CN104630434A - Method for achieving superplasticity of 304 stainless steel by virtue of cyclic martensite phase transformation - Google Patents
Method for achieving superplasticity of 304 stainless steel by virtue of cyclic martensite phase transformation Download PDFInfo
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- CN104630434A CN104630434A CN201510042246.XA CN201510042246A CN104630434A CN 104630434 A CN104630434 A CN 104630434A CN 201510042246 A CN201510042246 A CN 201510042246A CN 104630434 A CN104630434 A CN 104630434A
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Abstract
The invention discloses a method for achieving superplasticity of 304 stainless steel by virtue of cyclic martensite phase transformation. According to the method, the problems of large difficulty, low production efficiency and high cost in industrial production are solved. The method comprises the following steps: (a) stretching a 304 stainless steel plate at uniform speed at the room temperature, wherein the stretching velocity v is more than 0 and less than or equal to 5mm/min, and the tensile deformation is 30%; (b) carrying out aging treatment on the stretched 304 stainless steel plate at a temperature T, wherein T is more than or equal to 700 DEG C and less than or equal to 900 DEG C, and aging treatment time t is more than or equal to 15min and less than or equal to 25min; and (c) repeatedly carrying out the steps (a) and (b), recording the number N of total cycles, snapping the 304 stainless steel plate which is cyclically processed for N times (N is equal to 1, 2, 3......), and counting total elongation rate deltatotal, so as to achieve phase change superplasticity when deltatotal is more than or equal to 100%.
Description
Technical field
The present invention relates to superplastic forming field, specifically be one be mainly used in steel realize the superplastic one of steel utilize martensitic transformation circulate realize the superplastic method of 304 stainless steel.
Background technology
Existing superplastic forming field is adopt fine crystalline superplastic material substantially, and have following deficiency: the thinning preprocess of crystal grain, grain-size general requirement is less than 5 μm; Certain texturing temperature, is generally 0.5T
m~ T
m, wherein T
malloy melting point, relevant with material composition, can handbook be looked into; Low strain rate, general requirement strain rate controls 10
-4~ 10
-1s
-1in scope.Therefore, the principal feature of fine crystalline superplastic is to equipment requirements high (high temperature deformation), poor efficiency and high pre-treatment expense, and this is also cause fine crystalline superplastic to be difficult to the reason of widespread use in superplastic forming field.
Mainly also be in the experimental study stage for the application of transformation superplasticity in plastic working field, the method of what reason was that now existing research mainly adopts is stress and high-temperature phase-change circulation synchronous, therefore equipment requirements is high, then cannot implement for large product at all.
Number of patent application is CN201010299718.7, utilizes the method that transformation superplasticity corrects shape metallic substance mechanical component; Be arranged in tooling by as-quenched condition by school shape part, tooling applies durability to by school shape part, is fixed in the qualified scope of tolerance of dimension by being surpassed tolerance parts by the geomery of school shape part; Together put into together with tooling the tempering heat treatment operation that tempering stove carries out normal process process by by school shape part, undergone phase transition in tempering heat treatment process by school shape part, utilize the superplasticity had during metal phase change, under the effect of durability, be there is the viscous deformation needed for the shape of school by school shape part; After tempering heat treatment operation completes, lay down tooling, obtain the part that tolerance of dimension is qualified.Shortcomings: need special tooling device, cost is high; Tooling device need put into tempering stove together with workpiece, and precision, the surface quality of tooling device will decline, and maintenance cost is high; By the restriction of tooling device for large-scale or need gross distortion workpiece to be difficult to carry out.
Number of patent application is CN201310234229.7, and pre-prepd wrought alloy blank initial grain degree is less than 10 μm, and becomes nearly equiax crystal state; Carry out under isothermal condition forging (temperature is 1040-1120 DEG C); Strain rate is 0.0001-0.0005s
-1.Shortcomings: need carry out pre-treatment to material grains size, increases cost; Isothermal forging is carried out wayward at high temperature; Strain rate is low, and production efficiency is low.
Summary of the invention
In order to overcome above-mentioned existing technological deficiency, the object of the invention is: provide that a kind of processing difficulty is low, cost is low and production efficiency is high utilizes martensitic transformation to circulate to realize the superplastic method of 304 stainless steel.
In order to achieve the above object, the present invention is achieved through the following technical solutions: utilize martensitic transformation to circulate and realize the superplastic method of 304 stainless steel, it is characterized in that comprising the following steps:
A, at room temperature at the uniform velocity to stretch to 304 stainless steel plates, bring out the austenite generation martensitic transformation in 304 stainless steels, wherein rate of extension v meets 0 < v≤5mm/min, and tensile deformation amount is 30%;
B, ageing treatment, namely under temperature T, be incubated 304 stainless steel plates after stretching, bring out the martensite reverse transformation in 304 stainless steels, supervene recovery stress simultaneously, wherein T meets 700 DEG C≤T≤900 DEG C, the time of insulation, namely aging time t meets 15min≤t≤25min;
C, recirculation step a, b, record global cycle times N;
D, by circulation N (N=1,2,3 ...) secondary after 304 stainless steel plates break, calculate percentage of total elongation δ
always, δ
alwayswhen>=100%, then realize transformation superplasticity.
Be that microcomputer controlled electronic universal tester CMT5105, rate of extension v meet 2.5mm/min≤v≤3.5mm/min to 304 stainless steel plates the adopted equipment that at room temperature at the uniform velocity stretches in step a.
Adopt chamber type electric resistance furnace to carry out ageing treatment to 304 stainless steel plates after stretching in step b, temperature T meets 750 DEG C≤T≤850 DEG C.
In step a, rate of extension v meets v=3mm/min.
In step b, described temperature T meets T=800 DEG C.
Described time t meets t=20min.
The invention has the beneficial effects as follows: of the present invention utilize martensitic transformation circulate realize the superplastic method of 304 stainless steel, by utilizing room temperature tensile stress can bring out 304 stainless steel martensitic transformations, and recovery stress in ag(e)ing process, during martensite reverse transformation, can be supervened; Martensitic transformation can carry out in room temperature, highly beneficial for practical application, and only needs Direct Air-Cooled to room temperature namely to complete once phase-change circulation after ageing treatment, carries out complicated heating and refrigeration cycle without the need to special equipment; Technique is simple and saved a large amount of production costs.
Embodiment
The present invention is further illustrated below, but protection scope of the present invention is not limited to the following stated.
Of the present invention utilize martensitic transformation circulate realize the superplastic method of 304 stainless steel, comprise the following steps:
A, at room temperature at the uniform velocity to stretch to 304 stainless steel plates, bring out the austenite generation martensitic transformation in 304 stainless steels, wherein rate of extension v meets 0 < v≤5mm/min, and tensile deformation amount is 30%; If speed is less, efficiency is lower, if speed is comparatively large, then because the crystal defects increase of material causes work hardening and crystal dislocation motion is more difficult, can causes occurring non-homogeneous viscous deformation too early, necking phenomenon is produced in advance, for superplastic realize unfavorable;
B, ageing treatment, namely under temperature T, be incubated 304 stainless steel plates after stretching, bring out the martensite reverse transformation in 304 stainless steels, supervene recovery stress simultaneously, wherein T meets 700 DEG C≤T≤900 DEG C, the time of insulation, namely aging time t meets 15min≤t≤25min; If temperature is lower than 500 DEG C, because temperature is lower, martensite reverse transformation ability reduces, and martensite reverse transformation is incomplete, and the accumulation effect for plasticity is poor; Temperature, between 500 DEG C ~ 700 DEG C, can cause the austenite intercrystalline precipitation Cr that reverse transformation obtains
23c
6, make to become Cr depletion zone near crystal boundary, produce serious intergranular corrosion; Temperature is too high, can produce the problems such as high temperature oxidation more than 900 DEG C;
C, recirculation step a, b, record global cycle times N;
D, by circulation N (N=1,2,3 ...) secondary after 304 stainless steel plates break, calculate percentage of total elongation δ
always, δ
alwayswhen>=100%, then realize transformation superplasticity.
Of the present invention utilize martensitic transformation circulate realize the superplastic method of 304 stainless steel, by utilizing room temperature tensile stress can bring out 304 stainless steel martensitic transformations, and recovery stress in ag(e)ing process, during martensite reverse transformation, can be supervened; Martensitic transformation can carry out in room temperature, highly beneficial for practical application, and only needs Direct Air-Cooled to room temperature namely to complete once phase-change circulation after ageing treatment, carries out complicated heating and refrigeration cycle without the need to special equipment; Technique is simple and saved a large amount of production costs.
It should be noted that described room temperature just illustrates the superiority of present method implementation process, namely implementation process is without the need to particular surroundings requirement, and as heating, cooling, constant temperature etc., room temperature environment a wider range that the method is implemented, all can carry out 0 DEG C ~ 40 DEG C room temperatures.
As preferably, be that microcomputer controlled electronic universal tester CMT5105, rate of extension v meet 2.5mm/min≤v≤3.5mm/min to 304 stainless steel plates the adopted equipment that at room temperature at the uniform velocity stretches in step a.Common drawing machine can certainly be selected to replace CMT5105.If speed is less, efficiency is lower, if speed is comparatively large, then because the crystal defects increase of material causes work hardening and crystal dislocation motion is more difficult, can causes occurring non-homogeneous viscous deformation too early, necking phenomenon is produced in advance, for superplastic realize unfavorable.
As preferably, adopt chamber type electric resistance furnace to carry out ageing treatment to 304 stainless steel plates after stretching in step b, temperature T meets 750 DEG C≤T≤850 DEG C.
As preferably, in step a, rate of extension v meets v=3mm/min.
As preferably, in step b, described temperature T meets T=800 DEG C.
As preferably, described time t meets t=20min, is to carry out completely in order to ensure martensite reverse transformation.Guaranteeing that martensite reverse transformation carries out completely in situation, the time is more short better.Energy-conservation on the one hand; Prevent because overlong time causes Austenite Grain Growth on the other hand, thus cause plasticity to decline.This time increases with specimen size and increases.
Some experimental datas are provided below.
Illustrate: 1, experimentally, namely cycle index all gets 2 times can realize superplasticity, compares its highest breaking elongation and finds its Optimal Temperature.
2, preferably aging temp is 800 DEG C.Although superplasticity is the highest when temperature is 900 DEG C, high by 5% time only than 800 DEG C, and temperature is high means that power consumption is high, oxidation is serious a lot.
Illustrate: aging time t is too short, martensite reverse transformation does not carry out completely, unfavorable to superplastic raising, and aging time t is oversize, causes the Austenite Grain Growth that reverse transformation generates, and also can reduce plasticity, and preferred aging time is 20min.
Illustrate: 1, rate of extension is lower, effect is better, but production efficiency can reduce greatly, thus draw speed be less than 3mm/min do not do specific experiment;
2, from result, when draw speed gets 3mm/min, superplasticity is best, but in practice, as long as can reach user's requirement, suitably can adopt any draw speed high.Such as, its total deformation of certain part requirements is 138%, and rate of extension can be adopted to be 7mm/min.
3, specific experiment result shows the later stage, when adopting draw speed to be 20mm/min, when deflection reaches 30%, sample does not break, but owing to being that the plastic deformation heat produced in martensitic process has little time to scatter and disappear at austenitic transformation, temperature is caused obviously to raise, inhibit martensitic generation to a certain extent, superplastic reduction will be caused.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any amendments done within the spirit and principles in the present invention, equivalent replacement and improvement etc., all should be included within protection scope of the present invention.
Claims (6)
1. utilize martensitic transformation to circulate and realize the superplastic method of 304 stainless steel, it is characterized in that comprising the following steps:
A, at room temperature at the uniform velocity to stretch to 304 stainless steel plates, bring out the austenite generation martensitic transformation in 304 stainless steels, wherein rate of extension v meets 0 < v≤5mm/min, and tensile deformation amount is 30%;
B, ageing treatment, namely under temperature T, be incubated 304 stainless steel plates after stretching, bring out the martensite reverse transformation in 304 stainless steels, supervene recovery stress simultaneously, wherein T meets 700 DEG C≤T≤900 DEG C, the time of insulation, namely aging time t meets 15min≤t≤25min;
C, recirculation step a, b, record global cycle times N;
D, by circulation N (N=1,2,3 ...) secondary after 304 stainless steel plates break, calculate percentage of total elongation δ
always, δ
alwayswhen>=100%, then realize transformation superplasticity.
2. according to claim 1 utilize martensitic transformation circulate realize the superplastic method of 304 stainless steel, it is characterized in that: be that microcomputer controlled electronic universal tester CMT5105, rate of extension v meet 2.5mm/min≤v≤3.5mm/min to 304 stainless steel plates the adopted equipment that at room temperature at the uniform velocity stretches in step a.
3. according to claim 1 utilize martensitic transformation circulate realize the superplastic method of 304 stainless steel, it is characterized in that: adopt in step b chamber type electric resistance furnace to stretch after 304 stainless steel plates carry out ageing treatment, temperature T meets 750 DEG C≤T≤850 DEG C.
4. the martensitic transformation circulation that utilizes according to Claims 2 or 3 realizes the superplastic method of 304 stainless steel, and it is characterized in that: in step a, rate of extension v meets v=3mm/min.
5. according to claim 4 utilize martensitic transformation circulate realize the superplastic method of 304 stainless steel, it is characterized in that: in step b, described temperature T meets T=800 DEG C.
6. according to claim 5 utilize martensitic transformation circulate realize the superplastic method of 304 stainless steel, it is characterized in that: the time t of described insulation meets t=20min.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106893813A (en) * | 2017-02-28 | 2017-06-27 | 浙江工贸职业技术学院 | Degenerated based on deformation twin and realize the superplastic method of TWIP steel |
| CN109777933A (en) * | 2019-02-26 | 2019-05-21 | 东南大学 | A kind of method that Light deformation strengthens martensitic stain less steel |
| CN113528778A (en) * | 2021-06-30 | 2021-10-22 | 中国科学院金属研究所 | Preparation method of superplastic high-silicon austenitic stainless steel |
| CN114606430A (en) * | 2022-03-01 | 2022-06-10 | 兴机电器有限公司 | Low-carbon Fe-Mn-Al-Si TWIP steel and preparation method thereof |
Citations (4)
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| JPH10265842A (en) * | 1997-03-27 | 1998-10-06 | Agency Of Ind Science & Technol | Production of super plastic stainless steel |
| JPH11199925A (en) * | 1998-01-14 | 1999-07-27 | Agency Of Ind Science & Technol | Method for superplastic working of stainless steel and manufacture of stainless steel for superplastic working |
| CN101392318A (en) * | 2008-06-18 | 2009-03-25 | 哈尔滨汽轮机厂有限责任公司 | Method for spring sizing by using metal transition superplasticity |
| CN101935744A (en) * | 2010-10-08 | 2011-01-05 | 哈尔滨汽轮机厂有限责任公司 | Method for sizing metal material mechanical part by phase change superplasticity |
-
2015
- 2015-01-28 CN CN201510042246.XA patent/CN104630434B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10265842A (en) * | 1997-03-27 | 1998-10-06 | Agency Of Ind Science & Technol | Production of super plastic stainless steel |
| JPH11199925A (en) * | 1998-01-14 | 1999-07-27 | Agency Of Ind Science & Technol | Method for superplastic working of stainless steel and manufacture of stainless steel for superplastic working |
| CN101392318A (en) * | 2008-06-18 | 2009-03-25 | 哈尔滨汽轮机厂有限责任公司 | Method for spring sizing by using metal transition superplasticity |
| CN101935744A (en) * | 2010-10-08 | 2011-01-05 | 哈尔滨汽轮机厂有限责任公司 | Method for sizing metal material mechanical part by phase change superplasticity |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106893813A (en) * | 2017-02-28 | 2017-06-27 | 浙江工贸职业技术学院 | Degenerated based on deformation twin and realize the superplastic method of TWIP steel |
| CN109777933A (en) * | 2019-02-26 | 2019-05-21 | 东南大学 | A kind of method that Light deformation strengthens martensitic stain less steel |
| CN109777933B (en) * | 2019-02-26 | 2020-08-11 | 东南大学 | Method for strengthening martensitic stainless steel through micro-deformation |
| CN113528778A (en) * | 2021-06-30 | 2021-10-22 | 中国科学院金属研究所 | Preparation method of superplastic high-silicon austenitic stainless steel |
| CN114606430A (en) * | 2022-03-01 | 2022-06-10 | 兴机电器有限公司 | Low-carbon Fe-Mn-Al-Si TWIP steel and preparation method thereof |
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