A kind of high corrosion resistance and high ductility stainless steel and preparation method thereof

Abstract

The present invention belongs to the field of stainless steel technology, and specifically relates to a highly corrosion-resistant and highly ductile stainless steel and a preparation method thereof. The highly corrosion-resistant and highly ductile stainless steel comprises the following chemical components by mass percentage: C 0.03-0.09%, Si 0.2-0.7%, Mn 7-9%, S 0.001-0.02%, P 0.03-0.05%, Ni 2-4%, Cr 16-17%, Cu 0.5-1.5%, N 0.15-0.2%, rare earth 0.05-0.2%, Mo 0.5-2.0%, Ti 0.1-0.5%, with the balance being Fe. The stainless steel of the present invention has high corrosion resistance and excellent mechanical properties, and can be used to prepare stainless steel inner containers with a high pass rate.

Description

Technical Field

[0001] The present invention belongs to the technical field of stainless steel, and in particular relates to a high-corrosion-resistant and high-ductility stainless steel and a preparation method thereof. Background Art

[0002] The inner liner of a stainless steel thermos is usually made of high-quality stainless steel, most commonly 304 or 316 stainless steel. These materials have good corrosion resistance, oxidation resistance, and good strength, which can effectively ensure the safety and taste of the beverage, while also helping to extend the service life of the thermos. 304 stainless steel is a common food-grade stainless steel material with good processing properties and corrosion resistance, suitable for most daily use scenarios. Compared to 304 stainless steel, 316 stainless steel has the addition of molybdenum, which makes it more corrosion-resistant, especially against pitting and crevice corrosion caused by chlorides, but its cost is higher.

[0003] CrMnN stainless steel is a new type of stainless steel developed to reduce costs. It partially replaces the nickel (Ni) in traditional 304 stainless steel by increasing the ratio of manganese (Mn) and nitrogen (N). This material offers unique advantages in the application of thermos flask liners. By reducing the use of expensive nickel, CrMnN stainless steel is relatively low-cost, which helps reduce production costs and potentially makes the product more competitive. The appropriate manganese and nitrogen content improves the strength and hardness of the stainless steel while maintaining good ductility and toughness. However, its corrosion resistance is not as good as that of stainless steels with high nickel content (such as 304 or 316), and it is particularly susceptible to pitting corrosion in chloride ion environments. CrMnN stainless steel also presents additional challenges in processing processes such as welding and forming. It is prone to cracking during hydroforming. Currently, the failure rate of stainless steel thermos flask liners made with it is as high as over 30%.

[0004] Therefore, there is an urgent need for a high corrosion-resistant and high ductility stainless steel and a preparation method thereof. Summary of the Invention

[0005] The object of the present invention is to provide a high corrosion-resistant and high ductility stainless steel and a preparation method thereof.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A high-corrosion-resistant and high-ductility stainless steel comprises the following chemical components in mass percentage: C 0.03-0.09%, Si 0.2-0.7%, Mn 7-9%, S 0.001-0.02%, P 0.03-0.05%, Ni 2-4%, Cr 16-17%, Cu 0.5-1.5%, N 0.15-0.2%, rare earth 0.05-0.2%, Mo 0.5-2.0%, Ti 0.1-0.5%, and the balance is Fe.

[0008] Preferably, the rare earth includes at least one of Y, La and Er.

[0009] Preferably, the rare earths include Y, La and Er in a mass ratio of 1: (1.3-1.5): (0.4-0.6).

[0010] Preferably, the mass percentage of Mo is less than the sum of the mass percentages of Cu and rare earth.

[0011] The present invention can improve the tensile strength of stainless steel by adding rare earths in a specific ratio. Analysis shows that the three rare earths work together to form composite inclusions with smaller sizes, reduce stress concentration, and further refine grains. On this basis, when the mass percentage of Mo is less than the sum of the mass percentages of Cu and rare earths, the corrosion resistance of stainless steel can be improved. Mo can improve the resistance of stainless steel to pitting and crevice corrosion in Cl⁻-containing environments by forming a stable Mo-containing passivation film, but excessive Mo will increase costs and induce σ phase precipitation, reducing toughness. The synergistic effect of Cu and rare earths can make up for the shortcomings of Mo, especially in complex corrosive environments, and the comprehensive corrosion resistance of stainless steel is better.

[0012] Preferably, the sum of C+N mass percent is ≥0.25%.

[0013] When the combined mass percentage of C+N in the composition of the present invention is ≥0.25%, stainless steel used to make thermos flask liners is less prone to cracking and has a higher pass rate. Because C and N are both austenite-stabilizing elements, they can inhibit the formation of deformation-induced martensite, reducing local stress concentration caused by phase transformation during deep drawing and lowering cracking tendency. In the system of the present invention, when the combined mass percentage of C+N is ≥0.25%, austenite stability and strength are balanced, achieving optimal crack resistance.

[0014] Preferably, the chemical composition includes the following mass percentages: C 0.07%, Si 0.4%, Mn 8.3%, S 0.009%, P 0.04%, Ni 2.5%, Cr 16.3%, Cu 0.7%, N 0.18%, rare earth 0.15%, Mo 0.6%, Ti 0.3%, and the balance is Fe, wherein the rare earth includes Y, La and Er, and the mass ratio of Y, La and Er is 1:1.4:0.5.

[0015] A second aspect of the present invention provides a method for preparing high corrosion-resistant and high ductility stainless steel, comprising the following steps:

[0016] (1) Melting and casting: Weigh the raw materials according to the mass percentage of each element in the stainless steel, melt them in a medium frequency induction furnace under a nitrogen atmosphere, cool them down for refining, and cast them into ingots after refining;

[0017] (2) Forging and blanking: the ingot is forged and blanked to obtain a forging blank;

[0018] (3) Hot rolling: Heat the forging blank in a nitrogen atmosphere, perform rough rolling first, and then perform finish rolling;

[0019] (4) Solution treatment: Solution treatment is performed after finishing rolling in a nitrogen atmosphere;

[0020] (5) Cold rolling: After the solution treatment, cold rolling is performed to obtain a cold-rolled sheet;

[0021] (6) Cryogenic treatment: cryogenic treatment with liquid nitrogen;

[0022] (7) Aging treatment: Aging treatment is carried out after cryogenic treatment to obtain stainless steel with high corrosion resistance and high ductility.

[0023] Preferably, in step (1), the smelting is carried out at 1600-1650° C. for 80-90 min in a medium frequency induction furnace under a nitrogen atmosphere, and the temperature is lowered to 1550-1600° C. for refining for 60-70 min.

[0024] Preferably, the conditions for forging in step (2) are: preheating the ingot to 1200-1250°C, holding time 1.5-2h / 100mm thickness, total forging ratio ≥3:1, single pass deformation ≤30%, and air cooling.

[0025] Preferably, the rough rolling conditions in step (3) are: single-pass deformation of 15%-20%, rough rolling final rolling temperature ≥1000°C, and rough rolling to 40mm.

[0026] Preferably, in step (3), the finishing rolling temperature is 850-950°C, and the finishing rolling is performed to 4.5 mm.

[0027] Preferably, the conditions for the solution treatment in step (4) are: temperature 1050-1100°C, holding time 20-30 min / mm thickness, and air cooling.

[0028] Preferably, the cold rolling forming conditions in step (5) are: single-pass reduction rate 10%-20%, after each 30%-40% cold rolling deformation, intermediate annealing: 800-850℃ insulation for 10-15min, cold rolling to 0.4mm.

[0029] Preferably, the liquid nitrogen cryogenic conditions in step (6) are: -196°C for 1-2 hours; cooling rate 2-5°C / min, and temperature return rate 2-5°C / min to room temperature.

[0030] Preferably, the aging treatment conditions in step (7) are: keeping at 400-600°C for 1-2 hours, and air cooling to room temperature.

[0031] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0032] 1. This invention provides a highly corrosion-resistant and ductile stainless steel. By optimizing its chemical composition, it achieves significant breakthroughs in improving its mechanical properties and corrosion resistance. This new stainless steel exhibits excellent processing properties and structural stability when used in the manufacture of thermos flask liners, effectively avoiding the cracking common in traditional materials during use. It has broad industrial application prospects and significant practical significance.

[0033] 2. This invention significantly improves the mechanical properties and corrosion resistance of stainless steel through a specific preparation process. This is not only a major breakthrough in materials processing technology, but also provides solid technical support for the application of stainless steel in multiple high-end fields. By using hot-rolling followed by solution treatment at a specific temperature to balance the tensile strength and elongation at break of the stainless steel, the invention ensures that the inner liner of the thermos bottle has both high strength and good ductility. DETAILED DESCRIPTION

[0034] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0035] Example 1: This example provides a highly corrosion-resistant and ductile stainless steel, comprising the following chemical components in mass percentage: C 0.07%, Si 0.4%, Mn 8.3%, S 0.009%, P 0.04%, Ni 2.5%, Cr 16.3%, Cu 0.7%, N 0.18%, rare earth 0.15%, Mo 0.6%, Ti 0.3%, and the balance is Fe, wherein the rare earths include Y, La and Er, and the mass ratio of Y, La and Er is 1:1.4:0.5.

[0036] The method for preparing the above-mentioned high corrosion-resistant and high ductility stainless steel comprises the following steps:

[0037] (1) Melting and casting: The raw materials are weighed according to the mass percentage of each element in the stainless steel, melted in a medium frequency induction furnace at 1620℃ for 85min under a nitrogen atmosphere, cooled to 1560℃ and refined for 65min. After refining, the raw materials are cast into ingots;

[0038] (2) Forging: The ingot is forged, with a total forging ratio of 3:1, a single-pass deformation of 30%, and air cooling to obtain a forging blank;

[0039] (3) Hot rolling: In a nitrogen atmosphere, the forging billet is heated to 1170 ° C, kept warm for 1.5 hours, and then rough rolled with a single-pass deformation of 18%. The rough rolling temperature is 1000 ° C, and the rough rolling is carried out to 40 mm. The finishing rolling temperature is 900 ° C, and the finishing rolling is carried out to 4.5 mm.

[0040] (4) Solution treatment: in nitrogen atmosphere, 1070℃, holding time 25min / mm thickness, air cooling;

[0041] (5) Cold rolling: single pass reduction rate 18%, after each 35% cold rolling deformation, intermediate annealing: 820℃ holding time 12min, cold rolling to 0.4mm, to obtain cold rolled sheet;

[0042] (6) Cryogenic treatment: conventionally cryogenic treatment is performed using liquid nitrogen, with a temperature of -196°C for 1.5 h; the cooling rate is 3°C / min, and the temperature return rate is 4°C / min to room temperature;

[0043] (7) Aging treatment: keep the temperature at 500℃ for 1.5h, and then air cool to room temperature to obtain high corrosion resistance and high ductility stainless steel.

[0044] Example 2: This example provides a highly corrosion-resistant and ductile stainless steel, comprising the following chemical components in mass percentage: C 0.09%, Si 0.2%, Mn 9%, S 0.001%, P 0.05%, Ni 2%, Cr 17%, Cu 1.5%, N 0.17%, rare earth 0.12%, Mo 1.0%, Ti 0.3%, and the remainder is Fe, wherein the rare earths include Y, La and Er, and the mass ratio of Y, La and Er is 1:1.3:0.6.

[0045] The method for preparing the above-mentioned high corrosion-resistant and high ductility stainless steel comprises the following steps:

[0046] (1) Melting and casting: The raw materials are weighed according to the mass percentage of each element in the stainless steel, melted in a medium frequency induction furnace at 1600 ° C for 90 minutes under a nitrogen atmosphere, cooled to 1550 ° C for refining for 70 minutes, and cast into ingots after refining;

[0047] (2) Forging: The ingot is forged, with a total forging ratio of 3:1, a single-pass deformation of 30%, and air cooling to obtain a forging blank;

[0048] (3) Hot rolling: In a nitrogen atmosphere, heat the forging billet to 1150 ° C, keep it warm for 2 hours, and then perform rough rolling with a single-pass deformation of 15%. The final rolling temperature of the rough rolling is 1000 ° C, and the rough rolling is carried out to 40 mm. The final rolling temperature of the finishing rolling is 950 ° C, and the finishing rolling is carried out to 4.5 mm.

[0049] (4) Solution treatment: in nitrogen atmosphere, 1050 ° C, holding time 30 min / mm thickness, air cooling;

[0050] (5) Cold rolling: single pass reduction rate 10%, after each 40% cold rolling deformation, intermediate annealing: 800℃ holding time 15min, cold rolling to 0.4mm, to obtain cold rolled sheet;

[0051] (6) Cryogenic treatment: conventionally cryogenic treatment is performed using liquid nitrogen, with a temperature of -196°C for 1 hour; the cooling rate is 5°C / min, and the temperature return rate is 2°C / min to room temperature;

[0052] (7) Aging treatment: keep at 600℃ for 1h, air cool to room temperature to obtain high corrosion resistance and high ductility stainless steel.

[0053] Example 3: This example provides a highly corrosion-resistant and ductile stainless steel, comprising the following chemical components in mass percentage: C 0.09%, Si 0.7%, Mn 7%, S 0.02%, P 0.03%, Ni 2.5%, Cr 17%, Cu 0.7%, N 0.2%, rare earth 0.12%, Mo 0.55%, Ti 0.4%, and the remainder is Fe, wherein the rare earths include Y, La and Er, and the mass ratio of Y, La and Er is 1:1.5:0.4.

[0054] The method for preparing the above-mentioned high corrosion-resistant and high ductility stainless steel comprises the following steps:

[0055] (1) Melting and casting: The raw materials are weighed according to the mass percentage of each element in the stainless steel, melted at 1650℃ for 80min in a medium frequency induction furnace under a nitrogen atmosphere, cooled to 1600℃ and refined for 60min. After refining, the raw materials are cast into ingots;

[0056] (2) Forging: The ingot is forged, with a total forging ratio of 3:1, a single-pass deformation of 30%, and air cooling to obtain a forging blank;

[0057] (3) Hot rolling: In a nitrogen atmosphere, heat the forging billet to 1200 ° C, keep it warm for 1 hour, and then perform rough rolling with a single-pass deformation of 20%. The final rolling temperature of the rough rolling is 1000 ° C, and the rough rolling is carried out to 40 mm. The final rolling temperature of the finishing rolling is 850 ° C, and the finishing rolling is carried out to 4.5 mm.

[0058] (4) Solution treatment: in nitrogen atmosphere, 1100 ° C, holding time 20 min / mm thickness, air cooling;

[0059] (5) Cold rolling: single pass reduction rate 20%, after every 30% cold rolling deformation, intermediate annealing: 850 ° C for 10 minutes, cold rolling to 0.4 mm, to obtain cold rolled sheet;

[0060] (6) Cryogenic treatment: conventionally cryogenic treatment is performed using liquid nitrogen, with a temperature of -196°C for 2 h; the cooling rate is 2°C / min, and the temperature return rate is 5°C / min to room temperature;

[0061] (7) Aging treatment: keep the temperature at 400℃ for 2h, and then air cool to room temperature to obtain high corrosion resistance and high ductility stainless steel.

[0062] Comparative Example 1: The difference between this comparative example and Example 1 is: a highly corrosion-resistant and highly ductile stainless steel, comprising the following chemical components in mass percentage: C 0.02%, Si 0.8%, Mn 10%, S 0.25%, P 0.08%, Ni 4.5%, Cr 15.1%, Cu 0.3%, N 0.1%, rare earth 0.12%, Mo 2.0%, Ti 0.1%, and the balance is Fe, wherein the rare earths include Y, La and Er, and the mass ratio of Y, La and Er is 1:1.4:0.5.

[0063] Comparative Example 2: The difference between this comparative example and Example 1 is that the chemical composition ratio commonly used in the current prior art for preparing stainless steel thermos flask liners is as follows:

[0064] A high-corrosion-resistant and high-ductility stainless steel comprises the following chemical components in percentage by mass: C0.05%, Si0.5%, Mn9.5%, P0.025%, S0.005%, Cr14.55%, Ni1.58%, Cu1.54%, and the balance is Fe.

[0065] Comparative Example 3: The difference between this comparative example and Example 1 is that the mass percentage of C+N is different.

[0066] Specifically: a highly corrosion-resistant and ductile stainless steel, comprising the following chemical components in mass percentage: C 0.03%, Si 0.4%, Mn 8.3%, S 0.009%, P 0.04%, Ni 2.5%, Cr 16.3%, Cu 0.7%, N 0.12%, rare earth 0.15%, Mo 0.6%, Ti 0.3%, and the balance is Fe, wherein the rare earths include Y, La and Er, and the mass ratio of Y, La and Er is 1:1.4:0.5.

[0067] Comparative Example 4: The difference between this comparative example and Example 1 is that only Y is added as rare earth.

[0068] A high-corrosion-resistant and high-ductility stainless steel comprises the following chemical components in mass percentage: C 0.07%, Si 0.4%, Mn 8.3%, S 0.009%, P 0.04%, Ni 2.5%, Cr 16.3%, Cu 0.7%, N 0.18%, rare earth Y 0.15%, Mo 0.6%, Ti 0.3%, and the balance is Fe.

[0069] Comparative Example 5: The difference between this comparative example and Example 1 is that the rare earths include Y and La.

[0070] A high-corrosion-resistant and high-ductility stainless steel comprises the following chemical components in percentage by mass: C 0.07%, Si 0.4%, Mn 8.3%, S 0.009%, P 0.04%, Ni 2.5%, Cr 16.3%, Cu 0.7%, N 0.18%, rare earth 0.15%, Mo 0.6%, Ti 0.3%, and the balance is Fe. The rare earth comprises Y and La, and the mass ratio of Y to La is 1:1.4.

[0071] Comparative Example 6: This comparative example differs from Example 1 in the mass ratio of Y, La, and Er. A highly corrosion-resistant and ductile stainless steel comprises the following chemical composition in mass percentage: C 0.07%, Si 0.4%, Mn 8.3%, S 0.009%, P 0.04%, Ni 2.5%, Cr 16.3%, Cu 0.7%, N 0.18%, rare earth 0.15%, Mo 0.6%, Ti 0.3%, and the balance Fe. The rare earths include Y, La, and Er, and the mass ratio of Y, La, and Er is 0.5:1:1.4.

[0072] Comparative Example 7: The difference between this comparative example and Example 1 is that the mass percentages of Mo, Cu and rare earth are different.

[0073] A high-corrosion-resistant and high-ductility stainless steel comprises the following chemical components in percentage by mass: C 0.07%, Si 0.4%, Mn 8.3%, S 0.009%, P 0.04%, Ni 2.5%, Cr 16.3%, Cu 0.8%, N 0.18%, rare earth 0.05%, Mo 1.5%, Ti 0.3%, and the balance is Fe. The rare earths include Y, La, and Er, and the mass ratio of Y, La, and Er is 1:1.4:0.5.

[0074] Comparative Example 8: The difference between this comparative example and Example 1 is that the conditions for the solution treatment in step (4) are: temperature 1020°C, holding time 25 min / mm thickness.

[0075] Comparative Example 9: The difference between this comparative example and Example 1 is that the conditions for the solution treatment in step (4) are: temperature 1150°C, holding time 25 min / mm thickness.

[0076] Performance test: Performance test was performed on the high corrosion-resistant and high ductility stainless steel prepared in Examples 1-3 and Comparative Examples 1-9.

[0077] 1. Tensile strength, yield strength, and elongation after fracture: Refer to GB / T 228.1-2021 Metallic Materials Tensile Tests Part 1: Room Temperature Test Methods. Results are shown in Table 1.

[0078] 2. Corrosion resistance: Referring to GB / T 10124-1988, stainless steel pipes were placed in a 30% by mass hydrochloric acid solution at room temperature (25°C) for 72 hours, and the degree of corrosion was tested. The results are shown in Table 1.

[0079] 3. Stainless steel pipes were welded at 1200°C, held at 1010°C for 20 minutes / mm, and then hydro-expanded using 100 MPa high-pressure water at room temperature to form thermos liner. The number of samples exhibiting hydro-expansion cracking was counted among 200 samples. The results are shown in Table 1.

[0080] .

[0081] As shown in Table 1, the stainless steels of Examples 1-3 have excellent mechanical properties and good corrosion resistance, and the inner liner of the thermos cup prepared therefrom is not prone to cracking.

[0082] In Comparative Example 1, the ratio of element composition was changed, and the comprehensive performance of stainless steel decreased. Comparative Example 2 is the element ratio of the stainless steel liner in the prior art. From the results, it can be found that the failure rate caused by cracking is high, and the corrosion resistance effect is poor.

[0083] In Comparative Example 3, when the combined mass percentage of C+N was less than 0.25%, the stainless steel used to make the thermos flask liner easily cracked, and the qualified rate decreased. Compared with Comparative Example 3, Example 1 has a higher total amount of C+N. Both C and N are interstitial solid solution strengthening elements. Their atoms embed into the iron lattice, increasing the resistance to dislocation movement and improving tensile strength. The addition of C and N also optimizes the stability of austenite, improving both strength and plasticity.

[0084] In Comparative Examples 4-6, the composition ratios of rare earths are different, and the tensile strength of the stainless steel decreases.

[0085] In Comparative Example 7, the mass percentage of Mo is greater than the sum of the mass percentages of Cu and rare earth, and the corrosion resistance of the stainless steel decreases.

[0086] The solution treatment conditions in Comparative Examples 8 and 9 are different. In Comparative Example 8, the solution treatment temperature is lower than 1050°C, and the elongation after fracture decreases. In Comparative Example 9, the solution treatment temperature is higher than 1100°C, and the tensile strength decreases. During the test, it was found that the higher the solution treatment temperature, the lower the tensile strength of the stainless steel. The tensile strength can only be higher than 800MPa when the temperature is less than or equal to 1100°C. The elongation after fracture is proportional to the solution treatment temperature. When the temperature is greater than or equal to 1050°C, the elongation after fracture of the stainless steel is ≥40%, which can meet the requirements for the inner liner of a stainless steel thermos cup.

[0087] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A high corrosion-resistant and high ductility stainless steel, characterized in that: The chemical composition includes the following percentages by mass: C 0.07%, Si 0.4%, Mn 8.3%, S 0.009%, P 0.04%, Ni 2.5%, Cr 16.3%, Cu 0.7%, N 0.18%, rare earth 0.15%, Mo 0.6%, Ti 0.3%, and the balance is Fe, wherein the rare earth includes Y, La and Er, and the mass ratio is 1:1.4:0.5; The method for preparing the highly corrosion-resistant and highly ductile stainless steel comprises: (1) Melting and casting: The raw materials are weighed according to the mass percentage of each element in the stainless steel, melted in a medium frequency induction furnace under a nitrogen atmosphere, cooled and refined, and cast into ingots after refining; (2) Forging and blanking: the ingot is forged and blanked to obtain a forging blank; (3) Hot rolling: In a nitrogen atmosphere, the forging blank is heated, firstly rough rolled, and then finished rolled; (4) Solution treatment: Solution treatment is performed after finishing rolling in a nitrogen atmosphere under the following conditions: temperature 1050-1100°C, holding time 20-30 min / mm thickness, and air cooling; (5) Cold rolling: After the solution treatment, cold rolling is performed to obtain a cold-rolled sheet; (6) Cryogenic treatment: cryogenic treatment with liquid nitrogen; (7) Aging treatment: Aging treatment is performed after cryogenic treatment to obtain stainless steel with high corrosion resistance and high ductility.

2. The high corrosion-resistant and high ductility stainless steel according to claim 1, characterized in that: In the step (1), under a nitrogen atmosphere, the smelting is carried out at 1600-1650° C. in a medium frequency induction furnace for 80-90 minutes, and the temperature is lowered to 1550-1600° C. for refining for 60-70 minutes.

3. The high corrosion-resistant and high ductility stainless steel according to claim 2, characterized in that: The cold rolling forming conditions in step (5) are: single pass reduction rate 10%-20%, after each 30%-40% cold rolling deformation, intermediate annealing: 800-850℃ insulation for 10-15min, cold rolling to 0.4mm.

4. The high corrosion-resistant and high ductility stainless steel according to claim 3, characterized in that: The conditions for deep cooling with liquid nitrogen in step (6) are: keeping at -196°C for 1-2 hours; cooling rate 2-5°C / min, and returning to room temperature at a rate of 2-5°C / min.

5. The high corrosion-resistant and high ductility stainless steel according to claim 4, characterized in that: The aging treatment conditions in step (7) are: keeping at 400-600°C for 1-2 hours, and air cooling to room temperature.