TW477820B - The thermomechanical treatment for low temperature superplasticity in 5083 Al-Mg base alloys - Google Patents

Abstract

The invention is concerned with the thermomechanical treatment for low temperature superplasticity in 5083 Al-Mg base alloys. By this process, the plates of Al-Mg alloys with a thickness of 20 to 50 mm were first hold at a high temperature of 500 to 540 DEG C for 1 to 9 hours and cooled, then hot-rolled to 1 to 3 mm with reduction ratio of 85 to 98%. During hot-rolling, the plates must have been kept at single direction of rolling and returned to the heating furnace several times at various intermediate thickness. After performing the above thermomechanical treatment, the tensile tests for evaluating superplasticity were conducted on the as-fabricated sheets at a low temperature of 230 to 350 DEG C, which is lower than those for recrystallization, grain growth, and even loss in magnesium (> 500 DEG C). Moreover, the range used of deformation temperature is not low enough to induce high stress and thus cavities. As a consequence, the Al-Mg base sheets produced by this process have the high commercial merit because their superplasticity could reach up to 200% and more at the relatively low temperature of 250 DEG C under a strain rate of above 1 x 10<SP>-3</SP> S<SP>-1</SP>. In addition, the process of the thermomechanical treatment has been simplified to fewer steps as well, as compared to those described in the literatures.

Description

4 // 52U Amendment No. 871182M V. Description of the invention (1) The present invention relates to a thermomechanical treatment method for inserting a low, w-thin α WH k ^ y diameter, and plasticity, especially referring to a low temperature Superplastic 5 0 8 3 button to catch people ^ &amp; a ^ Thermal mechanical processing method of magnesium alloy. Know: 'Some metal materials under the condition of Tongzhuangzhuang, w become mouths, mouth A, under the conditions of Hiyama · ^ y field, generally refers to the superplastic Pompano at high temperature and low speed. ^ 5, top Phenomenon, such as · broken glass or polymer materials, can be stretched up to thousands of hundreds of centimeters before breaking, &amp; specialists u 丨, 卞 100 knife than this superplastic molding (SPF) industry Can be used as the best method for direct forming at high temperature; &amp;, general super, the behavior occurs when some materials have the largest deformation rate response constant (m value) or fine grains, superplastic deformation mainly slides to each other by grain boundaries (Ie grain hundary sliding (GBS) for the organization 'with other compensation (accomniociation), followed by 7 j · * heart, y silly people can use this atomic diffusion transmission, or may be a special event of the poor row' due to A large number of grain boundaries are required between the grains to generate shape, so the smaller the daily grains (the larger the total surface area of the grain boundaries), the easier the superplasticity will occur. Furthermore, if one wants to achieve considerable superplasticity, it is either to use the characteristics of the two-phase interface in eutectic or eutectoid alloys, or to strengthen the grain boundary slip between grains. The latter can only be used in materials with fine grains. Effectively, therefore, for non-two-phase eutectic (eutectoid) alloys, such as aluminum alloys, micronization of grains has become an important issue; according to the current two approaches for the successful development of aluminum alloy superplastic materials, one is It is to increase the amount of certain elements to generate high-temperature precipitates and to suppress the grain growth during annealing. For example, in the A 丨 (Al) _Cu (Copper) system

Supral 150 plus 5% by weight (weight ratio) &amp; (A1-6wt% Cu-0.50 / 〇

Zr) ^ Another way is to apply a suitable thermomechanical treatment (TMTS), such as in 7XXX series Al-Zn-Mg or Ai-Li alloys. Because whether it is Al-Cu, A1-Zn-Mg, or Al-Li alloys, they are all developed with a focus on aviation materials. Based on the consideration of energy saving and exhaust gas pollution, the weight of steam engines has become an important issue. , And · Aluminum alloy in steam

477820 _ Case No. 87118253 A_M Revision V. Description of the invention (2) The usage ratio in the car will gradually increase. The above-mentioned aerospace aluminum alloys are very expensive, and it is impossible to apply them to automobiles and motorcycles in large quantities. The more feasible alloy systems are A1-Mg, A1-Mg-Si, and Al-Si. In the solution-strengthened A 1 -Mg series alloys, there have been some reports of efforts to make fine-grained materials with superplasticity, which can be roughly divided into two categories. One is the development of high temperature superplasticity (Η TSP). The grain size is about 7 ~ 10 μm, the optimal superplasticity temperature is 500 ~ 5 50 ° C, the optimal superplasticity rate is about 10 ~ 4 si, and the superplastic stretch is about 40. Above and below 0%, this is a relatively mature research and development achievement; the other is an attempt to develop low temperature superplasticity (LTSP), whose grains are usually claws, and the superplasticity temperature is expected to drop to 3 0 0 t: or lower, superplasticity The rate is expected to be higher than 1 Xl0'4s_1; In addition, international reports have not seen examples of very successful low temperature superplasticity for commercial 503 alloys, such as Kawaz〇e et al. • Developed a 506 system using equal-diameter angular extrusion Shape (eqUalchannel anguUr ⑽, ECA) to make grains 0.3 "claw material, but at low temperature superplastic society r ^ 200 Π, it will be reduced to 90% &lt; stretch *, the higher the speed of the amount of Ai -Mg experimental binary alloy material, at ^ ... and: 2 2 Π 0% tensile amount, when the rate is two, X 1 0-2s-1 when the tensile amount decreases If it is 130% 80%, 30% degrees, the grains will be quickly reshaped… such as & and the stretching temperature „Shaanxi fans grow up, because in this solid solution strengthened alloy, μ ts 1 day and day grains grow Talef f et al · For the phase said—Al-2. 8Mg i Yezujing's g ', 5. 5M§ system, gas measurement between 20 0 ~ 350 ℃. ^ The amount is roughly in the range of 50 ~ 2 0 0% coffee lambda, stretched within AU / 〇, ni eh eta 1 · Attempt to fight against the A 1-Mg-Sc contract of the sleeve, w M against Russia-using rolling method to make grains 1 V M's thin handle, Wf! M &quot; '— Page 7 477820 Case No. 87118253 V. Description of the invention (3) However, at 3 50 ° C and 1 XI O-Y1, only 80% of the stretch amount, in other cases It is also not ideal. Taleff et al. Also tried to add Mn or Zr to Ai-Mg. At 400 C, the tensile amount was only 150-190%, and lower than 400 Dc. Another type of thinking in developing low-temperature superplastic A 1 -Mg alloys is to use experimentally high Mg alloys, such as Al-7Mg and Al-1 lMg alloys of Woo et al ·, at 300 ° C and 1 X 10_2s- At 1 hour, it is 12%; the most successful example is McNelley et al.'S Al-10Mg-0.1Zr alloy with grain size of 丨, which has an extremely high tensile strength of 00% at 300 ° C and 1 X 10 ° C. The elongation amount also maintains a tensile amount of 400% at 30 () t and 5 X 1 0 2 s_1, but this material is an experimental alloy. As for commercial use, no progress has been made yet. 'Furthermore, there are two new directions in the development of superplastic materials today, one is high strain rate superpiasticity (like "), and the other is low temperature superplasticity (LTSP), the former superplastic sheet material, generally Both need to be at a high temperature of about 500 ~ 5 50 ° C, in order to have good superplasticity. Because of the superplastic forming at 500. (: the above is bound to avoid serious grain growth, such as In the plastic thin plate, the grain size is 5, and after high temperature superplastic forming, the grain size becomes more than 1 5 // m, and even the grain boundary slip that cannot be performed due to excessive grain growth loses superplasticity; in addition, In the state of forming at high temperature, 'the loss of alloying elements will occur in the aluminum alloy' causes the surface of the thin sheet to have a layer of loss zone (s0 丨 ute de-plet ion zone) after forming. The solute is lost and the resistance is reduced, so the grains in this local area are greatly increased, and the superplasticity is lost, so many cracks are generated, which has a great impact on the mechanical properties after forming. It is often necessary to pickle or grind away after forming. 0 // m surface ′ To restore its proper mechanical properties; for this reason, the manufacturing method of conventional superplastic magnesium alloys has not yet been perfected.

Page 8 477820 Amendment No. 871182K! V. Description of the invention (4) Yourong Yusi, the inventor of this case has carefully considered and has been engaged in alloys: research and development experience for many years, and has ample knowledge i: : Qiao 'After several trials and trials, the main purpose of the invention # 22 二 f invention was finally devoted to providing a general-purpose, low-temperature, superplastic 5083-free magnesium-based alloy for thermal processing. Method. According to the above purpose, the low temperature superplastic 5083 aluminum-magnesium thermomechanical treatment method of the present invention, Douyi Yougu, w also + m H to l, has the same temperature heat treatment step in order, and will be after hot rolling Following this, the aluminum-magnesium sheet was kept at 9 =% in the temperature range of 500 ~ 54 °, and then cooled; and the thermal mechanical processing step, the completion rate of the foregoing steps was only rolled to a thickness of 3mm, and rolled and cut. The bucket L and the temple are between 85 ~ 98%, and during the rolling process, the aluminum-magnesium sheet is different: the thickness is daily, and it must be returned to the furnace several times, and the rolling operator needs to maintain a single direction to reach the aluminum-magnesium sheet. At 25 ~ 25 0 t: at low temperature, it has the characteristics of low-temperature superplastic drawing, thereby reducing the manufacturing cost, so as to achieve the purpose of 'almost cheap' for the widespread use of aluminum and magnesium sheet.

The reason is that the low-temperature superplastic 5083 aluminum-magnesium alloy thermomechanical treatment method of the present invention has a high-temperature heat treatment step in sequence. It will be 2 ~ 50 mm 2 magnesium sheet after hot rolling at 500 ~ 540 ° C temperature range for 9 hours, and then cooled in air; and heat machine processing step, rolling the non-money plate after the completion of the foregoing steps in the temperature range of 25 ~ 25 0 ° C to a thickness of 3mm, rolling The reduction rate is maintained between 85 ~ 98%, and during the rolling process, the aluminum-magnesium sheet must be reheated several times at different intermediate thicknesses, and its reheating temperature is 100 ~ 250 ° C ... The direction of the original hot rolling of the magnesium sheet is horizontal or vertical rolling. 'With the implementation of the above steps, omitting the prior knowledge before rolling must be preceded by the chamber 477820 _ Case No. 87118253 V. Description of the invention (5) _ Temperature = application 3 The stretching amount of% ~ 10%, as well as eliminating the two steps of long heat before rolling ... The present invention not only has the simple effect, but also has the obtained p, mechanical processing steps, and its super-shape. J which has reached 200% or more of the industrial application value = to understand the purpose, efficacy, and structure of the present invention, and to cite-a feasible embodiment and the description of the diagram = ... The description of the exposed thermo-mechanical treatment method π = is based on the 5083 sheet (30_thickness) produced by Sinosteel Mingye Company, as shown in the figure, Taiji &amp; M = monthly car only Schematic diagram, = all examples of bismuth have sequentially high temperature heat treatment steps, and Miya, θ or = machine = step 2; first 'high temperature heat treatment = 30mm aluminum and magnesium sheet at 500. After ~ 5 ^ hours, cool in the air, and then maintain η0 ″ between 1 ° and 9 ° C: Step 2 'The room temperature or intermediate temperature frosting step 2 to temperature; 2 = time; and W 向 在The whole process; when maintaining the furnace several times, the Lüzhen board must return to the two people's wares and dishes when the intermediate thickness is different. ⑽ Hold it for 3 ~ 3 ° minutes before continuing to roll down. Bell alloy special ":: 之: 程) trolling s applied at room temperature page〗 〖0

X 477820 Amendment No. 87118253 V. Description of the invention (6) Aging heat treatment is performed for a long time before rolling, and (3) Cold processing at normal temperature can also be used. Basically, the purpose of simplifying the heat engine processing steps has been achieved. Continuing the eye, the second picture shown in Figure 2 is a comparison diagram of the true stress-strain curve of the original dry plate and the aluminum-magnesium plate after heat treatment in a preferred embodiment of the present invention. As shown in the figure, the aluminum-magnesium plate of the original thick plate As shown by the dashed line in the figure, there is a work hardening phenomenon, and the aluminum-magnesium sheet after heat treatment shows a process softening phenomenon. It can be seen that after proper heat treatment, the aluminum-magnesium sheet 2 does have a material that can reach superplasticity. As shown in the three figures, the stress exhibited by the heat-treated aluminum-magnesium sheet after a preferred superplastic heat treatment according to a preferred embodiment of the present invention should be as follows: The stress indicated by the dashed line will decrease rapidly, and its maximum stress generally occurs near the strain = 0! If the low temperature superplasticity is better, the stress first shows a temporary work hardening, but then it decreases, and its maximum stress-generally occurs at strain = G In the vicinity of 4, according to the past experience of this laboratory, the aluminum-magnesium treated by the heat engine gradually turns into a 冋 angle boundary, and then the grain boundary slip can be carried out, and necking begins before the fruit can be turned into a high-angle grain boundary ( necking), two Hair should be born in 'cross-ten specimen strain occurred in the ratio of 4: 1 were 0.5, preferably may be in the Xu superplasticity. Comparison of the low-temperature superplasticity of some 5 083 Shaoxing original thick plates with aluminum alloys and aluminum alloys processed by this, this, and this machine: 477820

Case No. 87118253 Rev. V. Description of the invention (7) State temperature (° 〇 Rate (s ~ l) UTS (MPa) Elongation (° / 〇) Original thick plate 200 8 χ 1 〇-4 220 63 250 8 X 1 〇-4 133 84 350 8χι-4-4 95 113 300 8χι-4 ~~~ 60 150 Heat of the present invention 200 8χι-4-4 140 119 After machine treatment 230 8χι-4 94 300 Aluminum-magnesium sheet 250 8χι- 4 64 350 270 8 × ι〇-4 60 260 300 8 × ι〇-4 50 200 350 8 × ι〇-4 42 203 According to the purpose of the preliminary test, when performing the thermal mechanical treatment (TMTS) of the present invention &quot;in; * Keep the it rate between 85,% during the process; and the rolling direction is in the whole direction. In addition, during the rolling process, the aluminum-magnesium sheet: or it must be returned to the furnace several times perpendicular to the original hot rolling to bring its temperature back to What you want to attack; when the middle thickness is different, 丨 丨 丨 丨 --after the next rolling, only

Hold for 3 ~ 30 minutes before continuing to tumble dry; and the temperature range of 477820 477820

V. Description of the invention (8) Table 1 lists some typical test results of the original thick plate and the aluminum-magnesium plate processed by the heat engine of the present invention at 20 ~ 3 50 ° C. It can be clearly seen that the low-temperature superplasticity of the original thick plate is very poor, and the tensile amount is only 84% at 250 ° C, and the tensile strength at elevated temperature is also increased, which is a general coarse-grained solute drag creep ($ 〇 〇 1 ^ te dragcreep), the optimal superplastic temperature must be 500t: above,, the deformation rate response constant (value 15 ~ 0.2 left in the second 3 = the best heat-treated aluminum-magnesium sheet, stretched at 250 t The amount rises to 350%, H4. At 230 C and 270 C, the tensile amount is also 300% and has low-temperature superplasticity, and the superplastic deformation exceeds the commercial value °. In addition, the low temperature of 2 3 GC is also It conforms to 2 0 ～ 3 5 0. (: between the mesh Γ ruler change rate reaction constant is about 0.25 ~ 0.5, indicating that there is already an internal = two Ϊ ”structure operation: In addition, noteworthy I, from Table-It can be seen that the aluminum and magnesium sheet processed by the heat engine has a higher tensile strength (UTS) than thick. At 25 (rc and ⑴㈣, the tensile strength is reduced from the original: to the The “MPa” of the heat-treated plate of Shao lock plate will be greatly reduced when the mechanism is operated by the mechanism of slippage. The ratio of bite and capacity is dlslocation glide controlled. Mechanical processing "Second, f one, is 5083 1 Lu magnesium alloy After the thermal comparison of the present invention: Low temperature superplastic properties of the plate at different speeds of 25G Shaw

Page 13 477820 _Case No. 87118253_Year Month Day Amendment V. Description of the invention (9) State temperature rate UTS Elongation (X :) (s-1) (MPa) (° / 〇) Heat of the invention 250 5X10- 4 57 300 After processing 250 8X10- -4 64 350 In Luzhen sheet 250 1X10- -3 68 400 250 2X10- 3 89 300 250 5X10- 3 120 195 250 8X10- -3 130 175 Table 2 is shown in Table 2, At 250 ℃, the optimal superplastic deformation rate is 8 X 1 0_4s_1, 3 50¾ ί stretch amount J, but at 5 X 1 〇-3 S-1 still retain about 20% of the stretch The amount is much higher than the previously set superplastic deformation rate target of 1 X 1 O ^ s'1, so it basically has a superplastic deformation rate at a low temperature of 250 ℃, and can also get a superplastic deformation commercial 200% of stretch value. Please refer to the list in Table 2. It is 5 0 8 3 aluminum-magnesium alloy after two different thermomechanical treatments (room temperature rolling, medium temperature rolling), and different rolling amounts in 2 5 (ΓC and 8 X 1 Comparison of low-temperature superplastic properties at Ο-Υ1, as shown in 5

Rolling will be slightly better than room temperature rolling, but the difference is limited, so room temperature rolling is still quite competitive. An increase in rolling amount will help increase the low temperature superplasticity. The final stage of rolling is the most critical .

Page 14 477820 _ Case No. 87118253_ Year Month Day _ Amendment V. Description of the invention (10) State temperature rate UTS Elongation () (s-1) (MPa) (° / 〇) TMT, room temperature 250 8 X 1 0 ~ 4 110 188 Roll to 2mm TMT, room temperature 250 8x10-4 110 240 Roll to 1 mm TMT, medium temperature 250 8 X 1 0-4 80 225 Roll L to 2mm TMT, medium temperature 250 8 X 10 4 64 350 Rolled to 1 mm in Table 3 In addition, in order to have a better understanding of the implementation method of the present invention, the following specific experimental data are given to illustrate the characteristics of the present invention; please refer to the table 4 for 50. Comparison of the low-temperature superplastic properties of 8 3 aluminum-magnesium alloys after thermomechanical treatment at different rolling temperatures at 2 50 ° C and 1 X liPs-1: Among them, this experiment is based on 5 083 aluminum-magnesium sheets with a thickness of 30 bands. After the high temperature heat treatment step, the aluminum-magnesium sheet is kept at 500 ° C for 1 hour and then cooled; then heat is applied.

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V 477820

Machine processing steps, and according to the following different rolling temperatures, to maintain the rolling operation in a single direction, and timely return to the furnace, so that the rolling reduction rate reached 95%, the results obtained:

Rolling temperature rolling reduction rate UTS Elongation (C) — one to one (%)-. — (MPa) (° / 〇) 25 95% 108 205 100 95% 112 220 150 95% 98 266 200 95% 70 327 250 Two — — — — · 95% —————. — One 69 349 Table 4 T temperature rolling comparison: Among which '本 ^^ also refers to 30

As shown in Record 4, negative is better, and the rolling temperature is higher, so according to this experiment, it is known that the most suitable, and the rolling at 25 ° C is more economical, so the rolling temperature and 100 ~ 25 (TC medium temperature zone. In addition, as shown in Table 5, the 5 0 8 3 aluminum-magnesium alloy at 25 (rc and 丨 χΐ〇 will have a lower elongation than the low-temperature superplasticity of room temperature rolling ( Elongation) When the rolling temperature is larger, it is inferior to 100 ～ 2 50, but the properties are also acceptable. It is industrially defined in the low temperature region of 25 ～ 100 ° C, which is ^ s-1 after different reduction rates. The low-temperature superplastic material with a specific thickness of 5 0 8 3 in Shaozhen was firstly subjected to high 477820 case number 87118253 V. Description of the invention (12) Correct the heat treatment step to keep it at a temperature of 5 0 ° c Cool down after 1 hour; then implement the heat engine treatment step, and maintain the rolling operation in a single direction according to the rolling temperature of 2000, and return to the furnace in time to achieve the following different rolling reduction rates. The results obtained are as follows: Delay reduction rate (t) (%) 200 91% 200 93% 200 95% 200 98% UTS (MPa) ~--Elongation (%) 89 18 6 80 2 24 70 327 66 344-As shown in Table 5, the rolling reduction rate becomes larger as shown in Table 5. The X ringing is louder, and the tensile strength (UTS) proves that the aforementioned increase in rolling amount is the most appropriate. The rolling reduction rate is the last. Please refer to Table 6 during the heat engine treatment process. The low temperature super straight (丄) with the original heat of 10 4s ^ or parallel to the ^ ^ elongation rate (E 1 ongat i is smaller), so according to this The experiment can further contribute to the characteristics of low-temperature superplastic properties between 85 ~ 98%. The column is the rolling direction of the 5083 aluminum-magnesium alloy in the rolling of this hair, compared with 8 at 25 0t. As shown, the rolling direction is the rolling direction. It also has a certain degree of influence ^ ^ The rolling direction will be when-through flat_ line, and stretch

477820 ^ ____ 87118253__Year Month Day ^ ^ _ V. Description of the invention (13) The highest tensile deformation rate is 350%, and when the rolling direction is perpendicular to the original hot rolling direction, the deformation amount is 250%. … State -----____---- Temperature (t :) Rate (s'1) UTS (MPa) Elongation (° / 〇) Best heat engine treatment (丄) — ~ 一一 — 一 —t __ 一· One-to-two 250 to one-one-to-one 8 X 1 0-4 75 250 Optimal heat engine treatment 250 8xl0-4 64 350 (//) Table 6 In summary, the low-temperature superplastic 5 083 aluminum-magnesium alloy of the present invention The thermo-mechanical treatment method can indeed be made into a superplastic aluminum-magnesium sheet through proper thermo-mechanical treatment. The elongation rate rises to 3 50% at 2 50 ° C and 8 X 10-4, and at 2 3 0 ° C and 8 1 At 0 4s 1 and 3 50 C and 8 X 1 〇-4s-i, the elongation is also 300% and

At 2 0 3 / 'and at a low temperature of 2 500 C, the superplastic deformation rate is 5 X 1 〇-4 si ~ 5 X 10, "", still maintains an elongation of about 2000%, which is much higher than the predetermined Objective] χ1〇s1 'Additionally' In view of the fact that generally only 200% of the deformation is required when superplastic forming is performed; it is known that the present invention can perform a sufficient ultra-high temperature at its low temperature of 2 3 0 t ~ 3 5 0 Plastic forming has the value of industrial utilization; and has never been

477820 _Case No. 87118253_Year Month Date__ V. Description of the invention (14) The essential elements of the patent shall be filed in accordance with the provisions of the Patent Law. However, the above is only a preferred embodiment of the present invention. Therefore, any equivalent structural change applied to the specification and patent application scope of the present invention should be included in the patent scope of the present invention. Brief description of the drawings: The first diagram is a schematic flowchart of a preferred embodiment of the present invention. The second figure shows a comparison of the true stress-strain curves of the original thick plate and the aluminum-magnesium plate after heat treatment in a preferred embodiment of the present invention.

The third figure shows a comparison diagram of the true true stress-strain curves of the aluminum-magnesium sheet after a poor and better heat engine treatment in a preferred embodiment of the present invention.

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X 477820 _Case No. 87118253_ Year Month Day Amendment

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Claims (1)

477 &amp; 2a 87118253 Amendment .............. Attachment to a low-temperature superplastic 5 083 aluminum-magnesium alloy thermo-mechanical treatment method, which includes the following steps: ,, high-temperature heat treatment step, hot-rolled 20 ~ A 50mm aluminum-magnesium sheet is held for 9 hours in a temperature range of 500 to 540 ° C, and then cooled; and a thermomechanical processing step, the aluminum-magnesium sheet obtained through the foregoing steps is rolled to a thickness of 1 to 1_3mni and rolled. The reduction rate is maintained between 85 ~ 98%, and t must be maintained in a single direction. At the same time, when the rolling operation is performed, it can be performed in the rolling temperature zone 2 and 100 ~ 25 (TC intermediate temperature zone). According to the scope of the patent application, the low-temperature heat treatment method of the alloy 逑 temperature superplasticity 508 "Luzhen cooling method is a heat treatment step in the air, which is based on the application patent || Wai g Q alloy Thermomechanical treatment method, 1 = The low-temperature superplastic 5083 aluminum-magnesium content is 5 ~ 20% each time ;;; ,,, middle, the heat treatment process is rolled back several times during the rolling process and: J For medium temperature rolling, it can be between and then maintained at the return temperature Between 100 ~ 25〇t rolling only need to be A in the air, and then continue rolling, the last rolling is based on the room temperature of the patent application. 5083 aluminum-magnesium alloy heat engine 3: the low-temperature superplastic step The rolling direction is flat --- ', ,,, and the heat engine process step 4 477820 case number 87118253 amendment Page 22