Production process of high tensile and yield strength stainless steel strip

Abstract

The present invention provides a production process of stainless steel strip with high tensile strength and yield strength, comprising: selecting a stainless steel cold-rolled strip; pre-rolling and annealing the stainless steel cold-rolled strip; sending the stainless steel cold-rolled strip after pre-rolling and annealing to a first rolling mill for rough rolling to obtain a rough-rolled strip, and the total reduction rate of rough rolling is 50% to 62.5%; intermediate annealing the rough-rolled strip; sending the rough-rolled strip after intermediate annealing to a second rolling mill for finish rolling to obtain a finished strip, and the total reduction rate of finish rolling is 75% to 83.3%; cleaning the finished strip and stress relieving annealing; stretching and straightening the finished strip after stress relieving annealing; sending the finished strip after stretching and straightening to a third rolling mill for tail rolling to obtain a finished strip, and the total reduction rate of tail rolling is 20±2%. The production process of stainless steel strip with high tensile strength and yield strength provided by the present invention can improve the tensile strength and yield strength of the finished stainless steel strip.

Description

Technical Field

[0001] The invention belongs to the technical field of stainless steel strips, and in particular relates to a production process of stainless steel strips with high tensile strength and yield strength. Background Art

[0002] Stainless steel strip is an extension made by rolling stainless steel thin strip. It has good corrosion resistance, high temperature resistance and high strength and toughness and is widely used in the automotive industry and precision electronic products. With the advancement of industrial technology, the tensile and yield strength requirements of stainless steel materials in high-end fields such as automobiles and electronics are getting higher and higher. The tensile strength of austenitic stainless steel strip currently developed can only reach 800MPa, and the yield strength can reach up to 450Mpa. It is currently known that increasing the nitrogen content can help improve the strength of the product. For example, increasing the nitrogen content to more than 0.5% can increase the tensile strength of stainless steel materials to more than 1000Mpa and the yield strength to more than 600Mpa. However, it is very difficult to actually produce high-nitrogen steel, and there is currently no mature processing technology.

[0003] At present, in order to achieve the purpose of high strength, most of the improvements are still made from the strip rolling process, using the transformation of residual austenite to martensite in the TRIP (transformation induced plasticity) effect to improve the performance of strip products. For example, the existing patent CN109837470A, a high-strength nitrogen-containing economical austenitic stainless steel, obtains nano-scale grains by cold rolling and flexible annealing processes, improves material strength and maintains high plasticity, but it has high requirements for the continuous casting of stainless steel strips, and at the same time, Mn elements with a weight ratio of more than 8% are added to the composition, which easily leads to high-temperature austenite in the strip and affects the uniformity of the organization, thereby affecting the formability of the strip. Summary of the invention

[0004] The embodiment of the present invention provides a production process of a stainless steel strip with high tensile strength and yield strength, aiming to improve the tensile strength and yield strength of the stainless steel strip.

[0005] To achieve the above object, the technical solution adopted by the present invention is: to provide a production process of high tensile and yield strength stainless steel strip, comprising:

[0006] Select a stainless steel cold-rolled strip with a thickness of 0.8 to 2.0 mm;

[0007] Performing pre-rolling annealing on the stainless steel cold-rolled strip;

[0008] The stainless steel cold-rolled strip after pre-rolling and annealing is sent to the first rolling mill for rough rolling to obtain rough-rolled strip steel, and the total reduction rate of rough rolling is 50% to 62.5%;

[0009] The rough rolled strip is subjected to intermediate annealing;

[0010] The rough-rolled steel strip after intermediate annealing is sent to the second rolling mill for finishing rolling to obtain the finished steel strip. The total reduction rate of finishing rolling is 75% to 83.3%.

[0011] The finished rolled steel strip is cleaned and then subjected to stress relief annealing;

[0012] The finished rolled strip after stress relief annealing is subjected to stretching and straightening;

[0013] The finished strip after drawing, straightening and shaping is sent to the third rolling mill for tail rolling to obtain a finished strip with a thickness of 0.04 to 0.16 mm. The total reduction rate of the tail rolling is 20±2%.

[0014] In a possible implementation, the inlet tension of the tail rolling is 320-410 kN, the outlet tension is 290-350 kN, the rolling force is 5500-6100 kN, and the rolling speed is 180-220 m / min.

[0015] In some embodiments, the tension of the tension-leveling forming is 40-90 kN, and the elongation of the tension-leveling forming is 0.55%-0.75%.

[0016] Exemplarily, the pre-rolling annealing, the intermediate annealing and the stress relief annealing are all performed in a vacuum annealing furnace, and hydrogen and / or nitrogen are introduced into the vacuum annealing furnace as protective gas.

[0017] For example, the annealing temperature of the pre-rolling annealing is 750-850° C., and the annealing time is 45-120 seconds; the annealing temperature of the intermediate annealing is 900-980° C., and the annealing time is 30-90 seconds.

[0018] In a possible implementation, the stress relief annealing after cleaning the finished rolled steel strip includes:

[0019] Degreasing the finished steel strip by using an alkaline degreasing agent;

[0020] Electrolytically treating the degreased finished strip in an electrolytic pickling solution;

[0021] The electrolytically treated finished rolled steel strip is pickled with a mixed acid solution;

[0022] The pickled finished steel strip is subjected to hot air drying;

[0023] The finished rolled strip after hot air drying is subjected to stress relief annealing, the annealing temperature of the stress relief annealing is 1020-1075°C, and the annealing time is 30-50s.

[0024] Specifically, the ambient temperature for degreasing treatment is 85-95°C; the electrolytic pickling solution includes sulfuric acid and nitric acid added in a ratio of 1.2-1.5:2, and the ambient temperature for electrolysis treatment is 80-85°C; the mixed acid solution includes nitric acid and hydrofluoric acid added in a ratio of 1-1.2:3, and the ambient temperature for pickling treatment is 70-75°C; the hot air temperature for hot air drying treatment is 105-115°C.

[0025] For example, the weight percentage of the components of stainless steel cold-rolled strip is: C: 0.06~0.12%, Si: 0.5~1.2%, Mn: 0.1~0.9%, Cr: 15.7~17.7%, Ni: 1.0~2.5%; N: 0.03~0.1%, P≤0.05%, S≤0.01%, Mo: 0.25~0.4%, and the rest is Fe and unavoidable impurities.

[0026] Exemplarily, the tensile strength of the finished steel strip is 910-1100 MPa, the yield strength is 570-710 MPa, and the elongation at break is ≥45%.

[0027] The beneficial effect of the high tensile strength and yield strength stainless steel strip production process provided by the present invention is that: compared with the prior art, the high tensile strength and yield strength stainless steel strip production process of the present invention performs pre-rolling annealing on the stainless steel cold-rolled steel strip before rough rolling to reduce its hardness, and then performs rough rolling on the stainless steel cold-rolled strip blank at a total reduction rate of 50% to 62.5% to obtain a rough-rolled strip, after the rough rolling is completed, the rough-rolled strip is softened again by intermediate annealing, and then is fine-rolled at a total reduction rate of 75% to 83.3% to obtain a fine-rolled strip, and then the fine-rolled strip is cleaned and stress-relieved annealed to eliminate the internal stress of the fine-rolled strip, and then the internal grain distribution of the fine-rolled strip is isotropically distributed by stretching and straightening, and on this basis, a finished strip with a uniform and dense internal grain distribution and consistent orientation is obtained through a tail rolling process with a total reduction rate of 20±2%, thereby improving the tensile strength and yield strength of the finished strip. DETAILED DESCRIPTION

[0028] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail in the following embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0029] It should be noted that the terms "length", "width", "upper", "lower", "front", "back", "top", "bottom", "inside", "outside" and the like indicating the orientation or positional relationship are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. The terms "first", "second" and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second" and "third" may explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0030] The production process of high tensile strength and yield strength stainless steel strip provided by the present invention is now described. The production process of high tensile strength and yield strength stainless steel strip comprises the following steps:

[0031] Step S100, selecting a stainless steel cold-rolled strip with a thickness of 0.8 to 2.0 mm;

[0032] Step S200, pre-rolling and annealing the stainless steel cold-rolled strip;

[0033] Step S300, sending the pre-rolled annealed stainless steel cold-rolled strip to a first rolling mill for rough rolling to obtain a rough-rolled strip steel, wherein the total reduction ratio of the rough rolling is 50% to 62.5%;

[0034] Step S400, performing intermediate annealing on the rough-rolled steel strip;

[0035] Step S500, sending the rough-rolled steel strip after intermediate annealing to a second rolling mill for finish rolling to obtain a finished steel strip, wherein the total reduction ratio of the finish rolling is 75% to 83.3%;

[0036] Step S600, cleaning the finished rolled steel strip and then performing stress relief annealing;

[0037] Step S700, stretching and straightening the finished steel strip after stress relief annealing;

[0038] Step S800, sending the finished steel strip after drawing, straightening and shaping to the third rolling mill for tail rolling to obtain a finished steel strip with a thickness of 0.04-0.16 mm, and the total reduction rate of the tail rolling is 20±2%.

[0039] It should be explained that the above-mentioned stainless steel cold-rolled strip has a hardness grade of 1 / 2H and above, and is subjected to pre-rolling annealing before rough rolling to reduce its hardness grade to 1 / 4H and below. The first rolling mill adopts a five- to seven-roll rolling mill with an inlet tension of 200-300kN, an outlet tension of 400-550kN, a rolling force of 9200-9900kN, a rolling speed of 50-80m / min, and a total reduction rate, that is, the sum of the reduction rates of each roll of the first rolling mill is 50%-62.5%. Thus, a stainless steel cold-rolled strip with a thickness of 0.8-2.0mm can be subjected to rough rolling to obtain a rough-rolled strip with a thickness of 0.4-1.0mm; pre-rolling annealing can soften the stainless steel cold-rolled strip, which can increase the reduction rate of each pass of the first rolling mill from the perspective of increasing the rolling force and reducing the tension reduction rate, thereby reducing the number of roll passes of the first rolling mill and improving the rough rolling efficiency.

[0040] The rough-rolled steel strip obtained after rough rolling reaches the hardness grade of 1 / 2H or above again, so the hardness grade of the rough-rolled strip is reduced to 1 / 4H or below through intermediate annealing and then enters the second rolling mill for finishing rolling. The second rolling mill adopts a twenty-high rolling mill with an inlet tension of 300-370kN, an outlet tension of 480-570kN, a rolling force of 8100-8700kN, a rolling speed of 120-210m / min, and a sum of the reduction rates of each roll of 75%-83.3%. Finally, a finished strip with a thickness of 0.05-0.2mm is obtained, and a total reduction rate of 20±2% is retained for the final tail rolling process to obtain a finished strip with a thickness of 0.04-0.16mm. In this second rolling mill, higher tension, lower rolling force and higher rolling speed are used for finishing rolling. On the one hand, by increasing the finishing rolling tension, it is beneficial for the rough-rolled steel strip to obtain a larger elongation during the finishing rolling process. The specific elongation is controlled at 0.7% to 0.85%. Too large an elongation increases the risk of strip breakage, which can increase the amount of grain dislocation slip, thereby causing the finished strip to undergo a TRIP effect and obtain higher tensile strength and yield strength. On the other hand, it is beneficial to improve the finishing efficiency of the rough-rolled strip.

[0041] In addition, during the finishing process, due to the higher tension and relatively small rolling force, all the grains are dislocated and slipped in the axial direction, that is, the length direction of the strip, so that the grain distribution direction can be consistent, thereby promoting the uniformity of the internal stress of the finished strip. On this basis, the finished strip is subjected to stress relief annealing, which can largely eliminate the plate defects such as unevenness caused by uneven internal stress distribution of the finished strip. After the stress relief annealing is completed, the plate quality of the finished strip is further optimized by stretching and straightening.

[0042] Since the finishing strip retains the tail rolling reduction rate, the finishing strip after drawing and straightening is sent to the third rolling mill for tail rolling with a total reduction rate of 20±2%. The third rolling mill adopts a three- to five-roll mill. Since stress relief annealing can soften the finishing strip from the hardness grade of 1 / 2H and above after finishing rolling to the hardness grade of 1 / 4H, the tail rolling can roll and shape the grain idiosyncratic dislocation slip caused by the TRIP effect of the finishing strip, thereby improving the stability of the grain state.

[0043] It should be understood that, in this embodiment, the elongation at break of the finished strip can be improved by three annealings of pre-rolling annealing, intermediate annealing and stress relief annealing. On this basis, the total elongation of the stainless steel cold-rolled strip to the finished strip in the entire rolling process is increased by adjusting the tension, rolling force and rolling speed of the first rolling mill, the second rolling mill and the third rolling mill. In this way, the elongation at break of the finished strip can be maintained above 45% on the basis of improving the tensile strength and yield strength of the finished strip.

[0044] Compared with the prior art, the production process of high tensile strength and yield strength stainless steel strip provided in the present embodiment is as follows: before rough rolling, the stainless steel cold-rolled steel strip is pre-rolled and annealed to reduce its hardness; then, the stainless steel cold-rolled strip is rough-rolled at a total reduction rate of 50% to 62.5% to obtain a rough-rolled strip; after the rough rolling is completed, the rough-rolled strip is softened again by intermediate annealing and then fine-rolled at a total reduction rate of 75% to 83.3% to obtain a fine-rolled strip; then, the fine-rolled strip is cleaned and stress-relieved and annealed to eliminate the internal stress of the fine-rolled strip; then, the internal grain distribution of the fine-rolled strip is isotropically oriented by stretching and straightening; on this basis, a finished strip with a uniform and dense internal grain distribution and consistent orientation is obtained by a tail rolling process with a total reduction rate of 20±2%, thereby improving the tensile strength and yield strength of the finished strip.

[0045] In some embodiments, the entrance tension of the tail rolling is 320-410 kN, the exit tension is 290-350 kN, the rolling force is 5500-6100 kN, and the rolling speed is 180-220 m / min. The purpose of the tail rolling is to improve the crystal phase stability of the finished strip by utilizing the reduction margin after the finishing rolling, that is, the total reduction rate of 20±2%. Due to the softening effect of stress relief annealing on the finished strip, a smaller rolling force can be used for tail rolling relative to the finishing process to reduce roller wear. The tail rolling can transform the finished strip with a hardness grade of 1 / 4H into a finished strip with a hardness grade of 1 / 2H.

[0046] In some possible implementations, the tension of the straightening process is 40-90 kN, and the elongation of the straightening process is 0.55%-0.75%. Since the finished strip has a high tensile strength, a higher tension is used here than the conventional straightening process (tension 10-50 kN). At the same time, the straightening process is set after the stress relief annealing, which can make the grain distribution inside the finished strip more uniform and dense, thereby obtaining better plate quality and crystal phase stability.

[0047] Specifically, in this embodiment, the pre-rolling annealing, intermediate annealing and stress relief annealing are all performed in a vacuum annealing furnace, and hydrogen and / or nitrogen are introduced into the vacuum annealing furnace as protective gas. Specifically, a mixed gas of hydrogen and nitrogen can be preferably used, and the concentration ratio of hydrogen to nitrogen is 3:1.

[0048] Optionally, in this embodiment, the annealing temperature of the pre-rolling annealing is 750-850°C, and the annealing time is 45-120s; the annealing temperature of the intermediate annealing is 900-980°C, and the annealing time is 30-90s. The corresponding annealing temperature and annealing time are selected according to the thickness of the stainless steel cold-rolled strip. Specifically, the thicker the stainless steel cold-rolled strip, the higher the annealing temperature and the longer the time. However, for the stainless steel cold-rolled strip of the same thickness, the shorter the annealing time, the more conducive to the occurrence of the TRIP effect. Therefore, each annealing time in this embodiment is shorter than the conventional annealing time.

[0049] In a possible implementation, the stress relief annealing after cleaning the finished rolled steel strip includes:

[0050] Degreasing the finished steel strip by using an alkaline degreasing agent;

[0051] Electrolytically treating the degreased finished strip in an electrolytic pickling solution;

[0052] The electrolytically treated finished rolled steel strip is pickled with a mixed acid solution;

[0053] The pickled finished steel strip is subjected to hot air drying;

[0054] The finished rolled strip after hot air drying is subjected to stress relief annealing, the annealing temperature of the stress relief annealing is 1020-1075°C, and the annealing time is 30-50s.

[0055] The alkaline degreasing agent is used to remove saponified grease on the surface of the finished steel strip. The non-saponifiable pollutants such as phosphate stains adhering to the surface of the finished steel strip are then ionized and decomposed by electrolysis. Finally, the ionized and decomposed non-saponifiable pollutants are washed away by pickling. The surface of the finished steel strip is then dried by hot air blowing and then stress relief annealing is performed to avoid the formation of yellow spots, stains and other appearance defects on the surface of the finished steel strip during the stress relief annealing process.

[0056] On this basis, a higher annealing temperature and a shorter annealing time are used during stress relief annealing of the finished strip, which can effectively reduce grain boundary diffusion and increase the driving force of the TRIP effect, so that stress relief annealing can bring a gain effect on the tensile strength and yield strength of the finished strip.

[0057] Specifically, the ambient temperature of the above-mentioned degreasing treatment is 85-95°C; the electrolytic pickling solution includes sulfuric acid and nitric acid added in a ratio of 1.2-1.5:2, and the ambient temperature of the electrolytic treatment is 80-85°C; the mixed acid solution includes nitric acid and hydrofluoric acid added in a ratio of 1-1.2:3, and the ambient temperature of the pickling treatment is 70-75°C; the hot air temperature of the hot air drying treatment is 105-115°C.

[0058] At an ambient temperature of 85-95°C, it is more conducive for the alkaline degreasing agent to remove saponified grease on the surface of the finished strip, and at the same time, it can avoid the evaporation of water on the surface of the finished strip, which increases the difficulty of degreasing; the electrolytic pickling solution is added with sulfuric acid and nitric acid in a neutral solution at a ratio of 1.2-1.5:2. The neutral solution can be a 300g / L sodium chloride solution. The final sulfuric acid concentration of the electrolytic pickling solution is controlled at 180-190g / L, and the nitric acid concentration is controlled at 130-140g / L. The pH value of the pickling solution is adjusted to 4.0-4.4; on this basis, at least two ionized metal ions such as iron ions and chromium ions are added in equal amounts to the electrolytic pickling solution, and the metal ion concentration is controlled at 50-55 g / L; the nitric acid concentration in the mixed acid solution is controlled at 120-130 g / L, the hydrofluoric acid concentration is controlled at 40-50 g / L, and at the same time, at least two metal ions with a total concentration of 35-40 g / L are added to the mixed acid solution, wherein the metal ions include chromium ions and nickel ions added in equal proportions.

[0059] It should be noted that the weight percentage of the components of the above-mentioned stainless steel cold-rolled strip is:

[0060] C: 0.06-0.12%, which promotes the formation of austenite and is beneficial to improving the strength of the material, but is not conducive to the elongation performance. Considering that the present embodiment has a high requirement for the elongation of the stainless steel cold-rolled strip, the carbon content is set to no more than 0.12%. At the same time, considering the strength performance of the stainless steel cold-rolled strip, the carbon content is not less than 0.06%.

[0061] Si: 0.5-1.2%. Silicon element is beneficial to improving the strength performance of stainless steel strip.

[0062] Mn: 0.1-0.9%. Manganese is beneficial to improving the strength of the stainless steel strip. At the same time, during the cooling stage of annealing, the solid solubility of manganese is reduced and it is enriched near the grain boundary, thereby promoting the TRIP effect. However, manganese is not conducive to the elongation performance, so the manganese content should be balanced and controlled.

[0063] Cr: 15.7-17.7%. Chromium is mainly used to improve the anti-oxidation and anti-corrosion properties and promote the stability of the crystal phase structure.

[0064] Ni: 0.8-1.2%; Nickel plays a significant role in forming stable austenite and is beneficial to improving elongation performance, but the cost of nickel is relatively high. Therefore, a small amount of nickel is added in consideration of the requirement for a higher elongation of the stainless steel cold-rolled strip in this embodiment.

[0065] N: 0.03-0.1%. Nitrogen can produce an effect close to that of nickel, but its solubility in stainless steel is poor. Too much nitrogen can easily make it impossible to combine with other elements during continuous casting, thereby affecting the quality of stainless steel cold-rolled strip. Therefore, a small amount of nitrogen and a small amount of nickel are selected to improve the elongation performance of stainless steel cold-rolled strip.

[0066] P≤0.05%, phosphorus element should be controlled to the minimum under process conditions.

[0067] S≤0.01%, sulfur element should be controlled to the minimum under process conditions.

[0068] Mo: 0.25-0.4%. The cost of molybdenum is relatively high. Adding a small amount of molybdenum helps to improve the corrosion resistance of stainless steel cold-rolled strip.

[0069] The rest is Fe and unavoidable impurities.

[0070] It should be noted that the tensile strength of the above-mentioned finished strip steel is 910-1100Mpa, the yield strength is 570-710Mpa, and the elongation at break is ≥45%.

[0071] The following tables are relevant test data, among which Table 1, Table 2 and Table 3 are respectively the process parameters of finished strips of different thicknesses processed by the above-mentioned high tensile and yield strength stainless steel strip production process; Table 4 is the product performance parameters of the finished strips obtained by the above-mentioned high tensile and yield strength stainless steel strip production process; Table 5 is the product performance parameters of the finished strips obtained by the existing technology process.

[0072] Table 1: Processing parameters of 0.8mm stainless steel cold rolled strip to 0.04mm finished strip

[0073]

[0074] Table 2: Processing parameters of 1.0 mm stainless steel cold rolled strip to 0.08 mm finished strip

[0075]

[0076] Table 3: Processing parameters of 2.0 mm stainless steel cold rolled strip to 0.16 mm finished strip

[0077]

[0078] Table 4: Performance parameters of finished strip steel with thickness of 0.04mm, 0.08mm and 0.16mm

[0079]

[0080] Table 5: Performance parameters of finished strip steel obtained by using existing process

[0081]

[0082] It can be seen from the test data in Tables 1 to 5 that the finished strip steel obtained by the high tensile strength and yield strength stainless steel strip production process of the present invention has a tensile strength of at least 20% higher, a yield strength of at least 29% higher, and an elongation at break of at least 30% higher than that of the existing process.

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A process for producing high tensile and yield strength stainless steel strip, characterized in that: include: Select a stainless steel cold-rolled strip with a thickness of 0.8 to 2.0 mm; Performing pre-rolling annealing on the stainless steel cold-rolled strip; The stainless steel cold-rolled strip after pre-rolling and annealing is sent to a first rolling mill for rough rolling to obtain a rough-rolled strip steel, wherein the total reduction rate of the rough rolling is 50% to 62.5%; performing intermediate annealing on the rough-rolled steel strip; The rough-rolled steel strip after intermediate annealing is sent to a second rolling mill for finish rolling to obtain a finished steel strip, wherein the total reduction ratio of the finish rolling is 75% to 83.3%; the inlet tension of the second rolling mill is 300 to 370 kN, the outlet tension is 480 to 570 kN, the rolling force is 8100 to 8700 kN, and the rolling speed is 120 to 210 m / min; The finished rolled steel strip is cleaned and then subjected to stress relief annealing; The finished rolled steel strip after stress relief annealing is subjected to stretching and straightening; The finished steel strip after drawing, straightening and shaping is sent to the third rolling mill for tail rolling to obtain a finished steel strip with a thickness of 0.04 to 0.16 mm, and the total reduction rate of the tail rolling is 20±2%.

2. The process for producing high tensile and yield strength stainless steel strip according to claim 1, characterized in that: The inlet tension of the tail rolling is 320-410 kN, the outlet tension is 290-350 kN, the rolling force is 5500-6100 kN, and the rolling speed is 180-220 m / min.

3. The process for producing high tensile and yield strength stainless steel strip according to claim 1, characterized in that: The tension of the tension-leveling forming is 40-90 kN, and the elongation of the tension-leveling forming is 0.55%-0.75%.

4. The process for producing high tensile and yield strength stainless steel strip according to claim 1, characterized in that: The pre-rolling annealing, the intermediate annealing and the stress relief annealing are all performed in a vacuum annealing furnace, and hydrogen and / or nitrogen are introduced into the vacuum annealing furnace as protective gas.

5. The process for producing high tensile and yield strength stainless steel strip according to claim 1, characterized in that: The annealing temperature of the pre-rolling annealing is 750-850° C., and the annealing time is 45-120 seconds; the annealing temperature of the intermediate annealing is 900-980° C., and the annealing time is 30-90 seconds.

6. The process for producing high tensile and yield strength stainless steel strip according to claim 1, characterized in that: The stress relief annealing after cleaning the finished rolled steel strip comprises: Degreasing the finished steel strip using an alkaline degreasing agent; Electrolytically treating the degreased finished steel strip in an electrolytic pickling solution; The finished rolled steel strip after the electrolytic treatment is pickled with a mixed acid solution; The finished rolled steel strip after pickling is subjected to hot air drying; The finished rolled steel strip after hot air drying is subjected to stress relief annealing, the annealing temperature of the stress relief annealing is 1020-1075° C., and the annealing time is 30-50 seconds.

7. The process for producing high tensile and yield strength stainless steel strip according to claim 6, characterized in that: The ambient temperature of the degreasing treatment is 85-95°C; the electrolytic pickling solution includes sulfuric acid and nitric acid added in a ratio of 1.2-1.5:2, and the ambient temperature of the electrolytic treatment is 80-85°C; the mixed acid solution includes nitric acid and hydrofluoric acid added in a ratio of 1-1.2:3, and the ambient temperature of the pickling treatment is 70-75°C; the hot air temperature of the hot air drying treatment is 105-115°C.

8. The process for producing high tensile and yield strength stainless steel strip according to any one of claims 1 to 7, characterized in that: The composition weight percentage of the stainless steel cold-rolled strip is: C: 0.06-0.12%, Si: 0.5-1.2%, Mn: 0.1-0.9%, Cr: 15.7-17.7%, Ni: 1.0-2.5%; N: 0.03~0.1%, P≤0.05%, S≤0.01%, Mo: 0.25~0.4%, and the rest are Fe and unavoidable impurities.

9. The process for producing high tensile and yield strength stainless steel strip according to any one of claims 1 to 7, characterized in that: The finished strip steel has a tensile strength of 910-1100 MPa, a yield strength of 570-710 MPa, and an elongation at break of ≥45%.

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