阅读说明：本技术 一种具有良好组织稳定性的复相强化高锰合金及制备方法 (Complex phase reinforced high manganese alloy with good structure stability and preparation method thereof ) 是由 严靖博 谷月峰 袁勇 杨征 张醒兴 于 2021-08-27 设计创作，主要内容包括：本发明属于材料领域,具体涉及一种具有良好组织稳定性的复相强化高锰合金及制备方法,按质量百分比满足如下范围要求：C：0.06～0.09％,Cr：15～18％,Ni：2.5～3.5％,Mn：5～10％,Si：0.2～0.5％,B：0.003～0.007,Mo：0.5～1.5％,W：4～6％,Al：1.0～1.5％,余量为Fe。本发明的合金采用真空熔炼及热轧加工的方式制备成型,热处理完成后合金为铁素体基体,晶内弥散分布颗粒状NiAl相与杆状LAVES相,且其在650℃长时热暴露期间析出相长大速率较慢。合金具有良好的室温及高温力学性能。(The invention belongs to the field of materials, and particularly relates to a complex phase reinforced high manganese alloy with good structure stability and a preparation method thereof, wherein the complex phase reinforced high manganese alloy meets the following requirements in percentage by mass: c: 0.06-0.09%, Cr: 15-18%, Ni: 2.5-3.5%, Mn: 5-10%, Si: 0.2-0.5%, B: 0.003 to 0.007, Mo: 0.5-1.5%, W: 4-6%, Al: 1.0-1.5%, and the balance Fe. The alloy is prepared and formed by adopting a vacuum melting and hot rolling processing mode, the alloy is a ferrite matrix after the heat treatment is finished, granular NiAl phase and rod-shaped LAVES phase are dispersed and distributed in the crystal, and the growth rate of precipitated phase is slow in 650 ℃ long-time heat exposure period. The alloy has good mechanical properties at room temperature and high temperature.)

1. A complex phase strengthening high manganese alloy with good structure stability is characterized in that: comprises the following steps in mass fraction: c: 0.06-0.09%, Cr: 15-18%, Ni: 2.5-3.5%, Mn: 5-10%, Si: 0.2-0.5%, B: 0.003 to 0.007, Mo: 0.5-1.5%, W: 4-6%, Al: 1.0-1.5 percent, and the balance of Fe, wherein the alloy consists of a ferrite matrix and grain boundary carbides, and granular NiAl phases are dispersed and distributed in the grains.

2. The complex phase strengthened high manganese alloy with good structure stability as claimed in claim 1, wherein: in the alloy, both a granular NiAl phase and a rod-shaped LAVES phase are precipitated in the ferrite, and the volume percentage of the granular NiAl phase and the rod-shaped LAVES phase is not more than 10%.

3. The complex phase strengthened high manganese alloy with good structure stability as claimed in claim 1, wherein: the alloy has yield strength not lower than 420MPa at room temperature, yield strength not lower than 200MPa at 650 ℃, elongation not lower than 18% at room temperature and elongation not lower than 45% at 650 ℃.

4. A preparation method of a complex phase strengthening high manganese alloy with good structure stability is characterized in that according to the mass fraction, C: 0.06-0.09%, Cr: 15-18%, Ni: 2.5-3.5%, Mn: 5-10%, Si: 0.2-0.5%, B: 0.003 to 0.007, Mo: 0.5-1.5%, W: 4-6%, Al: 1.0-1.5% and the balance of Fe are smelted in vacuum, taken out of a furnace and poured to obtain an ingot;

homogenizing the cast ingot, then carrying out solid solution treatment after the cast ingot is processed and deformed in a hot rolling mode, and finally carrying out aging treatment, and carrying out water cooling or air cooling after the treatment is finished.

5. The method for preparing the complex phase strengthened high manganese alloy with good structure stability according to claim 4, wherein the vacuum degree of smelting is not higher than 0.5Pa, and the tapping and casting temperature is not lower than 1600 ℃.

6. The preparation method of the complex phase reinforced high manganese alloy with good structure stability as claimed in claim 4, wherein the homogenization treatment temperature is 950-1050 ℃ and the time is 8-24 h.

7. The method for preparing the complex phase strengthened high manganese alloy with good structure stability according to claim 4, wherein the deformation temperature is not lower than 750 ℃ and the single-pass deformation is not lower than 35%.

8. The method for preparing the complex phase strengthened high manganese alloy with good structure stability according to claim 4, wherein the temperature of the solution treatment is 1000-1100 ℃ and the time is 30-60 min.

9. The preparation method of the complex phase strengthened high manganese alloy with good structure stability as claimed in claim 4, wherein the temperature of aging treatment is 700-750 ℃ and the time is 8-12 h.

10. The method for preparing the complex phase strengthened high manganese alloy with good structure stability of claim 4, wherein the alloy is a ferrite matrix after solution treatment, and the volume percentage of retained austenite is not more than 10%.

Technical Field

The invention belongs to the field of alloy steel for high temperature, and particularly relates to a complex phase strengthening high manganese alloy with good structure stability and a preparation method thereof, which has high obdurability and good corrosion resistance at the temperature of more than 650 ℃, and can meet the use requirements of hot channel pressure-bearing parts such as a coal-fired unit filter/reheater, a main steam pipeline, a header and the like on long-term service under the high-temperature condition.

Background

The high-efficiency clean high-parameter ultra-supercritical coal-fired power generation technology is one of the main development trends of the clean coal-fired power generation technology in the world. At present, the thermal efficiency of a 700 ℃ advanced ultra supercritical (A-USC) coal-fired power generation system which is researched can exceed 50%, and the power supply coal consumption is lower than 240G/KW. The commercial value of the A-USC technology will depend on a number of variables: coal prices, nickel-based alloy costs (about 20 times the cost of high-grade ferritic steels), and carbon taxes, among others. The thermal efficiency of 650 ℃ and the secondary reheating unit thereof can exceed 50%, the power supply coal consumption is lower than 260G/KW, and the method is one of effective ways for realizing high-level industrial upgrading of the electric power industry in China and realizing clean coal power generation in a standardized way at present in a short time.

Compared with the traditional austenitic heat-resistant steel, the ferritic heat-resistant steel has the characteristics of low thermal expansion coefficient, good thermal conductivity, excellent stress corrosion resistance, low alloy cost (containing a small amount of or even no precious metals such as nickel) and the like, and is a preferred material for hot end parts of a unit, particularly thick wall parts such as pipelines, headers and the like. However, with the further improvement of steam parameters, the existing commercial ferritic heat-resistant steel is difficult to meet the performance requirements of hot end parts of the unit on alloy high-temperature strength, steam oxidation resistance and corrosion resistance (small pipes), and the recommended use temperature of the widely-used 9-12Cr and improved ferritic heat-resistant steel is generally not higher than 620 ℃. The strength performance of the alloy is effectively improved by adding Cu element into the G115 alloy, but the corrosion resistance and oxidation resistance of the alloy under the higher-temperature service working condition can not be effectively guaranteed because the content of Cr element is not more than 9%. Austenitic heat-resistant steel with higher heat-resistant strength, such as Super304H, HR3C and the like, has higher thermal expansion coefficient and poorer heat transfer efficiency, so that the austenitic heat-resistant steel is sensitive to temperature fluctuation, and further easily causes the problems of thermal fatigue damage and the like, thereby causing the peak shaving operation capability of a boiler to be reduced. Therefore, the thick wall parts in the current USC unit still use ferrite heat-resistant steel such as P92 as the preferred material.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a complex phase reinforced high manganese alloy with good structure stability and a preparation method thereof.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a complex phase strengthened high manganese alloy with good structure stability comprises the following components in percentage by mass: c: 0.06-0.09%, Cr: 15-18%, Ni: 2.5-3.5%, Mn: 5-10%, Si: 0.2-0.5%, B: 0.003 to 0.007, Mo: 0.5-1.5%, W: 4-6%, Al: 1.0-1.5 percent, and the balance of Fe, wherein the alloy consists of a ferrite matrix and grain boundary carbides, and granular NiAl phases are dispersed and distributed in the grains.

The further improvement of the invention is that the granular NiAl phase and the rod-shaped LAVES phase in the alloy are both precipitated in the ferrite, and the volume percentage of the granular NiAl phase and the rod-shaped LAVES phase are not more than 10 percent.

The further improvement of the invention is that the alloy has yield strength not lower than 420MPa at room temperature, yield strength not lower than 200MPa at 650 ℃, elongation not lower than 18% at room temperature and elongation not lower than 45% at 650 ℃.

A preparation method of a complex phase strengthening high manganese alloy with good structure stability comprises the following steps of according to the mass fraction: 0.06-0.09%, Cr: 15-18%, Ni: 2.5-3.5%, Mn: 5-10%, Si: 0.2-0.5%, B: 0.003 to 0.007, Mo: 0.5-1.5%, W: 4-6%, Al: 1.0-1.5% and the balance of Fe are smelted in vacuum, taken out of a furnace and poured to obtain an ingot;

homogenizing the cast ingot, then carrying out solid solution treatment after the cast ingot is processed and deformed in a hot rolling mode, and finally carrying out aging treatment, and carrying out water cooling or air cooling after the treatment is finished.

The further improvement of the invention is that the vacuum degree of smelting is not higher than 0.5Pa, and the temperature of tapping and pouring is not lower than 1600 ℃.

The further improvement of the invention is that the temperature of the homogenization treatment is 950-1050 ℃, and the time is 8-24 h.

The invention is further improved in that the deformation temperature is not lower than 750 ℃, and the single-pass deformation is not lower than 35%.

The invention has the further improvement that the temperature of the solution treatment is 1000-1100 ℃ and the time is 30-60 min.

The method is further improved in that the temperature of the aging treatment is 700-750 ℃, and the time is 8-12 h.

The invention is further improved in that the alloy after solution treatment is a ferritic matrix, and the volume percentage of retained austenite does not exceed 10%.

Compared with the prior art, the invention has the beneficial effects that: ferrite has low strength at high temperature, and although carbide can improve the high-temperature strength of the ferrite, the chromium carbide is rapidly coarsened along with the increase of the content of Cr in a corrosion-resistant element, so that the strengthening effect of the chromium carbide is lost. The NiAl phase can effectively improve the high-temperature strength of the alloy, but the ductile-brittle transition temperature of the alloy is easily increased due to excessive addition of the Al content, and the addition of the Ni element also causes the increase of the cost of alloy raw materials. Therefore, the invention adopts a NiAl phase and LAVES phase composite strengthening pair mode to control the size and the growth rate of a precipitated phase, and finally obtains good high-temperature service performance; the Mn element is beneficial to reducing the alloy stacking fault energy, promoting the formation of deformation twin crystals and further inhibiting the crack initiation. Meanwhile, the addition of Mn element is beneficial to improving the work hardening tendency, improving the strength performance of the alloy and finally ensuring that the alloy obtains excellent obdurability. In the ferrite heat-resistant steel, along with the increase of the content of W, Al, Mo, Ti and other alloying elements, the ferrite heat-resistant steel is beneficial to obviously improving the strength performance at room temperature and high temperature, but can also cause the ductile-brittle transition temperature to rise and seriously harm the room temperature plasticity, so the invention adopts a multiphase strengthening mode, coordinates and considers the high-temperature strengthening effect of the alloy and the influence on the ductile-brittle transition temperature, controls the content of the forming elements of a single strengthening phase, inhibits the rapid growth of the single strengthening phase at high temperature to obtain good high-temperature stability of the structure, and simultaneously avoids the phenomenon of greatly improving the ductile-brittle transition caused by overhigh alloying degree. The alloy is suitable for high-temperature service working conditions of 650-700 ℃, such as a super-supercritical coal-fired unit reheater, a main steam pipeline, a header and the like.

According to the invention, solid solution and aging treatment are adopted, rapid growth of a NiAl phase in an aging process is avoided, the aging time is controlled to ensure sufficient precipitation of an LAVES phase in a crystal grain, and finally a two-phase composite strengthened alloy matrix structure is obtained, so that good mechanical properties of the alloy are ensured.

Furthermore, the alloy has the characteristics of a two-phase strengthening structure of the LAVES and the NiAl, and the nucleation and growth kinetics of the two strengthening phases are obviously different, so that the heat treatment parameters need to be reasonably controlled in the aging process to ensure that the two strengthening phases reach ideal sizes and volume fractions.

Drawings

FIG. 1 is the microstructure morphology of the alloy of example 1 in the heat treated state.

FIG. 2 shows the microstructure of the alloy of example 1 in a thermal exposure state at 650 ℃/500 h.

Detailed Description

The present invention will be described in further detail with reference to examples.

The complex phase strengthening high manganese alloy with good structure stability comprises the following elements in percentage by mass: c: 0.06-0.09%, Cr: 15-18%, Ni: 2.5-3.5%, Mn: 5-10%, Si: 0.2-0.5%, B: 0.003 to 0.007, Mo: 0.5-1.5%, W: 4-6%, Al: 1.0-1.5%, and the balance Fe. The alloy after heat treatment consists of ferrite matrix and grain boundary carbide, and granular NiAl phase is dispersed and distributed in the grain.

Smelting the elements in vacuum according to the mass percentage, controlling the vacuum degree to be not higher than 0.5Pa, and controlling the tapping and casting temperature of the alloy to be not lower than 1600 ℃ to obtain the ingot.

Homogenizing the cast ingot at the temperature not higher than 1050 ℃ for 8-24 h.

And then, hot rolling is adopted for processing deformation, the deformation temperature is not lower than 750 ℃, and the single-pass deformation is not lower than 35%.

And secondly, carrying out solid solution treatment, wherein the solid solution treatment is carried out at the temperature of 1000-1100 ℃, the heat preservation time is 30-60 min, and water cooling is carried out after the treatment is finished.

And finally, carrying out aging treatment, wherein the temperature of the aging treatment is within the range of 700-750 ℃, the heat preservation time is 8-12 h, and water cooling or air cooling is carried out after the treatment is finished.

The alloy is a ferrite matrix after solution treatment, and the volume fraction of the retained austenite is not more than 10%;

after aging treatment, the granular NiAl phase and the rod-shaped LAVES phase are both precipitated in the ferrite grains, and the volume fraction of the NiAl phase and the rod-shaped LAVES phase is not more than 10%.

The precipitated phase in the alloy has good high-temperature stability, and the structure change is not obvious after the alloy is exposed for 500 hours at 650 ℃.

The alloy has good mechanical properties at room temperature and high temperature, the yield strength of the alloy is not lower than 420MPa and 200MPa at room temperature and 650 ℃, and the elongation is not lower than 18% and 45%, respectively.

Example 1

The high-strength corrosion-resistant alloy material comprises the following components in percentage by mass: c: 0.08%, Cr: 15%, Ni: 3.0%, Mn: 10%, Si: 0.4%, B: 0.005, Mo: 1.0%, W: 5.0%, Al: 1.0 percent and the balance of Fe.

The preparation method of this example includes the following steps:

1) preparing raw materials: the components by mass percentage are as follows: c: 0.08%, Cr: 15%, Ni: 3.0%, Mn: 10%, Si: 0.4%, B: 0.005%, Mo: 1.0%, W: 5.0%, Al: 1.0 percent and the balance of Fe.

2) Smelting and forming: the alloy is smelted in vacuum, and the tapping and casting temperature of the alloy is controlled to be 1600 ℃. After the completion, the ingot is homogenized for 24h at 1000 ℃. The alloy is processed and deformed in a hot rolling mode, wherein the rolling temperature is 1000 ℃, the finish rolling temperature is 750 ℃, and the single-pass deformation is 35%.

3) And (3) heat treatment: the alloy is subjected to solution treatment at 1100 ℃, the heat preservation time is 30min, and water cooling is carried out after the treatment is finished. The aging treatment temperature is 750 ℃, the heat preservation time is 12h, and water cooling is carried out after the treatment is finished.

Example 2

The preparation method of this example includes the following steps:

1) preparing raw materials: the components by mass percentage are as follows: c: 0.06%, Cr: 18%, Ni: 3.5%, Mn: 8%, Si: 0.2%, B: 0.007%, Mo: 0.8%, W: 4.0%, Al: 1.5 percent and the balance of Fe.

2) Smelting and forming: the alloy is smelted in vacuum, the vacuum degree is not higher than 0.5Pa, and the tapping and casting temperature of the alloy is controlled to 1650 ℃. After the completion, the ingot is homogenized at 1050 ℃ for 8 h. The alloy is processed and deformed in a hot rolling mode, the rolling temperature is 1000 ℃, the finish rolling temperature is 750 ℃, and the single-pass deformation is 35%.

3) And (3) heat treatment: the alloy is subjected to solution treatment at 1000 ℃, the heat preservation time is 60min, and water cooling is carried out after the treatment is finished. The aging treatment temperature is 740 ℃, the heat preservation time is 9h, and water cooling is carried out after the treatment is finished.

Example 3

The preparation method of this example includes the following steps:

1) preparing raw materials: the components by mass percentage are as follows: c: 0.07%, Cr: 17%, Ni: 2.5%, Mn: 6%, Si: 0.3%, B: 0.004%, Mo: 0.5%, W: 6.0%, Al: 1.4 percent and the balance of Fe.

2) Smelting and forming: the alloy is smelted in vacuum, the vacuum degree is not higher than 0.5Pa, and the tapping and pouring temperature of the alloy is controlled to be 1630 ℃. After the completion, the ingot was homogenized at 950 ℃ for 24 hours. The alloy is processed and deformed in a hot rolling mode, the rolling temperature is 1000 ℃, the finish rolling temperature is 750 ℃, and the single-pass deformation is 35%.

3) And (3) heat treatment: the alloy is subjected to solution treatment at 1030 ℃ for 50min, and is cooled by water after the treatment is finished. The aging treatment temperature is 720 ℃, the heat preservation time is 10h, and water cooling is carried out after the treatment is finished.

Example 4

The preparation method of this example includes the following steps:

1) preparing raw materials: the components by mass percentage are as follows: c: 0.09%, Cr: 16%, Ni: 2.8%, Mn: 5%, Si: 0.5%, B: 0.003%, Mo: 1.5%, W: 4.5%, Al: 1.2 percent and the balance of Fe.

2) Smelting and forming: the alloy is smelted in vacuum, the vacuum degree is not higher than 0.5Pa, and the tapping and casting temperature of the alloy is controlled to be 1620 ℃. After the completion, the ingot is homogenized for 24h at 1000 ℃. The alloy is processed and deformed in a hot rolling mode, the rolling temperature is 1000 ℃, the finish rolling temperature is 750 ℃, and the single-pass deformation is 35%.

3) And (3) heat treatment: the alloy solution treatment is carried out at 1070 ℃, the heat preservation time is 40min, and water cooling is carried out after the treatment is finished. The aging treatment temperature is 700 ℃, the heat preservation time is 12h, and water cooling is carried out after the treatment is finished.

Comparative example 1

The high-strength corrosion-resistant alloy material comprises the following components in percentage by mass: c: 0.08%, Cr: 15%, Ni: 3.0%, Mn: 10%, Si: 0.4%, B: 0.005, Mo: 1.0%, W: 5.0%, Al: 2.0 percent and the balance of Fe.

The preparation method of this example includes the following steps:

1) preparing raw materials: the components by mass percentage are as follows: c: 0.08%, Cr: 15%, Ni: 3.0%, Mn: 10%, Si: 0.4%, B: 0.005%, Mo: 1.0%, W: 5.0%, Al: 2.0 percent and the balance of Fe.

2) Smelting and forming: the alloy is smelted in vacuum, and the tapping and casting temperature of the alloy is controlled to be 1600 ℃. After the completion, the ingot is homogenized for 24h at 1000 ℃. The alloy is processed and deformed in a hot rolling mode, wherein the rolling temperature is 1000 ℃, the finish rolling temperature is 750 ℃, and the single-pass deformation is 35%.

3) And (3) heat treatment: the alloy is subjected to solution treatment at 1000 ℃, the heat preservation time is 30min, and water cooling is carried out after the treatment is finished. The aging treatment temperature is 750 ℃, the heat preservation time is 12h, and water cooling is carried out after the treatment is finished.

Comparative example 2

The high-strength corrosion-resistant alloy material comprises the following components in percentage by mass: c: 0.08%, Cr: 15%, Ni: 2.0%, Mn: 5.0%, Si: 0.4%, B: 0.005%, Mo: 1.0%, W: 5.0%, Al: 1.0 percent and the balance of Fe.

The preparation method of this example includes the following steps:

1) preparing raw materials: the components by mass percentage are as follows: c: 0.08%, Cr: 15%, Ni: 2.0%, Mn: 5.0%, Si: 0.4%, B: 0.005, Mo: 1.0%, W: 5.0%, Al: 1.0 percent and the balance of Fe.

2) Smelting and forming: the alloy is smelted in vacuum, and the tapping and casting temperature of the alloy is controlled to be 1600 ℃. After the completion, the ingot is homogenized for 24h at 1000 ℃. The alloy is processed and deformed in a hot rolling mode, wherein the rolling temperature is 1000 ℃, the finish rolling temperature is 750 ℃, and the single-pass deformation is 35%.

3) And (3) heat treatment: the alloy is subjected to solution treatment at 1100 ℃, the heat preservation time is 30min, and water cooling is carried out after the treatment is finished. The aging treatment temperature is 750 ℃, the heat preservation time is 12h, and water cooling is carried out after the treatment is finished.

Comparative example 3

The high-strength corrosion-resistant alloy material comprises the following components in percentage by mass: c: 0.08%, Cr: 18%, Ni: 8.0%, Mn: 10.0%, Si: 0.4%, B: 0.005%, Ti: 1.4%, W: 4.0%, Al: 1.2 percent and the balance of Fe.

The preparation method of this example includes the following steps:

1) preparing raw materials: the components by mass percentage are as follows: c: 0.08%, Cr: 18%, Ni: 8.0%, Mn: 10.0%, Si: 0.4%, B: 0.005, Ti: 1.4%, W: 4.0%, Al: 1.2 percent and the balance of Fe.

2) Smelting and forming: the alloy is smelted in vacuum, and the tapping and casting temperature of the alloy is controlled to be 1600 ℃. After the completion, the ingot is homogenized for 24h at 1000 ℃. The alloy is processed and deformed in a hot rolling mode, wherein the rolling temperature is 1000 ℃, the finish rolling temperature is 750 ℃, and the single-pass deformation is 35%.

3) And (3) heat treatment: the alloy is subjected to solution treatment at 1100 ℃, the heat preservation time is 30min, and water cooling is carried out after the treatment is finished. The aging treatment temperature is 750 ℃, the heat preservation time is 12h, and water cooling is carried out after the treatment is finished.

The alloy is composed of a ferrite matrix and precipitated phases which are distributed in a fine and dispersed mode in the crystal after heat treatment, and the figure 1 shows. After the alloy is subjected to heat exposure for 650 ℃/500h, the structure appearance of the alloy does not change obviously (figure 2), and the alloy has good structure stability.

The mechanical properties of the alloy are tested, and the result shows that the alloy of example 1 has good room temperature and high temperature strong plasticity, and the elongation at room temperature can reach 21.3 (table 1). When the aluminum content in the alloy is increased to 2% (comparative examples 1 and 2), the brittleness is obviously increased, and the increase of the Al is shown to increase the ductile-brittle transition temperature of the alloy. When the Ni content in the alloy was further increased, the room-temperature plasticity of the alloy could be improved (comparative example 3), but the cost of the alloy increased significantly, and the presence of a large number of austenite grains also resulted in a large increase in the coefficient of thermal expansion (table 2).

TABLE 1 tensile Properties of the alloys at room temperature and 650 deg.C

TABLE 2 average coefficient of thermal expansion of the alloy/10^-6*K^-1

The invention firstly improves the Cr element content in the alloy to more than 17 percent so as to ensure that the alloy has good corrosion resistance and oxidation resistance at the temperature of more than 650 ℃; meanwhile, by promoting the nucleation of NiAl phase and LAVES phase which are dispersed and distributed in the crystal, a good precipitation strengthening effect is obtained, and the high-temperature strength performance of the alloy is improved; in addition, a proper amount of Mn element for reducing the fault energy of the alloy layer is added, so that the strain-induced twinning phenomenon is promoted, the toughness of the alloy at room temperature is improved, and the work hardening capacity of the alloy is improved. Finally, the novel ferrite heat-resistant steel with good high-temperature strength performance and corrosion/oxidation resistance is obtained.

The alloy is prepared and formed by adopting a vacuum melting and hot rolling processing mode, the alloy is a ferrite matrix after the heat treatment is finished, granular NiAl phase and rod-shaped LAVES phase are dispersed and distributed in the crystal, and the growth rate of precipitated phase is slow in 650 ℃ long-time heat exposure period. The alloy has good mechanical properties at room temperature and high temperature, the yield strength of the alloy is not lower than 420MPa and 200MPa at room temperature and 650 ℃, and the elongation is not lower than 18% and 45%, respectively.