standard threaded pin,400rpm and 51mm/min).
have signi ?cant effect on postweld mechanical properties.Therefore,the microstructural evolution during FSW/FSP has been studied by a number of investigators.
4.1.Nugget zone
Intense plastic deformation and frictional heating during FSW/FSP result in generation of a recrystallized ?ne-grained microstructure within stirred zone.This region is usually referred to as nugget zone (or weld nugget)or dynamically recrystallized zone (DXZ).Under some FSW/FSP conditions,onion ring structure was observed in the nugget zone (Figs.17and 18b).In the interior of the recrystallized grains,usually there is low dislocation density [4,5].However,some investigators reported that the small recrystallized grains of the nugget zone contain high density of sub-boundaries
[61],subgrains [75],and dislocations [92].The interface between the recrystallized nugget zone and the parent metal is relatively diffuse on the retreating side of the tool,but quite sharp on the advancing side of the tool [93].
4.1.1.Shape of nugget zone
Depending on processing parameter,tool geometry,temperature of workpiece,and thermal conductivity of the material,various shapes of nugget zone have been observed.Basically,nugget zone can be classi ?ed into two types,basin-shaped nugget that widens near the upper surface and elliptical nugget.Sato et al.[61]reported the formation of basin-shaped nugget on friction stir welding of 6063Al-T5plate.They suggested that the upper surface experiences extreme deformation and frictional heating by contact with a cylindrical-tool shoulder during FSW,thereby resulting in generation of basin-shaped nugget zone.On the other hand,Rhodes et al.[4]and Mahoney et al.
[41]reported elliptical nugget zone in the weld of 7075Al-T651.
Recently,an investigation was conducted on the effect of FSP parameter on the microstructure and properties of cast A356[94].The results indicated that lower tool rotation rate of 300–500rpm resulted in generation of basin-shaped nugget zone,whereas elliptical nugget zone was observed by FSP at higher tool rotation of >700rpm (Fig.18).This indicates that with same tool geometry,different nugget shapes can be produced by changing processing parameters.
Reynolds [29]investigated the relationship between nugget size and pin size.It was reported that the nugget zone was slightly larger than the pin diameter,except at the bottom of the weld where the pin tapered to a hemispherical termination (Fig.19).Further,it was revealed that as the pin diameter increases,the nugget acquired a more rounded shape with a maximum diameter in the middle of the weld.
4.1.2.Grain size
It is well accepted that the dynamic recrystallization during FSW/FSP results in generation of ?ne and equiaxed grains in the nugget zone [7,8,10,15,41,62,63,75–91].FSW/FSP parameters,tool geometry,composition of workpiece,temperature of the workpiece,vertical pressure,and active cooling exert signi ?cant in ?uence on the size of the recrystallized grains in the FSW/FSP materials.20R.S.Mishra,Z.Y.Ma /Materials Science and Engineering R 50(2005)1–
78
Fig.18.Effect of processing parameter on nugget shape in FSP A356:(a)300rpm,51mm/min and (b)900rpm,203mm/min (standard threaded pin)[94].
钢筋手工电弧焊
钢筋手工电弧焊 1.1 本工艺标准适用于工业与民用建筑的钢筋及埋件手工电弧焊。 2.1 材料及主要机具： 2.1.1 钢筋：钢筋的级别、直径必须符合设计要求，有出厂证明书及复试报告单。进口钢筋还应有化学复试单，其化学成分应满足焊接要求，并应有可焊性试验。预埋件的锚爪应用Ⅰ、Ⅱ级钢筋。钢筋应无老锈和油污。 2.1.2 钢材：预埋件的钢材不得有裂缝、锈蚀、斑痕、变形，其断面尺寸和机械性能应符合设计要求。 2.1.3 焊条：焊条的牌号应符合设计规定。如设计无规定时，应符合表4-14的要求，焊条质量应符合以下要求： 钢筋电弧焊使用的焊条牌号 表4-14 项次钢筋级别搭接焊、帮条焊坡口焊 1 Ⅰ级E4303 E4303 E4303 2 Ⅱ级E430 3 E4303 E5003 3 Ⅲ级E5003 E5003 E5503 4 Ⅰ、Ⅱ级与钢板焊接E4303 注：不含25MnSi钢筋。 药皮应无裂缝、气孔、凹凸不平等缺陷，并不得有肉眼看得出的偏心度。 焊接过程中，电弧应燃烧稳定，药皮熔化均匀，无成块脱落现
象。 焊条必须根据焊条说明书的要求烘干后才能使用。 焊条必须有出厂合格证。 2.1.4 弧焊机、焊接电缆、电焊钳、面罩、堑子、钢丝刷、锉刀、榔头、钢字码等。 2.2 作业条件： 2.2.1 焊工必须持有考试合格证。 2.2.2 帮条尺寸、坡口角度、钢筋端头间隙、接头位置以及钢筋轴线应符合规定。 2.2.3 电源应符合要求。 2.2.4 作业场地要有安全防护设施、防火和必要的通风措施，防止发生烧伤、触电、中毒及火灾等事故。 2.2.5 熟悉图纸，做好技术交流。 3.1 工艺流程： 检查设备→选择焊接参数→试焊作模拟试件→送试→确定焊接参数→施焊→质量检验 3.2 检查电源、焊机及工具。焊接地线应与钢筋接触良好，防止因起弧而烧伤钢筋。 3.3 选择焊接参数。根据钢筋级别、直径、接头型式和焊接位置，选择适宜的焊条直径、焊接层数和焊接电流，保证焊缝与钢筋熔合良好。 3.4 试焊、做模拟试件。在每批钢筋正式焊接前，应焊接3个
常用专业术语英文
组装、冲压、喷漆等专业词汇 Assembly line组装线 Layout布置图 OOBA开箱检查 fit together组装在一起 fasten锁紧(螺丝) fixture 夹具(治具) pallet栈板 barcode条码 barcode scanner条码扫描器 fuse together熔合 repair修理 operator作业员 QC quality品管 supervisor 课长 section supervisor课长 deputy section supervisor =vice section superisor副课长 ME制造工程师 MT制造生技 cosmetic inspect外观检查 inner parts inspect内部检查 thumb screw大头螺丝 lbs. inch镑、英寸 front plate前板 rear plate后板 chassis基座 bezel panel面板 power button电源按键 reset button重置键Hi-pot test of SPS高源高压测试 V oltage switch of SPS 电源电压接拉键 sheet metal parts 冲件 plastic parts塑胶件 SOP制造作业程序 material check list物料检查表 trolley台车 carton纸箱 sub-line支线 left fork叉车 personnel resource department 人力资源部 production department生产部门 planning department企划部 QC Section品管科 stamping factory冲压厂 painting factory烤漆厂 molding factory成型厂 punching machine 冲床 robot机械手 lathe车床 planer |'plein|刨床 miller铣床 grinder磨床 driller??床 linear cutting线切割 electrical sparkle电火花 welder电焊机 staker=reviting machine铆合机 position职务 president董事长 general manager总经理 special assistant manager特助 factory director厂长 department director部长 deputy manager | =vice manager副理 group leader/supervisor组长 line supervisor线长 thickness gauge厚薄规 gauge(or jig)治具 power wire电源线 buzzle蜂鸣器 defective product label不良标签 identifying sheet list标示单 iudustrial alcohol工业酒精 Tiana天那水 packaging打包 missing part漏件 wrong part错件 excessive defects过多的缺陷 critical defect极严重缺陷 major defect主要缺陷 minor defect次要缺陷 not up to standard不合规格 dimension/size is a little bigger尺寸偏 大(小) cosmetic defect外观不良 slipped screwhead/slippery screw head 螺丝滑头 speckle斑点 rust生锈 deformation变形 burr(金属)flash(塑件)毛边 poor staking铆合不良 excesssive gap间隙过大 grease/oil stains油污 inclusion杂质 painting peel off脏污 shrinking/shrinkage缩水 mixed color杂色 scratch划伤 poor processing 制程不良 poor incoming part事件不良 painting make-up补漆 discoloration羿色 water spots水渍 polishing/surface processing表面处理 exposed metal/bare metal金属裸露 lack of painting烤漆不到位 safety安全 quality品质 delivery deadline交货期 cost成本 engineering工程 die repair模修 enterprise plan = enterprise expansion projects企划 qualified products, up-to-grade products良品 defective products, not up-to-grade products不良品 to return material/stock to退料 scraped |'skræpid|报废 (be)qualfied, up to grade合格 not up to grade, not qualified不合格
社会学专业词汇中英文对照
（按中文拼音首字母排序） B 暴民：mob 比拟法：analogical method 比例抽样：proportionate sample 不可知论：agnosticism 变态心理学：abnormal psychology 不完全归纳：incomplete induction 边际效用递减：law of diminishing marginal utility 柏拉图式爱情：Platonic love C 丛众：conformity 残疾人：the handicapped 参考书目：bibliography 参考群体：reference group 成人教育：adult education 初婚年龄：age at first marriage 垂直流动：vertical mobility 出身群体：descent group 抽样误差：sampling error 抽样范围：sampling frame 参与式观察：participant observation D 代沟：generation gap 对照分析：contrastive analysis 定性分析：qualititive analysis 定量分析：quantitative analysis 定额抽样：quota sample 多重人格：multiple personality 地位流动：status mobility 第一手资料：primary data 第二手资料：raw data 单因素实验：single-factor experiment 地域性流动：geographical mobility F 法人：fictitions person 反隔离：desegregation 犯罪学：criminology 父居家庭：patrilocal family 父系亲属：agnate 父子关系：filiation 分析性研究：analytical research 封闭式监管：close custody 封闭型问题：closed question 分层随机抽样：stratified random sample G 规范：norms 更年期：menopause 过激主义：ultraism 个案研究：case study 个人主义：individualism 归属需求：need to belong 个人崇拜：personality cult 功能主义：functionalism H 行话，黑话：argot 横坐标：abscissa 合理趋势：rational trend 霍桑效应：Hawthorne effect 婚姻调适：marriage adjustment 宏观分析：macroscopic analysis 黄金分割：golden section 互补角色：complementary role J 家谱：family religrees 截点：cut-off point 拒答率：refusal rate 绝对值：absolute value 监护人：chaperonage 角色冲突：role conflict 角色距离：role distance 角色紧张：role strain 金钱崇拜：mammon worship 间接暗示：indirect suggestion 价值中立：value free 价值判断：value judgement
焊条电弧焊原理及特点教案
课程焊接班级任课教师
教学过程 （一）焊接电弧 定义：由焊接电源（焊机）供给的，具有一定电压的两电极间或电极与焊件之间，在气体介质中产生的强烈而持久的放电现象，称为焊接电弧。 （一）焊接电弧的特点 1、它能发出强烈的光和大量的热。 2、由于是气体在导电，它是柔性的，是可以移动的。 3、因具有柔性可以在一定长度内变化（10）毫米左右，过长就会熄灭。 到目前为止，电弧焊接方法仍然占据着主要地位，一个重要的原因就是因为电弧能够有效地，把电能转换成熔化焊接过程中所需要的热能。 （三）焊接电弧及电弧温度的分布。 注；阴极区与阳极区的 温度差别，只有使用直 流焊机时才会发生变 化，使用交流焊机时因 无阴阳极之分，焊条和 工件的温度是一样高的。因此在使用直流焊机时为了获得不同的温度就产生了极学生活动和补充内容
住脱离不开铁板，也产生不了电弧。 见擦划法图：引弧过程的运动轨迹。 操作 方 法：握 稳焊 钳，手 腕稍用力进行擦划。当焊条端头接触铁板一瞬间立即提离铁板4mm 左右电弧就会燃烧，擦划即要有一定力度，又要控制在较小长度范围内，因为一旦引燃电弧就必须停下，如继续离开铁板过高电弧将会熄灭，这就需要控制擦划时的惯力运动。因此引燃电弧的位置不具有确定性。 提示：图中标示的2-4mm是指正常焊接的电弧长度，而并非引弧长度。就一般来讲性能稍好的焊机引弧时提离铁板6mm 左右也能正常起弧。 2、敲击引弧法 敲击引弧法特点：1、引弧点准确。2、不污染工件。3、常用于焊件空间狭窄的地方。4、常用于焊缝与焊缝相连的接
头引弧。5、灭弧后立即再引弧、 敲击引弧 要领：握稳 焊钳，用腕力 向下敲击，如 用力过大则 反弹力太大，焊条端头远离铁板,电弧即燃即灭；如用力太小焊条端头易被铁板粘住。因此敲击时用力要合适，并利用好反弹力，见到弧光时立即稳住，维持电弧正常燃烧距离。 如发生焊条粘在铁板上，可左右摇摆焊条使其脱离后重新引弧。 第三种引弧方法 但通过多年的操作观察，证实它确实存在。（暂称为热引弧法） 方法是：当焊条正常燃烧3秒左右，灭弧后立即移往其他待焊部位（不超过2秒），此时焊条一触即燃（既不擦划也不敲击）。 此方法用途非常广泛，实用意义大，效果好。例如1、当我们点焊薄件或特小工件时要求是稳、准、快。稳指电弧稳定燃烧；准指被焊位置准确；快指着焊时间短（一秒左右）。2、灭弧立焊时或焊管接头时，要求再引弧位子非常准确，引弧灭弧
手工电弧焊焊接工艺
手工电弧焊焊接工艺 适用范围：本工艺适用于钢结构制作与安装手工电弧焊焊接工艺。工艺规定了一般低碳钢、普通低合金钢的手工电弧焊的基本要求。凡各工程的工艺中无特殊要求的结构件的手工电弧焊均应按本工艺规定执行。 第一节材料要求 5.1.1钢材应按施工图的要求选用，其性能和质量必须符合国家标准和行业标准的规定，并应具有质量证明书或检验报告。如果用其它钢材和焊材代换时，须经设计单位同意，并按相应工艺文件施焊。 5.1.2焊条选用原则 1.符合使用要求，焊缝金属的性能要符合使用要求（达到设计要求），一般要求焊缝金属的力学性 能，包括抗拉强度，塑性和冲击韧性达到母材金属标准规定的性能指标的下限值。 2.尽量降低成本，尽量选用生产率高成本低的焊条，即“低成本”原则。 3.结构钢焊条的选择 1）根据母材的抗拉强度，按照“等强”原则选择抗拉强度级别相同的焊条。由于熔敷金属的抗拉强度比焊条牌号的名义强度高不少，在焊接高强钢时因母材熔入影响，焊缝金属实际抗拉强度比焊条牌号的名义强度高得多。因此，可以选用抗拉强度低一等级的焊条，使焊缝金属与母材实际等强。 2）对于易裂的母材或结构(碳当量较高或工作厚度大、结构刚性大、施焊环境温度低)，对于塑性、韧性要求高的重要结构，应选用塑性韧性好、含氢量低及抗裂性能好的碱性焊条(即低氢焊条)。最好选用高韧性、超低氢焊条，以提高接头的抗冷裂性能。 3）对于管道焊接、立向下焊接、底层焊缝、盖面焊缝等，最好相应选用管道焊接专用焊条、立向下焊条、底层焊条和盖面焊条等。 4）应选用碱性焊条(即低氢焊条)而无直流焊接电源时，可选用低氢钾型焊条。 5）对于接头由不同强度的钢材组成，则按强度较低的钢材选用焊条。 6）大型结构，可选用熔敷速度较高的铁粉焊条。 4.铸铁焊条的选择 根据铸铁种类、工件的使用要求和加工要求等，选择符合要求的成本低的铸铁焊条。 5.焊件坡口形式的选择
专业术语中英文对照表
语文课程与教学论 名词术语中英文对照表 the Chinese Course and Teaching and Learning Theory in Chinese and English Teaching materials editing teaching materials /Chinese Teaching Materials /edit teaching materials /Uniformed Chinese Teaching Materials /Experimental Teaching Materials /Mother Tongue Teaching Materials /Teaching Materials of the New Course *textbook *reading book *teaching reference book *exercises book *studying plan Technology /Educational Technology /Modern Educational Technology /Educational Technology in Chinese Teaching /multi-media technology /net technology /cloud serving technology *white board *net meeting *chat room *blog Teaching Basic Theory of the Teaching teaching aim teaching task teaching objective teaching model teaching tactics teaching principle teaching program teaching reform teaching case Courseware teaching resources teaching experiment /mother tongue teaching A Term List of 1. 教材（ JC ） 教材编写 /语文教材 /编写教材 / 统编教材 /实验教材 /母语教材 /新课程教材 * 课本 * 读本 * 教学参考书（教参） * 练习册 *学案 2. 技术（ JS ） / 教育技术 /现代 教育技术 /语文 教育技术 /多媒 体技术 / 网络 技术 /云服务技 术 * 白板 *网 络会议 *聊天室 * 博克 3. 教学 （JX ） 教学基本理论 教学目的 教学 任务 教学目标 教学模式 教学 策略 教学原则 教学大纲 教学 改革 教学案例 教学课件 教学 资源 教学实验 /母语教学
手弧焊的工艺特点焊接工艺参数
手弧焊的工艺特点焊接工艺参数 一、手工电弧焊的工艺特点： 1、优点： (1)工艺灵活、适应性强：适用于碳钢、低合金钢、耐热钢、低温钢和不锈钢等各种材料的平、立、横、仰各种位置以及不同厚度，结构形状的焊接。 (2)质量好：与气焊、埋弧焊相比，金相组织细热影响区小，接头性能好。 (3)易于通过：工艺调整来控制变形和改善应力。 (4)设备简单、操作方便。 2、缺点： (1)对焊工要求高：焊工的操作技术和经验直接影响产品质量的好坏。 (2)劳动条件差：焊工在工作时必须手脑并用，精神高度集中，而且还要受到高温烘烤，有毒、烟、尘和金属蒸气的危害。 (3)生产率低：受焊工体质的影响，焊接工艺参数选择较小，故生产率低。 3、应用范围： 在造船、锅炉及压力容器、机械制造、建筑结构、化工设备等制造维修行业中都广泛使用手工电弧焊。 二、手工电弧焊的工艺参数： 选择合适的焊接工艺参数，对提高焊接质量和生产率是十分重要的。 焊接工艺参数(焊接规范)是指焊接时为保证焊接质量而选定的诸物理量。
1、焊条种类和牌号的选择：主要根据母材的性能，接头的刚性和工作条件选择焊条，焊接一般低碳钢和低合金钢主要是按等强原则选择焊条的强度级别，对一般结构选用酸性焊条，重要结构选用碱性焊条。 2、焊接电源种类和极性的选择：手弧焊时采用的电源有交流和直流两大类，根据焊条的性质进行选择，通常酸性焊条可同时采用交、直两种电源，一般优先采用交流弧焊机，碱性焊条，由于电弧稳定性差，所以必须采用直流弧焊机，对药皮中含有较多稳弧剂的焊条，亦可使用交流弧焊机，但此时电源的空载电压应较高些。 采用直流电源时，焊件与电源输出端正、负极的接法叫极性。 焊件接电源正极，焊条接电源负极的接线法叫正接，也称正极性，反之称为反接，也称反极性。 极性的选择原则： (1)碱性焊条常采用反接，因为碱性焊条正接时，电弧燃烧不稳定，飞溅严重，噪声大，使用反接时，电弧燃烧稳定，飞溅很小，而且声音较平静均匀，酸性焊条，如使用直流电源时通常采用正接。 (2)因为阴极部分的温度高于阳极部分，所以正接可以得到较大的熔深，因此，焊接厚钢板时可采用正接而焊接薄板、铸铁、有色金属时，应采用反接。 采用交流电源时，不存在正接和反接的接线法。 (3)焊条直径，可根据焊件厚度进行选择，厚度越大，选用的焊条直径应越粗，但厚板对接接头坡口打底焊时要选用较细焊条，另外接头形式不同，焊缝空间位置不同，焊条直径也有所不同，如T形接头应比对接接头使用的焊条粗些，立焊横焊等空间位置比平焊时所选用的应细一些，立焊最大直径不超过5mm，横焊、仰焊直径不超过4mm。 焊条直径与焊件厚度的关系(mm)
手工电弧焊特点与分类
手工电弧焊的特点 一、手工电弧焊的特点： 1.手工电弧焊与其他电弧焊方法相比，它具有如下特点: (1)电弧在焊条端部与工件之间燃烧，熔化的焊条要焊条部形成熔滴，在电弧力的作用下向熔池中过渡，与母材金属熔合在一起，冷凝后形成焊缝。 (2)焊条由焊芯和药皮组成。焊芯是拉制或铸造的实心金属棒，或装入金属粉末的金属管，在焊接时，既是电极又是填充金属。药皮是矿石粉末、铁合金粉、有机物和化工制品等原料按一定比例配置后压涂在焊芯表面的一层涂料。它能提高电弧的稳定性、减少飞溅、改善熔滴过渡和焊缝成形，还能通过熔渣和熔池中熔化的母材进行脱氧、去硫、去磷、去氢和渗合金等焊接反应，去除有害兀素，添加有益兀素，从Ifn获得合适的焊缝化学成分。 (3)在焊接时，它既不采取保护气体，也不采取焊剂保护熔化的焊条和熔池，Ifn是通过焊条药皮熔化或分解后主生气体和熔渣，隔绝空气，防止熔滴的熔池金属与空气接触，熔渣凝固后形成的渣壳覆盖在焊缝表面，防止高温的焊缝金属被氧化，提高焊缝质量。 (4)手工电弧焊机由弧焊电源装置和焊钳组成，设备简单适用，简便灵活，适应性强，但对焊工操作技术要求高。 二、手工电弧焊的分类: 1.根据所用焊接设备的不同，手工电弧焊可以分为: (1)交流电源的手工电弧焊: 流过电弧的电流为交流的手工电弧焊方
法。一般用在采用酸性焊条和低氢钾型焊条接普通焊接结构的场合。 (2)直流电源的手工电源弧焊: 流过电弧的电流为直流的手工电弧焊方法。一般用在采用碱性焊条焊接重要焊接结构的场合。 2.根据所用焊条种类的不同，手工电弧焊可分为: (1)厚药皮焊条的手工电弧焊: 药皮的质量系数K30%一50 %，目前生产中使用的基本上都是厚药皮的焊条。 (2)薄药皮焊条的手工电弧焊:药皮的质量系数I} = I%一2%。
工程专业术语中英文对照
工程专业术语中英文对照
CDB工程专业术语中英文对照(二） 添加时间：2013-4-24 节流截止放空阀 2011-08-10 16:50:46| 分类：English | 标签：|字号大中小订阅 六、仪表及自动控制 通用描述 COMMON DESCRIPTION 设备名称Equipment Name 缩写 ABB. 分散控制系统Distributed Control System DCS 安全仪表系统Safety Instrumentation System SIS 紧急切断系统Emergency Shutdown system ESD 火气系统Fire and Gas system F&G 监视控制和数据采集系统 Supervisory Control and Data Acquisition SCADA 可编程逻辑控制器Programmed Logic Controller PLC 远程终端单元Remote Terminal Unit RTU 站控系统Station Control System SCS 中央控制室Central Control Room CCR 操作间Operation room 机柜间Equipment room/ Cabinet room 大屏显示系统Large Screen Display system LSD 流量类仪表 FLOW INSTRUMENT 设备名称Equipment Name 孔板Orifice Plate 文丘里流量计Venturi Flowmeter 均速管流量计Averaging Pitot Tube 阀式孔板节流装置 Orifice Plate in quick change fitting 涡轮流量计Turbine Flowmeter
钢筋手工电弧焊工艺标准 (411-1996)
钢筋手工电弧焊工艺标准 (411-1996) 范围 本工艺标准适用于工业与民用建筑的钢筋及埋件手工电弧焊。 施工准备 2.1 材料及主要机具： 2.1.1 钢筋：钢筋的级别、直径必须符合设计要求，有出厂证明书及复试报告单。进口钢筋还应有化学复试单，其化学成分应满足焊接要求，并应有可焊性试验。预埋件的锚爪应用Ⅰ、Ⅱ级钢筋。钢筋应无老锈和油污。 2.1.2 钢材：预埋件的钢材不得有裂缝、锈蚀、斑痕、变形，其断面尺寸和机械性能应符合设计要求。 2.1.3 焊条：焊条的牌号应符合设计规定。如设计无规定时，应符合表4-14的要求，焊条质量应符合以下要求： 钢筋电弧焊使用的焊条牌号表4-14 项次钢筋级别搭接焊、帮条焊坡口焊 1 Ⅰ级 E4303 E4303 E4303 2 Ⅱ级 E430 3 E4303 E5003 3 Ⅲ级 E5003 E5003 E5503 4 Ⅰ、Ⅱ级与钢板焊接 E4303 注：不含25MnSi钢筋。 2.1. 3.1 药皮应无裂缝、气孔、凹凸不平等缺陷，并不得有肉眼看得出的偏心度。 2.1. 3.2 焊接过程中，电弧应燃烧稳定，药皮熔化均匀，无成块脱落现象。 2.1. 3.3 焊条必须根据焊条说明书的要求烘干后才能使用。 2.1. 3.4 焊条必须有出厂合格证。 2.1.4 弧焊机、焊接电缆、电焊钳、面罩、堑子、钢丝刷、锉刀、榔头、钢字码等。 2.2 作业条件： 2.2.1 焊工必须持有考试合格证。 2.2.2 帮条尺寸、坡口角度、钢筋端头间隙、接头位置以及钢筋轴线应符合规定。 2.2.3 电源应符合要求。 2.2.4 作业场地要有安全防护设施、防火和必要的通风措施，防止发生烧伤、触电、中毒及火灾等事故。
房务部专业术语中英文对照
房务部：Rooms Division 前厅部：Front Office 客房部：Housekeeping 大堂副理：Assistant Manager 宾客关系主任：Guest Relation Officer 前台：Front Desk 接待处：Reception/Check-in 收银处：Cashier/Check-out 领班：Captain 主管：Supervisor 班次负责人：Shift Leader 商务中心：Business Center 客房服务代表：Guest service agent(接待和收银合并之后的前台人员的称呼)简称GSA 电话总机：Switch Board 接线员：Operator 预订处：Room Reservation 礼宾服务处：Concierge 大厅服务处：Bell Service 金钥匙：Golden Key 行政楼层：Executive Floor 行政酒廊：Executive Lounge 行李生：Bellman 迎宾员：Doorman 夜审：End of Day /Night auditor 2．前厅服务项目专业术语介绍 入住：Check-in 退房：Check-out 外币兑换：Foreign Currency Exchange 问询：Information 接送机服务：Pick up service 叫醒服务：Wake up call 请勿打扰服务：DND Do not disturbed 失物招领：Lost and Found 国内直拨和国际直拨电话：DDD and IDD Domestic Direct Dial and International Direct Dial对方付费电话：Collect Call 3．前厅常用物品术语介绍： 住宿登记单：Registration card 欢迎卡：Welcome card 订房凭证：Voucher 交接本：log book 信封：Envelope 房卡钥匙：Room key 安全保管箱：Safe Deposit Box 客房统计和出售率统计的术语 预离房：Expected Departure 预抵房：Expected Arrival
电影专业术语中英文对照
documentary(film)记录片,文献片 filmdom电影界literaryfilm文艺片musicals音乐片comedy喜剧片 tragedy悲剧片draculamovie恐怖片sowordsmenfilm武侠片detectivefilm侦探片ethicalfilm伦理片affectionalfilm爱情片eroticfilm黄色片westernmovies西部片filmd’avant-garde前卫片 serial系列片 trailer预告片 cartoon(film)卡通片,动画片 footage影片长度 full-lengthfilm,featur efilm长片short(film)短片 colourfilm彩色片(美 作:colorfilm) silentfilm默片,无声片 dubbedfilm配音复制的影 片,译制片 silentcinema,silentfil ms无声电影 soundmotionpicture,tal kie有声电影 cinemascope,CinemaScop e西涅玛斯科普型立体声 宽银幕电影,变形镜头式 宽银幕电影 cinerama,Cinerama西涅 拉玛型立体声宽银幕电影, 全景电影 title片名 originalversion原着 dialogue对白 subtitles,subtitling字 幕 credits,credittitles对 原作者及其他有贡献者的 谢启和姓名 telefilm电视片 演员actors cast阵容 filmstar,moviestar电影 明星 star,lead主角 double,stand-in替身演 员 stuntman特技替身演员 extra,walker-on临时演 员 characteractor性格演员 regularplayer基本演员 extra特别客串 filmstar电影明星 filmactor男电影明星 filmactress女电影明星 support配角 util跑龙套 工作人员technicians adapter改编
常用焊接方法及特点
一、什么是钎焊？钎焊是如何分类的？钎焊的接头形式有何特点？ 钎焊是利用熔点比母材低的金属作为钎料，加热后，钎料熔化，焊件不熔化，利用液态钎料润湿母材，填充接头间隙并与母材相互扩散，将焊件牢固的连接在一起。 根据钎料熔点的不同，将钎焊分为软钎焊和硬钎焊。 （1）软钎焊：软钎焊的钎料熔点低于450°C，接头强度较低(小于70 MPa)。 （2）硬钎焊：硬钎焊的钎料熔点高于450°C，接头强度较高(大于200 MPa)。 钎焊接头的承载能力与接头连接面大小有关。因此，钎焊一般采用搭接接头和套件镶接，以弥补钎焊强度的不足。 二、电弧焊的分类有哪些，有什么优点？ 利用电弧作为热源的熔焊方法，称为电弧焊。可分为手工电弧焊、埋弧自动焊和气体保护焊等三种。手工自动焊的最大优点是设备简单，应用灵活、方便，适用面广，可焊接各种焊接位置和直缝、环缝及各种曲线焊缝。尤其适用于操作不变的场合和短小焊缝的焊接；埋弧自动焊具有生产率高、焊缝质量好、劳动条件好等特点；气体保护焊具有保护效果好、电弧稳定、热量集中等特点。 三、焊条电弧焊时，低碳钢焊接接头的组成、各区域金属的组织与性能有何特点？ （1）焊接接头由焊缝金属和热影响区组成。 1）焊缝金属：焊接加热时，焊缝处的温度在液相线以上，母材与填充金属形成共同熔池，冷凝后成为铸态组织。在冷却过程中，液态金属自熔合区向焊缝的中心方向结晶，形成柱状晶组织。由于焊条芯及药皮在焊接过程中具有合金化作用，焊缝金属的化学成分往往优于母材，只要焊条和焊接工艺参数选择合理，焊缝金属的强度一般不低于母材强度。 2）热影响区：在焊接过程中，焊缝两侧金属因焊接热作用而产生组织和性能变化的区域。 （2）低碳钢的热影响区分为熔合区、过热区、正火区和部分相变区。 1）熔合区位于焊缝与基本金属之间，部分金属焙化部分未熔，也称半熔化区。加热温度约为1 490～1 530°C，此区成分及组织极不均匀，强度下降，塑性很差，是产生裂纹及局部脆性破坏的发源地。 2）过热区紧靠着熔合区，加热温度约为1 100～1 490°C。由于温度大大超过Ac3，奥氏体晶粒急剧长大，形成过热组织，使塑性大大降低，冲击韧性值下降25%～75%左右。
电影专业术语中英对照
电影专业术语中英文对照 A Above-the-line 线上费用 A-B roll A-B卷 AC 交流电 Academy ratio 学院标准画框比 Adaptation 改编 ADR editor ADR 剪辑师 Aligator clamp=gaffer grip 固定灯具的弹簧夹，又称鳄鱼夹 Ambient Sounds 环境音 Amp 安培 Amplification 信号放大 Amplitude 振幅 Analog 模拟 Anamorphic lens 变形镜头 Aperture 光圈 Answer Print 校正拷贝 Arc 摄像机的弧度运动 Art director 艺术指导 Aspect ratio 画框比 Atmosphere sound 气氛音 Attack 起音 Audio board 调音台 Audio mixer 混音器，混音师 Automatic dialogue replacement 自动对白补录 Automatic focus 自动对焦 Automatic gain control 自动增益控制 Automatic iris 自动光圈(少用) Axis of action 表演轴线 B Back light 轮廓光 Background light=Scenery light 场景光 Balance 平衡 Balanced 平衡电缆 Barndoor 遮扉（灯具上的黑色金属活动板，遮光用的） Barney 隔音套 Base 片基（用来附着感光乳剂的胶片基底） Base plate 底座（固定灯的） Baselight level 基本亮度 Batch capturing 批次采集 Below-the-line 线下费用 Bidirectional 双向麦克风 Bit depth 位元深度（在数字声音中每次取样的数目，通常是8，12,16）
音乐专业术语中英文对照
Accordion 手风琴 Aftertouch 触后 Alto 女低音 Amplitude 振幅 Amplitude Modulation(AM) 调幅Analogue 模拟的 Anticipation 先现音 Arpeggio 琶音，分解和弦Attack 起音 Audio 音频 Augmented 增音程，增和弦Ballade 叙事曲 Band 波段，大乐队 Banjo 班卓琴（美国民间乐器）Bank 音色库 Baritone 男中音 Barline 小节线 Baroque 巴罗克 Bass 贝司 Bassoon 大管（巴松） Brass 铜管总称 Cassette 卡座 Cello 大提琴 Channel 音色通道 Choir 人声合唱 Chord 和弦 Chorus 合唱效果器 Clarinet 单簧管 Clef 谱号 Combination 组合音色Compressor 压缩效果器Concerto 协奏曲 Console 调音台 Contrabass 低音提琴 Ctrl 控制器 Cymbal 镲，钹 Decay 衰减 Delay 延迟效果器 Digital 数码的 Diminished 减音程，减和弦Distorted 失真效果器 Dolby NR 杜比降噪
Dominant 属音（和弦） Dot 附点 Drum 鼓 Duration 音符的时值 Echo 回声，反射 Effector 效果器 Encore 返场加演曲目 English Horn 英国管 Enhance 增益 Envelope 包络 EQ(Equalizer) 均衡器 Exciter 激励器 External 外置的，外部设备的Fade in 淡入 Fade out 淡出 Fantasia 幻想曲 Filter 滤波器 Flange 凸缘效果器 Flat 降号 Flute 长笛 French Horn 圆号（法国号）Frequency 频率 Frequency Modulation(FM) 调频Fret 吉它指板 Fretless Bass 无品贝司 Grace Note 装饰音 Grand Piano 三角钢琴 Graphic 图解式的 Guitar 吉它 Harmonica 口琴 Harmony 和声，和声学 Harp 竖琴 Harpsichord 古钢琴Instrument 乐器 Intermezzo 间奏曲 Internal 内置的，内部的Interval 音程 Inversion 转位 Key 调 Keyboard 键盘 Leading-note 导音 LFO 低频震荡器
网络游戏专业术语中英文对照版
网络游戏专业术语中英文对照版 中英对照的网络游戏术语 AC – Armor Class，盔甲等级、级别 Account –账号，与密码P assword相对 Add –一只玩家加入到组队中，如果请求别人组队，可说Add me pls. AOE– Area E ffect Damage，区域作用魔法，指的是一个可以伤害一个区域中的一群怪物的魔法，即所谓的群攻，现并非魔攻专用 AE– Area E ffect，区域作用伤害 AFK – A way from Keyboard，暂时离开(键盘)，意味着玩家暂时不再操控游戏角色，通知其他玩家注意 Aggro –指一些敌对、主动攻击的怪物，当角色接近它时，它会试图攻击角色，这种行为成为Aggro Aggro Radius –怪物周围的区域，进入它意味着怪物会“苏醒”并主动攻击你 Agi – Agility的缩写，意为敏捷，多指代游戏中角色的属性 Avatar –你的角色，互联网中常用来指头像，如论坛中的会员头像等 Beta –游戏的测试 Bind(Bound) –重生复活点 Boss –游戏中的终极怪物，通常各个级别段都有不同的Boss，中文里可以称为大王，老头儿等 Buff –主要指辅助类角色为别人施加的有益状态，通俗的说法就是“加状态”，典型的如增加防御、回血速度、躲避率等等 Bug –游戏中的漏洞 Carebear –喜欢帮助别人攻击怪物的玩家 Caster –不能抗怪的角色，如法师 CBT – Closed Beta Test 游戏封闭测试 CD – Cool Down, 多指技能的冷却时间 Character –游戏中的角色 Cheat –游戏中的作弊，也只游戏秘笈 Cheese –利用游戏的不平衡之处牟利 Combat P ets –被玩家控制的NP C，在战斗中帮助玩家及其队友，直译也有宠物的意思 CR – Corpse Retrevial的缩写，指取回尸体，这要看具体游戏的设置而论，很多游戏没有这个设置 Creep –怪物 Creep Jacking –当其他玩家与怪物战斗的时候趁机攻击该玩家 Critters –面对玩家攻击不会反击的怪物 DD – Direct Damage，直接伤害，非持续性伤害作用 DBUFF – De-Buff的简写，对怪物或敌对玩家施放的具有负面状态，如是对方减速、降低防御、降低准确率等等Defense –防御，这是通俗的叫法，具体还有物防、魔防等分类 DKP– Dragon Kill P oint的缩写，直译是屠龙点数，一种对玩家贡献的衡量标准 DMG – Damage的缩写，指伤害 DOT – Damage over time，在一段时间内持续对目标造成伤害，持续伤害 DP S – Damage per second的缩写，每秒伤害 Dungeon –指地宫、地下城等，多指游戏中难度很大的地形，也是Boss的栖居地 FH – Full Health的简写，指生命值全满 FM – Full Mana的简写，指法力全满 Forge –要塞，可以是游戏中的场景、地图 FS – Full Sport的缩写，指完全负责辅助的角色；汉语里可以做为法师的简称，注意区别
电焊技术基本手法图
手弧焊是用手工操作的焊接方法，因此焊缝的质量在很大程度上决定于焊工的操作技术。手弧焊时焊条要做三个方向的运动：朝熔池方向逐渐送进；沿焊接方向逐渐移动：必要时作有规则的横向摆动。 1）焊条朝熔池方向逐渐送进，这是为了以维持所要求的电弧长度。因此，焊条的送进速度应等于焊条的熔化速度，如果送进速度比熔化速度慢，则电弧被逐渐拉长，严重时形成断弧现象;反之，如果焊条送进速度太快，则弧长迅速缩短，最后导致焊条弓弩手焊件接触短路，电弧熄灭。 2）焊条沿焊接方向的移动速度，即手弧焊的焊接速度。太快时，电弧来不及熔化中够的焊条和母材，造成焊缝断面太小以及容易形成末焊透等缺陷；太慢时，熔化金属堆积过多，加大了焊缝断面，并且使焊件加热温度过高，薄件则容易烧穿。 3）焊条作横向摆动是为了获得一定宽度的焊缝，特别是当焊件开坡口时，由于焊口较宽，常采用摆动焊条使两侧金属能够焊透。 手弧焊常用的运条方法示意图： （1）直线形运条法焊接时焊条不作横向摆动，沿焊接方向作直线运动，
常用于开I形坡口的对接平焊、多层焊的第一层焊道或多层多道焊。 （2）直线往复运条法焊接时焊条末端沿焊缝的纵向作来凹直线形摆动，特点是焊接速度快、焊缝窄、散热快，适一薄板和接头间隙较大的多层焊的第一层焊道。 （3）锯齿形运条法焊接时焊条未端作锯齿形连续摆动及向前移动，并在两边稍停片刻，摆动焊条是为了控制熔化金属的流动和得到必要的焊缝宽度，特点是操作容易掌握，各种焊接位置基本上均可采用。 （4）月牙形运条法焊接时焊条末端沿着焊接方向作朋牙形的左、右摆动，特点是金属熔化良好，有较长的保温时间，气体容易析出，熔渣易上浮，焊缝质量较高。 （5）三角形运法焊接时焊条末端分别作连续的斜三角或正三角形运动，并向前移动。 斜三角形运条法适于焊接平、仰位置的T形接头焊缝和有坡口的横焊缝，特点是能够借焊条的摆动来控制熔化金属、焊缝成形良好。正三角形运条法只适于开坡口的对接接头和T 形接头焊缝的立焊，特点是一次就能焊出较厚的焊缝断面，焊缝不易产生夹渣，生产率较高。
电气专业术语中英文对照
电气专业术语中英文对 照 TYYGROUP system office room 【TYYUA16H-TYY-TYYYUA8Q8-
一．电气名词 Electric items 二．线路（母线、回路）Lines (Bus , circuits) 三．设备 Equipments 四．保护、继电器 Protection , relays 五．电气仪表 Electric instruments 六．防雷 Lightning protection 七．接地 Grounding , earthing 八．室、所 Room , Substation 九．电修车间设备 Equipments of electric repair 十．材料 Material 十一．图名 Drawings , diagrams 十二．表头 Tables 十三．标准图词汇 Terms from standard DWG 一．电气名词 Electric items 交（直）流 Alternating (direct) current
短路电流 Short-circuit current 起始次暂态短路电流 Initial subtransient short-circuit current 冲击电流 Impulse current 稳态短路电流 Steady state short-circuit current 临界电流 Critical current 切断电流 Rupturing current 熔断电流 Blow-out current 故障电流 Fault current 计算电流 Calculating current 极限有限电流 Limit effective current 过电流 Over current 逆电流 Inverse current 整定电流 Setting current 额定电流 Rated current 电流密度 Current density 短路电流最大有效值 Maximum effective value of short-circuit current 高压 High-voltage , High-tension 低压 Low-voltage , Low-tension 计算电压 Calculating voltage 激磁电压 Exciting voltage 冲击电压 Impulse voltage 临界电压 Critical voltage 残留电压 Residual voltage 击穿电压 Puncture voltage