Processing technology of high-strength corrosion-resistant nitrogen alloyed stainless steel strip

Abstract

The present application relates to the technical field of corrosion-resistant stainless steel preparation, and particularly to a processing technology of high-strength corrosion-resistant nitrogen-alloyed stainless steel strip.The chemical composition of the high-strength corrosion-resistant nitrogen-alloyed stainless steel strip contains the following components in the following mass percentages: 0.25-0.45% of N, 22-26% of Cr, 5-10% of Ni, 2-8% of Mn, 1.8-2.4% of Mo, 0.05-0.2% of V, 0.05-0.2% of Cu, 0.05-0.2% of Ti, 0.01-0.04% of Nb, ≤0.02% of Al, ≤0.05% of C, ≤1.0% of Si, ≤0.030% of P, ≤0.01% of S, ≤0.005% of O, and the balance of Fe and inevitable impurities.The pitting corrosion resistance equivalent of the stainless steel strip is greater than or equal to 22.0.The present application has excellent salt corrosion resistance and good yield strength, tensile strength and processing performance, and can meet the corrosion resistance requirements in a high-chlorine environment.

Description

Technical Field

[0001] This invention relates to the field of corrosion-resistant stainless steel preparation technology, and in particular to the processing technology of high-strength corrosion-resistant nitrogen-alloyed stainless steel strip. Background Technology

[0002] Stainless steel strips are characterized by high corrosion resistance, high tensile strength, and excellent processing performance, and are widely used in food processing, chemical industry, medical devices, marine engineering, and other fields. In the high-salt environment of marine engineering, even higher requirements are placed on the corrosion resistance of stainless steel. Conventional 304 stainless steel typically has an annual corrosion rate of ≤0.001 mm / year in fresh water at room temperature, but its pitting corrosion rate in flowing seawater increases sharply to 0.02-0.05 mm / year, failing to meet the corrosion resistance requirements in high-chlorine environments. While conventional 316 stainless steel exhibits better corrosion resistance in high-chlorine environments than 304 stainless steel, its pitting corrosion rate in flowing seawater is 0.01-0.03 mm / year, also failing to meet the corrosion resistance requirements in high-chlorine environments.

[0003] Furthermore, the yield strength of both 304 and 316 stainless steel is ≤320MPa, and their tensile strength is ≤680MPa. In summary, existing stainless steel strips suffer from deviations in mechanical properties and corrosion resistance, failing to meet the corrosion resistance requirements in high-chlorine environments. Therefore, this invention provides a high-strength, corrosion-resistant nitrogen-alloyed stainless steel strip and its processing technology. Summary of the Invention

[0004] To address the problem of existing stainless steel strips having a performance imbalance between mechanical properties and corrosion resistance, which limits their application range, this invention provides a processing technology for high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strips.

[0005] The high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip provided by this invention is achieved through the following technical solution:

[0006] The chemical composition of the high-strength corrosion-resistant nitrogen-alloyed stainless steel strip is as follows (by mass percentage): 0.25-0.45% N, 22-26% Cr, 5-10% Ni, 2-8% Mn, 1.8-2.4% Mo, 0.05-0.2% V, 0.05-0.2% Cu, 0.05-0.2% Ti, 0.01-0.04% Nb, ≤0.02% Al, ≤0.05% C, ≤1.0% Si, ≤0.030% P, ≤0.01% S, ≤0.005% O, with the balance being Fe and unavoidable impurities; the pitting corrosion resistance equivalent of the stainless steel strip = Cr% + 20*C% + 20*N% - 0.5*Mn% - 0.25*Ni% ≥ 22.0.

[0007] By limiting the pitting corrosion resistance equivalent of stainless steel strip, its good salt corrosion resistance can be guaranteed.

[0008] Preferably, the Cr equivalent in the stainless steel strip is Cr% + Mo% + 1.5*Si% + 0.5*Nb, and the Ni equivalent is Ni% + 30*C% + 0.5*Mn%. The Cr equivalent in the stainless steel strip is 24-30%, and the Ni equivalent is 8.5-13.0%.

[0009] By limiting the Cr and Ni equivalents, we can ensure that the pitting corrosion resistance equivalent is ≥22, thus guaranteeing good salt corrosion resistance. On the other hand, we can limit the content of austenite and ferrite in the stainless steel strip, and control the mechanical properties, processing properties and salt corrosion resistance of the prepared stainless steel by optimizing the content of austenite and ferrite.

[0010] Preferably, the Cr equivalent and Ni equivalent in the stainless steel strip satisfy the following relationship: Y = kX + B, where Y is the Ni equivalent; X is the Cr equivalent; k is 0.70 to 0.82; and B is -8.6 to -8.5.

[0011] By defining and experimentally verifying the Cr and Ni equivalents, a linear relationship between Cr and Ni equivalents at a ferrite content of 50±5% was established, enabling the preparation of stainless steel materials with good mechanical properties, processing performance, and salt corrosion resistance. Furthermore, while meeting the mechanical properties and salt corrosion resistance requirements of stainless steel materials, the amount of Cr and Ni can be reduced, thereby lowering overall production costs and enhancing the product's market competitiveness.

[0012] Preferably, the pitting corrosion resistance equivalent of the stainless steel strip is: Cr% + 20*C% + 20*N% - 0.5*Mn% - 0.25*Ni% ≥ 25.0.

[0013] More preferably, the chemical composition of a high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip is as follows (by mass percentage): 0.35-0.45% N, 22-26% Cr, 5-10% Ni, 4-6% Mn, 1.8-2.4% Mo, 0.1-0.2% V, 0.1-0.2% Cu, 0.1-0.2% Ti, 0.02-0.04% Nb, ≤0.02% Al, ≤0.03% C, ≤0.6% Si, ≤0.030% P, ≤0.005% S, ≤0.005% O, with the balance being Fe and unavoidable impurities.

[0014] The stainless steel strip in this invention has an annual corrosion rate of ≤0.01mm / year in flowing seawater; the stainless steel strip has a yield strength ≥500MPa, tensile strength ≥720MPa, elongation of 28-35%, and Vickers hardness of 245-280HV, which means it has excellent corrosion resistance and good yield strength, tensile strength, and processing performance, meeting the corrosion resistance requirements in high-chlorine environments.

[0015] The processing technology for the high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip provided by this invention is achieved through the following technical solutions:

[0016] A processing technology for high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip includes the following steps:

[0017] Step 1: Smelt stainless steel ingots according to the chemical composition formula of high-strength corrosion-resistant nitrogen-alloyed stainless steel strip.

[0018] Step 2: The stainless steel ingots from Step 1 are successively forged and hot-rolled to obtain rolled steel plates.

[0019] Step 3: Cut and grind the rolled steel plate from Step 2 to obtain a cold-rolled steel bar of a predetermined shape;

[0020] Step four: The steel strip to be cold rolled in step three undergoes solution treatment, cold rolling, strengthening precipitation treatment, pickling treatment, and leveling in sequence to obtain the finished high-strength corrosion-resistant nitrogen alloyed stainless steel strip.

[0021] The high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip processing technology of this invention is relatively simple. The production equipment used is all conventional steel strip production equipment, the technology is mature, it is easy to realize industrial manufacturing, reduce the overall production cost, and enhance product competitiveness.

[0022] Preferably, the solution treatment in step four is specifically operated as follows: heat the steel bar to 1050-1150℃ at a rate of 100-200℃ / h and hold for 2-4 hours, then use forced air cooling to cool it down to below 400℃ at a rate of ≥50℃ / min, and then allow it to cool naturally to room temperature to complete the solution treatment of the steel bar to be cold rolled.

[0023] Preferably, the enhanced precipitation treatment in step four is specifically operated as follows: after cold rolling, the temperature is raised to 580±5℃ at a rate of 100-200℃ / h and held for 120±5min to induce ε-Cu phase precipitation. Then, forced air cooling is used to lower the temperature to 450±5℃ at a rate of ≥50℃ / min and held for 30±5min to generate Nb(C,N) nanoclusters. Then, forced air cooling is used to lower the temperature to below 400℃ at a rate of ≥50℃ / min. The furnace is then opened and allowed to cool naturally to room temperature to complete the enhanced precipitation treatment.

[0024] More preferably, the enhanced precipitation treatment in step four is specifically operated as follows: after cold rolling, the temperature is raised to 580℃ at 100℃ / h and held for 120min to induce ε-Cu phase precipitation. Then, forced air cooling is used to lower the temperature to 450℃ at a rate of ≥50℃ / min and held for 30min to generate Nb(C,N) nanoclusters. Then, forced air cooling is used to lower the temperature to below 400℃ at a rate of ≥50℃ / min. The furnace is then opened and allowed to cool naturally to room temperature to complete the enhanced precipitation treatment.

[0025] The corrosion resistance and hardness of stainless steel strips can be further improved by adopting the above-mentioned enhanced precipitation treatment method.

[0026] In summary, the present invention has the following advantages:

[0027] 1. The high-strength corrosion-resistant nitrogen-alloyed stainless steel strip of the present invention has excellent salt corrosion resistance and good yield strength, tensile strength and processing performance, which can meet the corrosion resistance requirements in high chlorine environment.

[0028] 2. This invention ensures that the prepared stainless steel material has good salt corrosion resistance by optimizing the design of Cr equivalent and Ni equivalent. On the other hand, it limits the content of austenite and ferrite in the stainless steel strip. By optimizing the content of austenite and ferrite, the mechanical properties, processing properties and salt corrosion resistance of the prepared stainless steel can be controlled.

[0029] 3. The processing technology of the high-strength corrosion-resistant nitrogen-alloyed stainless steel strip in this invention is relatively simple. The production equipment used is conventional steel strip production equipment and the process is mature, which facilitates industrial manufacturing, reduces the overall production cost, and enhances product competitiveness.

[0030] 4. In this invention, by strengthening the precipitation process, the precipitation of ε-Cu phase is induced to generate Nb(C,N) nanoclusters, which can effectively improve the salt corrosion resistance and wear resistance of the prepared stainless steel material, and also help improve its mechanical properties. Detailed Implementation

[0031] To further understand the inventiveness and technical advancements of this invention, the preferred embodiments of this invention will be discussed in detail below with reference to examples and comparative examples.

[0032] Example: The chemical composition of high-strength corrosion-resistant nitrogen-alloyed stainless steel strip is as follows (mass percentage): 0.25-0.45% N, 22-26% Cr, 5-10% Ni, 2-8% Mn, 1.8-2.4% Mo, 0.05-0.2% V, 0.05-0.2% Cu, 0.05-0.2% Ti, 0.01-0.04% Nb, ≤0.02% Al, ≤0.05% C, ≤1.0% Si, ≤0.030% P, ≤0.01% S, ≤0.005% O, with the balance being Fe and unavoidable impurities.

[0033] To ensure the corrosion resistance of the stainless steel strip, the pitting corrosion resistance equivalent = Cr% + 20*C% + 20*N% - 0.5*Mn% - 0.25*Ni% ≥ 22.0. Preferably, the pitting corrosion resistance equivalent design requirement is ≥ 25.0.

[0034] In high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip, the Cr equivalent is calculated as Cr% + Mo% + 1.5*Si% + 0.5*Nb%, and the Ni equivalent is calculated as Ni% + 30*C% + 0.5*Mn%. The Cr equivalent is 24-30%, and the Ni equivalent is 8.5-13.0%. The Cr equivalent and Ni equivalent satisfy the following relationship: Y = kX + B, where Y is the Ni equivalent, X is the Cr equivalent, k is 0.70-0.82, and B is -8.6 to -8.5.

[0035] The preferred formulation for high-strength, corrosion-resistant nitrogen-alloyed stainless steel strip is as follows: 0.35-0.45% N, 22-26% Cr, 5-10% Ni, 4-6% Mn, 1.8-2.4% Mo, 0.1-0.2% V, 0.1-0.2% Cu, 0.1-0.2% Ti, 0.02-0.04% Nb, ≤0.02% Al, ≤0.03% C, ≤0.6% Si, ≤0.030% P, ≤0.005% S, ≤0.005% O, with the balance being Fe and unavoidable impurities. Pitting corrosion resistance equivalent = Cr% + 20*C% + 20*N% - 0.5*Mn% - 0.25*Ni% ≥ 25.

[0036] A processing technology for high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip includes the following steps:

[0037] Step 1: Smelt stainless steel ingots according to the chemical composition formula of high-strength corrosion-resistant nitrogen-alloyed stainless steel strip.

[0038] Step 2: The stainless steel ingots from Step 1 are successively forged and hot-rolled to obtain rolled steel plates.

[0039] The forging process of stainless steel ingots is as follows: the stainless steel ingots are heated to 1050-1150℃ for homogenization treatment for 4-8 hours, and then the homogenized stainless steel ingots are subjected to high-pressure fast forging treatment. The initial forging temperature is 1150℃, the final forging temperature is ≥980℃, and the forging ratio is 6-8. After the forging process is completed, the forged billet is obtained.

[0040] The hot rolling process for forged billets is as follows:

[0041] ① Hot rough rolling: The forged billet is hot-rolled in eight passes to obtain a rough rolled steel plate. The initial rolling temperature is 1150℃, the final forging temperature is ≥980℃, the deformation of a single pass is 8-15%, the total deformation of hot rough rolling is 55-75%, and the thickness of the rough rolled steel plate is 0.30-0.45 times the thickness of the forged billet. Specifically, the deformation of the eight passes of hot rough rolling are ζ1, ζ2, ζ3, ζ4, ζ5, ζ6, ζ7, and ζ8, and the thickness of the forged billet is b0. Then the thickness of the rough rolled steel plate is b1 = b0*(1-ζ1)*(1-ζ2)*(1-ζ3)*(1-ζ4)*(1-ζ6)*(1-ζ7)*(1-ζ8).

[0042] ② Hot finishing rolling: At least ten hot finishing rolling passes are performed on the rough-rolled steel plate to obtain a finished steel plate. The initial rolling temperature is 1180℃, and the final forging temperature is ≥980℃. The deformation per pass is 2-6%, and the thickness of the resulting finished steel plate is 0.15-0.25 times the thickness of the forged billet. Specifically, the number of hot finishing passes is n, and the deformation per n passes is ξ1, ξ2, ..., ξ. n Then the thickness of the precision-rolled steel plate, b2 = b1*(1-ξ1)*(1-ξ2)*……*(1-ξ n That is, by controlling the deformation amount of hot rough rolling and hot fine rolling, the thickness of fine rolled steel plate can be controlled to meet the final thickness design requirements of stainless steel strip.

[0043] Step 3: Cut and grind the rolled steel plate from Step 2 to obtain a cold-rolled steel bar of a predetermined shape;

[0044] Step four: The steel strip to be cold rolled in step three undergoes solution treatment, cold rolling, strengthening precipitation treatment, pickling treatment, and leveling in sequence to obtain a high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip.

[0045] The solution treatment is as follows: heat the furnace at 100-200℃ / h to 1050-1150℃ and hold for 2-4 hours. Then, use forced air cooling to cool the furnace at a rate of ≥50℃ / min to below 400℃. After cooling, allow the furnace to cool naturally to room temperature.

[0046] After solution treatment, the steel strip to be cold-rolled is subjected to cold rolling, specifically as follows: the steel strip to be cold-rolled is subjected to three passes of large deformation cold rough rolling, with a total deformation of 80-90%, followed by six passes of small deformation cold precision rolling, with a total deformation of 20-30%. The thickness of the resulting cold-rolled stainless steel strip is equal to 0.05-0.10 times the thickness of the steel strip to be cold-rolled.

[0047] The specific precipitation enhancement treatment is as follows: After cold rolling, the temperature is raised to 580±5℃ at a rate of 100-200℃ / h and held for 120±5min to induce ε-Cu phase precipitation. Then, forced air cooling is used to lower the temperature to 450±5℃ at a rate of ≥50℃ / min and held for 30±5min to generate Nb(C,N) nanoclusters. Then, forced air cooling is used to lower the temperature to below 400℃ at a rate of ≥50℃ / min. The furnace is then opened and allowed to cool naturally to room temperature.

[0048] The pickling process is as follows: the medium in the neutral salt electrolysis section is Na2SO4 with a concentration of 180±20g / L and a current of 4000-4500A; the medium in the mixed acid pickling section is H2SO4 and HF, with H2SO4 concentration of 60±5g / L and HF concentration of 30g±5 / L; after the stainless steel strip completes the pickling process, it undergoes online leveling treatment, with elongation controlled at 0.3-0.7%, rolling force of 1100-1350KN, and leveling tension of 150-160KN to obtain the finished high-strength corrosion-resistant nitrogen alloyed stainless steel strip.

[0049] Example 1: The processing technology of high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip includes the following steps:

[0050] Step 1: Weigh out 3N electrolytic iron, pig iron, iron-silicon Fe15Si alloy, iron-copper master alloy CuFe10, 4N pure chromium, 4N pure nickel, and titanium-iron alloy FeTi40 according to the formula of 0.40% Si, 22% Cr, 8% Ni, 5% Mn, and balance Fe. Add these ingredients to an electric furnace for smelting. The temperature of the molten steel in the electric furnace is 1680℃. After melting and dephosphorizing the slag, tap the molten steel when P ≤ 0.015% at a temperature of 1580℃. The elemental composition of the resulting molten steel is as follows: 0.089% C, 0.015% P, 0.009% S, 0.40% Si, 21.98% Cr, 7. 99% Ni, 0.10% Cu, 0.10% Ti, balance Fe; lime powder is added for complete slag removal, and a reducing slag (CaF2-Al2O3-CaO ternary slag system: CaF2-Al2O3-CaO mass ratio 14:3:3) is re-formed in the ladle. Nitrogen is top-blown, and desulfurization is carried out under nitrogen atmosphere to achieve a sulfur content of 0.003%. The molten steel is then decarburized in an AOD furnace, and aluminum granules are added for deoxidation. The AOD smelting temperature is 1650℃. The C content in the molten steel is adjusted to 0.03% and the oxygen content to 30ppm. Iron-vanadium alloy FeV50 and iron-niobium alloy Fe65Nb are added, and the smelting temperature is 1... At 650℃, the V content in the molten steel was adjusted to 0.10% and the Nb content to 0.02%. Then, LF refining was performed at 1580℃, adding high-purity manganese and molybdenum particles (99.95% purity). The Mn content in the molten steel was adjusted to 5.00% and the Mo content to 2.00%. Finally, a nitrogen-argon mixture was blown into the bottom of the ladle at a nitrogen-argon volume ratio of 1:2, a flow rate of 25 L / min, and a soft-blowing time of 45 min, adjusting the N content in the molten steel to 0.35%. Subsequently, continuous casting was performed to obtain a billet, with the molten steel temperature adjusted to 1550℃ and the billet casting speed at 1 m / min. n, Crystallizer vibration: amplitude 5mm, frequency 120 times / min, passing through the foot roller section (cooling water flow rate of 0.60L / kg molten steel), the first sector section (cooling water flow rate of 0.45L / kg molten steel), the second sector section (cooling water flow rate of 0.30L / kg molten steel), and the third sector section (cooling water flow rate of 0.25L / kg molten steel) for cooling. The resulting columnar steel billet is cut by flame cutting. The surface of the cut steel block is ground to remove defects. 3mm is ground off the upper surface and 1mm is ground off the lower surface. Then, the surface oxides are removed by pickling with 0.1mol / L sulfuric acid aqueous solution to obtain the finished steel ingot.

[0051] Step Two: The steel ingots obtained in Step One are forged and hot-rolled to obtain rolled steel plates. Specifically, the steel ingots prepared in Step One are heated to 1150℃ for homogenization treatment for 6 hours. Then, the homogenized steel ingots are subjected to high-pressure rapid forging treatment, with an initial forging temperature of 1150℃ and a final forging temperature of 980℃, and a forging ratio of 8 to obtain forged billets. The obtained forged billets are then subjected to eight passes of hot rough rolling to obtain rough-rolled steel plates, with an initial rolling temperature of 1150℃ and a final forging temperature of 980℃. The deformation amounts of the eight hot rough rolling passes are 15%, 15%, and 15%, respectively. 15%, 10%, 10%, 10%, 8%, the total deformation of hot rough rolling is 63%, and the thickness of the rough rolled steel plate is equal to 0.37 times the thickness of the forged billet plate; the rough rolled steel plate is subjected to twelve passes of hot fine rolling to obtain a fine rolled steel plate, with an initial rolling temperature of 1180℃ and a final forging temperature of 980℃. The deformation amounts of the twelve passes of hot fine rolling are 6%, 6%, 6%, 6%, 5%, 5%, 5%, 5%, 4%, 4%, 4%, 4%, 4%, and the thickness of the resulting fine rolled steel plate is equal to 0.20 times the thickness of the forged billet plate;

[0052] Step 3: Cut the rolled steel plate to obtain steel bars with a width-to-height ratio of 3:1, and grind off the burrs to obtain steel bars to be cold rolled;

[0053] Step four: The steel strip to be cold rolled in step three undergoes solution treatment, cold rolling, strengthening precipitation treatment, pickling treatment, and leveling in sequence to obtain a high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip.

[0054] Specifically, the solution treatment of the steel bar to be cold rolled involves heating to 1120℃ at 100℃ / h and holding for 4 hours, then cooling to 380℃ at a rate of 60℃ / min using forced air cooling, and finally allowing it to cool naturally to room temperature to obtain the steel bar to be cold rolled.

[0055] After solution treatment, the steel strip to be cold-rolled undergoes cold rolling as follows: First, the steel strip is subjected to four passes of large deformation cold rough rolling, with deformation amounts of 45%, 45%, 40%, and 40% respectively, resulting in a total deformation of 89.1%. The thickness of the sheet after the four passes of large deformation cold rough rolling is 0.109 times the thickness of the steel strip to be cold-rolled. Subsequently, six passes of small deformation cold precision rolling are performed, with deformation amounts of 8%, 6%, 6%, 4%, 4%, and 2% respectively, yielding a cold-rolled stainless steel strip. The thickness of the resulting cold-rolled stainless steel strip is equal to 0.080 times the thickness of the steel strip to be cold-rolled.

[0056] The specific precipitation enhancement treatment is as follows: After cold rolling, the temperature is raised to 580℃ at 100℃ / h and held for 120min to induce ε-Cu phase precipitation. Then, forced air cooling is used to lower the temperature to 450℃ at a rate of 50℃ / min and hold for 30min to generate Nb(C,N) nanoclusters. Then, forced air cooling is used to lower the temperature to 390℃ at a rate of 60℃ / min. The furnace is then opened and allowed to cool naturally to room temperature.

[0057] The pickling process is as follows: A continuous pickling process of neutral salt electrolysis followed by mixed acid pickling is used to pickle the stainless steel strip. The medium in the neutral salt electrolysis section is Na2SO4 with a concentration of 180 g / L and a current of 4500 A. The medium in the mixed acid pickling section is H2SO4 and HF, with H2SO4 concentration of 60 g / L and HF concentration of 30 g / L. After pickling, the stainless steel strip undergoes online leveling, with elongation controlled at 0.4%, rolling force controlled at 1250 KN, and leveling tension at 155 KN to obtain a high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip.

[0058] The final high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip has the following alloy element composition: 0.35% N, 0.03% C, 0.40% Si, 0.015% P, 0.003% S, 0.003% O, 21.98% Cr, 7.99% Ni, 5.0% Mn, 2.0% Mo, 0.10% V, 0.10% Cu, 0.10% Ti, 0.02% Nb, 0.016% Al, with the balance being Fe and unavoidable impurities. The Md30 of the high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip is calculated as follows: Md30 = -241.6. The Cr equivalent in the stainless steel strip is 24.59, the Ni equivalent is 11.39, and the pitting corrosion resistance equivalent is 25.08. The Cr equivalent and Ni equivalent satisfy the following relationship: Y = kX - 8.6, where Y is the Ni equivalent, X is the Cr equivalent, and k is 0.813.

[0059] The difference between Example 2 and Example 1 is as follows: Step 1 of the processing technology for high-strength corrosion-resistant nitrogen-alloyed stainless steel strip: Weigh 3N electrolytic iron, pig iron, iron-silicon Fe15Si alloy, iron-copper master alloy CuFe10, 4N pure chromium, 4N pure nickel, and titanium-iron alloy FeTi40 according to the formula of 0.40% Si, 22% Cr, 6.7% Ni, 5% Mn, and the balance Fe. Add these ingredients to an electric furnace for smelting. The temperature of the molten steel in the electric furnace is 1680℃. After melting and cleaning, dephosphorize the slag. After P ≤ 0.015%, tap the molten steel at a temperature of 1580℃. The elemental composition of the obtained molten steel is as follows: 0.089% C, 0.015% P, 0.0 The molten iron contains 0.09% S, 0.40% Si, 21.98% Cr, 6.69% Ni, 0.10% Cu, 0.10% Ti, and the balance Fe. Lime powder is added for complete slag removal, and a reducing slag (CaF2-Al2O3-CaO ternary slag system: CaF2-Al2O3-CaO mass ratio 14:3:3) is re-formed in the ladle. Nitrogen is top-blown, and desulfurization is carried out under a nitrogen atmosphere with stirring to achieve a sulfur content of 0.003%. The molten iron is then decarburized in an AOD furnace, and aluminum granules are added for deoxidation. The AOD smelting temperature is 1650℃. The C content in the molten steel is adjusted to 0.03% and the oxygen content to 30ppm. Iron-vanadium alloy FeV50 is added. The Fe65Nb alloy was smelted at 1650℃, with the V content in the molten steel adjusted to 0.10% and the Nb content to 0.02%. Then, LF refining was performed at 1580℃, adding 99.95% pure manganese and molybdenum particles to adjust the Mn content to 5.00% and the Mo content to 2.00%. Finally, a nitrogen-argon mixture was blown into the bottom of the ladle at a nitrogen-argon volume ratio of 1:2, a flow rate of 25 L / min, and a soft-blowing time of 45 min, adjusting the N content in the molten steel to 0.35%. The steel was then continuously cast to obtain a billet at 1550℃. The billet pulling speed is 1 m / min, and the crystallizer vibration is 5 mm amplitude and 120 times / min. The billet is cooled through the foot roll section (cooling water flow rate of 0.60 L / kg molten steel), the first sector section (cooling water flow rate of 0.45 L / kg molten steel), the second sector section (cooling water flow rate of 0.30 L / kg molten steel), and the third sector section (cooling water flow rate of 0.25 L / kg molten steel). The resulting columnar billet is then flame-cut. The surface of the cut billet is ground to remove defects, with 3 mm of the upper surface and 1 mm of the lower surface ground off. The surface oxides are removed by pickling with a 0.1 mol / L sulfuric acid aqueous solution to obtain the finished steel ingot.

[0060] The final high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip has the following alloy element composition: 0.35% N, 0.03% C, 0.40% Si, 0.015% P, 0.003% S, 0.003% O, 21.98% Cr, 6.69% Ni, 5.0% Mn, 2.0% Mo, 0.10% V, 0.10% Cu, 0.10% Ti, 0.02% Nb, 0.016% Al, with the balance being Fe and unavoidable impurities. The Md30 of the high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip is calculated as follows: Md30 = -203.9. The Cr equivalent in the stainless steel strip is 24.59, the Ni equivalent is 10.09, and the pitting corrosion resistance equivalent is 25.41. The Cr equivalent and Ni equivalent satisfy the following relationship: Y = kX - 8.6, where Y is the Ni equivalent, X is the Cr equivalent, and k is 0.760.

[0061] The difference between Example 3 and Example 1 is as follows: Step 1 of the processing technology for high-strength corrosion-resistant nitrogen-alloyed stainless steel strip: Weigh 3N electrolytic iron, pig iron, iron-silicon Fe15Si alloy, iron-copper intermediate alloy CuFe10, 4N pure chromium, 4N pure nickel, and titanium-iron alloy FeTi40 according to the formula of 0.40% Si, 22% Cr, 5.65% Ni, 5% Mn, and the balance Fe, and put them into an electric furnace for smelting. The temperature of the molten steel in the electric furnace is 1680℃. After melting and cleaning, the slag is dephosphorized. After P≤0.015%, the molten steel is tapped at a temperature of 1580℃. The elemental composition of the obtained molten steel is as follows: 0.089% C, 0.015% P, 0. The molten iron contains 0.009% S, 0.40% Si, 21.98% Cr, 5.64% Ni, 0.10% Cu, 0.10% Ti, and the balance Fe. Lime powder is added for complete slag removal, and a reducing slag (CaF2-Al2O3-CaO ternary slag system: CaF2-Al2O3-CaO mass ratio 14:3:3) is re-formed in the ladle. Nitrogen is top-blown, and desulfurization is carried out under a nitrogen atmosphere with stirring to achieve a sulfur content of 0.003%. The molten iron is then decarburized in an AOD furnace, and aluminum granules are added for deoxidation. The AOD smelting temperature is 1650℃. The C content in the molten steel is adjusted to 0.03% and the oxygen content to 30ppm. Iron-vanadium alloy FeV50 is added. The Fe65Nb alloy was smelted at 1650℃, with the V content in the molten steel adjusted to 0.10% and the Nb content to 0.02%. Then, LF refining was performed at 1580℃, adding 99.95% pure manganese and molybdenum particles to adjust the Mn content to 5.00% and the Mo content to 2.00%. Finally, a nitrogen-argon mixture was blown into the bottom of the ladle at a nitrogen-argon volume ratio of 1:2, a flow rate of 25 L / min, and a soft-blowing time of 45 min, adjusting the N content in the molten steel to 0.35%. The steel was then continuously cast to obtain a billet at 1550℃. The billet pulling speed is 1 m / min, and the crystallizer vibration is 5 mm amplitude and 120 times / min. The billet is cooled through the foot roll section (cooling water flow rate of 0.60 L / kg molten steel), the first sector section (cooling water flow rate of 0.45 L / kg molten steel), the second sector section (cooling water flow rate of 0.30 L / kg molten steel), and the third sector section (cooling water flow rate of 0.25 L / kg molten steel). The resulting columnar billet is then flame-cut. The surface of the cut billet is ground to remove defects, with 3 mm of the upper surface and 1 mm of the lower surface ground off. The surface oxides are removed by pickling with a 0.1 mol / L sulfuric acid aqueous solution to obtain the finished steel ingot.

[0062] The final high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip has the following alloy element composition: 0.35% N, 0.03% C, 0.40% Si, 0.015% P, 0.003% S, 0.003% O, 21.98% Cr, 5.64% Ni, 5.0% Mn, 2.0% Mo, 0.10% V, 0.10% Cu, 0.10% Ti, 0.02% Nb, 0.016% Al, with the balance being Fe and unavoidable impurities. The Md30 of the high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip is calculated as follows: Md30 = -173.46. The Cr equivalent in the stainless steel strip is 24.59, the Ni equivalent is 9.04, and the pitting corrosion resistance equivalent is 25.67. The Cr equivalent and Ni equivalent satisfy the following relationship: Y = kX - 8.6, where Y is the Ni equivalent, X is the Cr equivalent, and k is 0.717.

[0063] The difference between Example 4 and Example 1 is as follows: Step 1 of the processing technology for high-strength corrosion-resistant nitrogen-alloyed stainless steel strip: Step 1 of the processing technology for high-strength corrosion-resistant nitrogen-alloyed stainless steel strip: Weigh 3N electrolytic iron, pig iron, iron-silicon Fe15Si alloy, iron-copper intermediate alloy CuFe10, 4N pure chromium, 4N pure nickel, and titanium-iron alloy FeTi40 according to the formula of 0.40% Si, 22% Cr, 5.26% Ni, 5% Mn, and the balance being Fe. The materials are then fed into an electric furnace for smelting. The temperature of the molten steel in the electric furnace is 1680℃. After melting and cleaning, the slag is dephosphorized. After P ≤ 0.015%, the molten steel is tapped at a temperature of 1580℃. The elemental composition of the obtained molten steel is as follows: 0.08 The molten iron contains 9% C, 0.015% P, 0.009% S, 0.40% Si, 21.98% Cr, 5.25% Ni, 0.10% Cu, 0.10% Ti, and the balance is Fe. Lime powder is added for complete slag removal. A reducing slag (CaF2-Al2O3-CaO ternary slag system: CaF2-Al2O3-CaO mass ratio 14:3:3) is then formed in the ladle. Nitrogen is top-blown, and desulfurization is performed under a nitrogen atmosphere with stirring to achieve a sulfur content of 0.003%. The molten iron is then decarburized in an AOD furnace, and aluminum granules are added for deoxidation. The AOD smelting temperature is 1650℃, and the C content in the molten steel is adjusted to 0.03% and the oxygen content to 30ppm. Iron-vanadium alloy FeV50 and iron-niobium alloy Fe65Nb were added, and the smelting temperature was 1650℃. The V content in the molten steel was adjusted to 0.10% and the Nb content to 0.02%. Then, LF refining was performed, and the temperature was adjusted to 1580℃. High-purity manganese particles and high-purity molybdenum particles with a purity of 99.95% were added, and the Mn content in the molten steel was adjusted to 5.00% and the Mo content to 2.00%. Finally, a nitrogen-argon mixture was blown into the bottom of the ladle. The volume ratio of nitrogen to argon in the nitrogen-argon mixture was 1:2, the flow rate of the nitrogen-argon mixture was 25 L / min, and the soft blowing time of the nitrogen-argon mixture was 45 min, adjusting the N content in the molten steel to 0.35%. Subsequently, continuous casting was performed to obtain a steel billet, and the temperature of the molten steel was adjusted to... At 1550℃, the billet pulling speed is 1m / min, and the crystallizer vibration is 5mm amplitude and 120 times / min. The billet is cooled through the foot roll section (cooling water flow rate of 0.60L / kg molten steel), the first sector section (cooling water flow rate of 0.45L / kg molten steel), the second sector section (cooling water flow rate of 0.30L / kg molten steel), and the third sector section (cooling water flow rate of 0.25L / kg molten steel). The resulting columnar billet is then flame-cut. The surface of the cut billet is ground to remove defects, with 3mm of the upper surface and 1mm of the lower surface ground off. The surface oxides are removed by pickling with a 0.1mol / L sulfuric acid aqueous solution to obtain the finished steel ingot.

[0064] The final high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip has the following alloy element composition: 0.35% N, 0.03% C, 0.40% Si, 0.015% P, 0.003% S, 0.003% O, 21.98% Cr, 5.25% Ni, 5.0% Mn, 2.0% Mo, 0.10% V, 0.10% Cu, 0.10% Ti, 0.02% Nb, 0.016% Al, with the balance being Fe and unavoidable impurities. The Md30 of the high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip is calculated as follows: Md30 = -162.15. The Cr equivalent in the stainless steel strip is 24.59, the Ni equivalent is 8.65, and the pitting corrosion resistance equivalent is 25.77. The Cr equivalent and Ni equivalent satisfy the following relationship: Y = kX - 8.6, where Y is the Ni equivalent, X is the Cr equivalent, and k is 0.702.

[0065] The difference between Example 5 and Example 3 is as follows: Step 1 of the processing technology for high-strength corrosion-resistant nitrogen-alloyed stainless steel strip: Weigh 3N electrolytic iron, pig iron, iron-silicon Fe15Si alloy, iron-copper intermediate alloy CuFe10, 4N pure chromium, 4N pure nickel, and titanium-iron alloy FeTi40 according to the formula of 0.40% Si, 22% Cr, 5.65% Ni, 5% Mn, and the balance Fe, and put them into an electric furnace for smelting. The temperature of the molten steel in the electric furnace is 1680℃. After melting and cleaning, the slag is dephosphorized. After P≤0.015%, the molten steel is tapped at a temperature of 1580℃. The elemental composition of the obtained molten steel is as follows: 0.089% C, 0.015% P, 0. The molten iron contains 0.009% S, 0.40% Si, 21.98% Cr, 5.64% Ni, 0.10% Cu, 0.10% Ti, and the balance Fe. Lime powder is added for complete slag removal, and a reducing slag (CaF2-Al2O3-CaO ternary slag system: CaF2-Al2O3-CaO mass ratio 14:3:3) is re-formed in the ladle. Nitrogen is top-blown, and desulfurization is carried out under a nitrogen atmosphere with stirring to achieve a sulfur content of 0.003%. The molten iron is then decarburized in an AOD furnace, and aluminum granules are added for deoxidation. The AOD smelting temperature is 1650℃. The C content in the molten steel is adjusted to 0.03% and the oxygen content to 30ppm. Iron-vanadium alloy FeV50 is added. The Fe65Nb alloy was smelted at 1650℃, with the V content in the molten steel adjusted to 0.10% and the Nb content to 0.02%. Then, LF refining was performed at 1580℃, adding 99.95% pure manganese and molybdenum particles to adjust the Mn content to 5.00% and the Mo content to 2.00%. Finally, a nitrogen-argon mixture was blown into the bottom of the ladle at a nitrogen-argon volume ratio of 1:2, a flow rate of 25 L / min, and a soft-blowing time of 30 min, adjusting the N content in the molten steel to 0.25%. The steel was then continuously cast to obtain a billet, with the molten steel temperature adjusted to 1550℃. The billet pulling speed is 1 m / min, and the crystallizer vibration is 5 mm amplitude and 120 times / min. The billet is cooled through the foot roll section (cooling water flow rate of 0.60 L / kg molten steel), the first sector section (cooling water flow rate of 0.45 L / kg molten steel), the second sector section (cooling water flow rate of 0.30 L / kg molten steel), and the third sector section (cooling water flow rate of 0.25 L / kg molten steel). The resulting columnar billet is then flame-cut. The surface of the cut billet is ground to remove defects, with 3 mm of the upper surface and 1 mm of the lower surface ground off. The surface oxides are removed by pickling with a 0.1 mol / L sulfuric acid aqueous solution to obtain the finished steel ingot.

[0066] The final high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip has the following alloy element composition: 0.25% N, 0.03% C, 0.40% Si, 0.015% P, 0.003% S, 0.003% O, 21.98% Cr, 5.64% Ni, 5.0% Mn, 2.0% Mo, 0.10% V, 0.10% Cu, 0.10% Ti, 0.02% Nb, 0.016% Al, with the balance being Fe and unavoidable impurities. The Md30 of the high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip is calculated as follows: Md30 = -127.26. The Cr equivalent in the stainless steel strip is 24.59, the Ni equivalent is 9.04, and the pitting corrosion resistance equivalent is 23.67.

[0067] The difference between Example 6 and Example 3 is as follows: Step 1 of the processing technology for high-strength corrosion-resistant nitrogen-alloyed stainless steel strip: Weigh 3N electrolytic iron, pig iron, iron-silicon Fe15Si alloy, iron-copper intermediate alloy CuFe10, 4N pure chromium, 4N pure nickel, and titanium-iron alloy FeTi40 according to the formula of 0.40% Si, 22% Cr, 5.65% Ni, 5% Mn, and the balance Fe, and put them into an electric furnace for smelting. The temperature of the molten steel in the electric furnace is 1680℃. After melting and cleaning, the slag is dephosphorized. After P≤0.015%, the molten steel is tapped at a temperature of 1580℃. The elemental composition of the obtained molten steel is as follows: 0.089% C, 0.015% P, 0. The molten iron contains 0.009% S, 0.40% Si, 21.98% Cr, 5.64% Ni, 0.10% Cu, 0.10% Ti, and the balance Fe. Lime powder is added for complete slag removal, and a reducing slag (CaF2-Al2O3-CaO ternary slag system: CaF2-Al2O3-CaO mass ratio 14:3:3) is re-formed in the ladle. Nitrogen is top-blown, and desulfurization is carried out under a nitrogen atmosphere with stirring to achieve a sulfur content of 0.003%. The molten iron is then decarburized in an AOD furnace, and aluminum granules are added for deoxidation. The AOD smelting temperature is 1650℃. The C content in the molten steel is adjusted to 0.03% and the oxygen content to 30ppm. Iron-vanadium alloy FeV50 is added. The Fe65Nb alloy was smelted at 1650℃, with the V content in the molten steel adjusted to 0.10% and the Nb content to 0.02%. Then, LF refining was performed at 1580℃, adding 99.95% pure manganese and molybdenum particles to adjust the Mn content to 5.00% and the Mo content to 2.00%. Finally, a nitrogen-argon mixture was blown into the bottom of the ladle at a nitrogen-argon volume ratio of 1:2, a flow rate of 25 L / min, and a soft-blowing time of 35 min, adjusting the N content in the molten steel to 0.30%. The steel was then continuously cast to obtain a billet, with the molten steel temperature adjusted to 1550℃. The billet pulling speed is 1 m / min, and the crystallizer vibration is 5 mm amplitude and 120 times / min. The billet is cooled through the foot roll section (cooling water flow rate of 0.60 L / kg molten steel), the first sector section (cooling water flow rate of 0.45 L / kg molten steel), the second sector section (cooling water flow rate of 0.30 L / kg molten steel), and the third sector section (cooling water flow rate of 0.25 L / kg molten steel). The resulting columnar billet is then flame-cut. The surface of the cut billet is ground to remove defects, with 3 mm of the upper surface and 1 mm of the lower surface ground off. The surface oxides are removed by pickling with a 0.1 mol / L sulfuric acid aqueous solution to obtain the finished steel ingot.

[0068] The final high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip has the following alloy element composition: 0.30% N, 0.03% C, 0.40% Si, 0.015% P, 0.003% S, 0.003% O, 21.98% Cr, 5.64% Ni, 5.0% Mn, 2.0% Mo, 0.10% V, 0.10% Cu, 0.10% Ti, 0.02% Nb, 0.016% Al, with the balance being Fe and unavoidable impurities. The Md30 of the high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip is calculated as follows: Md30 = -150.36. The Cr equivalent in the stainless steel strip is 24.59, the Ni equivalent is 9.04, and the pitting corrosion resistance equivalent is 24.67.

[0069] The difference between Example 7 and Example 3 is as follows: Step 1 of the processing technology for high-strength corrosion-resistant nitrogen-alloyed stainless steel strip: Weigh 3N electrolytic iron, pig iron, iron-silicon Fe15Si alloy, iron-copper intermediate alloy CuFe10, 4N pure chromium, 4N pure nickel, and titanium-iron alloy FeTi40 according to the formula of 0.40% Si, 22% Cr, 5.65% Ni, 5% Mn, and the balance Fe, and put them into an electric furnace for smelting. The temperature of the molten steel in the electric furnace is 1680℃. After melting and cleaning, the slag is dephosphorized. After P≤0.015%, the molten steel is tapped at a temperature of 1580℃. The elemental composition of the obtained molten steel is as follows: 0.089% C, 0.015% P, 0. The molten iron contains 0.009% S, 0.40% Si, 21.98% Cr, 5.64% Ni, 0.10% Cu, 0.10% Ti, and the balance Fe. Lime powder is added for complete slag removal, and a reducing slag (CaF2-Al2O3-CaO ternary slag system: CaF2-Al2O3-CaO mass ratio 14:3:3) is re-formed in the ladle. Nitrogen is top-blown, and desulfurization is carried out under a nitrogen atmosphere with stirring to achieve a sulfur content of 0.003%. The molten iron is then decarburized in an AOD furnace, and aluminum granules are added for deoxidation. The AOD smelting temperature is 1650℃. The C content in the molten steel is adjusted to 0.03% and the oxygen content to 30ppm. Iron-vanadium alloy FeV50 is added. The Fe65Nb alloy was smelted at 1650℃, with the V content in the molten steel adjusted to 0.10% and the Nb content to 0.02%. Then, LF refining was performed at 1580℃, adding 99.95% pure manganese and molybdenum particles to adjust the Mn content to 5.00% and the Mo content to 2.00%. Finally, a nitrogen-argon mixture was blown into the bottom of the ladle at a nitrogen-argon volume ratio of 1:2, a flow rate of 25 L / min, and a soft-blowing time of 50 min, adjusting the N content in the molten steel to 0.40%. The steel was then continuously cast to obtain a billet, with the molten steel temperature adjusted to 1550℃. The billet pulling speed is 1 m / min, and the crystallizer vibration is 5 mm amplitude and 120 times / min. The billet is cooled through the foot roll section (cooling water flow rate of 0.60 L / kg molten steel), the first sector section (cooling water flow rate of 0.45 L / kg molten steel), the second sector section (cooling water flow rate of 0.30 L / kg molten steel), and the third sector section (cooling water flow rate of 0.25 L / kg molten steel). The resulting columnar billet is then flame-cut. The surface of the cut billet is ground to remove defects, with 3 mm of the upper surface and 1 mm of the lower surface ground off. The surface oxides are removed by pickling with a 0.1 mol / L sulfuric acid aqueous solution to obtain the finished steel ingot.

[0070] The final high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip has the following alloy element composition: 0.40% N, 0.03% C, 0.40% Si, 0.015% P, 0.003% S, 0.003% O, 21.98% Cr, 5.64% Ni, 5.0% Mn, 2.0% Mo, 0.10% V, 0.10% Cu, 0.10% Ti, 0.02% Nb, 0.016% Al, with the balance being Fe and unavoidable impurities. The Md30 of the high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip is calculated as follows: Md30 = -196.56. The Cr equivalent in the stainless steel strip is 24.59, the Ni equivalent is 9.04, and the pitting corrosion resistance equivalent is 26.67.

[0071] The difference between Example 8 and Example 3 is as follows: Step 1 of the processing technology for high-strength corrosion-resistant nitrogen-alloyed stainless steel strip: Weigh 3N electrolytic iron, pig iron, iron-silicon Fe15Si alloy, iron-copper intermediate alloy CuFe10, 4N pure chromium, 4N pure nickel, and titanium-iron alloy FeTi40 according to the formula of 0.40% Si, 22% Cr, 5.65% Ni, 5% Mn, and the balance Fe, and put them into an electric furnace for smelting. The temperature of the molten steel in the electric furnace is 1680℃. After melting and cleaning, the slag is dephosphorized. After P≤0.015%, the molten steel is tapped at a temperature of 1580℃. The elemental composition of the obtained molten steel is as follows: 0.089% C, 0.015% P, 0. The molten iron contains 0.009% S, 0.40% Si, 21.98% Cr, 5.64% Ni, 0.10% Cu, 0.10% Ti, and the balance Fe. Lime powder is added for complete slag removal, and a reducing slag (CaF2-Al2O3-CaO ternary slag system: CaF2-Al2O3-CaO mass ratio 14:3:3) is re-formed in the ladle. Nitrogen is top-blown, and desulfurization is carried out under a nitrogen atmosphere with stirring to achieve a sulfur content of 0.003%. The molten iron is then decarburized in an AOD furnace, and aluminum granules are added for deoxidation. The AOD smelting temperature is 1650℃. The C content in the molten steel is adjusted to 0.03% and the oxygen content to 30ppm. Iron-vanadium alloy FeV50 is added. The Fe65Nb alloy was smelted at 1650℃, with the V content in the molten steel adjusted to 0.10% and the Nb content to 0.02%. Then, LF refining was performed at 1580℃, adding 99.95% pure manganese and molybdenum particles to adjust the Mn content to 5.00% and the Mo content to 2.00%. Finally, a nitrogen-argon mixture was blown into the bottom of the ladle at a nitrogen-argon volume ratio of 1:2, a flow rate of 25 L / min, and a soft-blowing time of 60 min, adjusting the N content in the molten steel to 0.45%. The steel was then continuously cast to obtain a billet, with the molten steel temperature adjusted to 1550℃. The billet pulling speed is 1 m / min, and the crystallizer vibration is 5 mm amplitude and 120 times / min. The billet is cooled through the foot roll section (cooling water flow rate of 0.60 L / kg molten steel), the first sector section (cooling water flow rate of 0.45 L / kg molten steel), the second sector section (cooling water flow rate of 0.30 L / kg molten steel), and the third sector section (cooling water flow rate of 0.25 L / kg molten steel). The resulting columnar billet is then flame-cut. The surface of the cut billet is ground to remove defects, with 3 mm of the upper surface and 1 mm of the lower surface ground off. The surface oxides are removed by pickling with a 0.1 mol / L sulfuric acid aqueous solution to obtain the finished steel ingot.

[0072] The final high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip has the following alloy element composition: 0.45% N, 0.03% C, 0.40% Si, 0.015% P, 0.003% S, 0.003% O, 21.98% Cr, 5.64% Ni, 5.0% Mn, 2.0% Mo, 0.10% V, 0.10% Cu, 0.10% Ti, 0.02% Nb, 0.016% Al, with the balance being Fe and unavoidable impurities. The Md30 of the high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip is calculated as follows: Md30 = -219.66. The Cr equivalent in the stainless steel strip is 24.59, the Ni equivalent is 9.04, and the pitting corrosion resistance equivalent is 27.67.

[0073] The difference between Example 9 and Example 1 is as follows: Step 1 of the processing technology for high-strength corrosion-resistant nitrogen-alloyed stainless steel strip: Weigh 3N electrolytic iron, pig iron, iron-silicon Fe15Si alloy, iron-copper intermediate alloy CuFe10, 4N pure chromium, 4N pure nickel, and titanium-iron alloy FeTi40 according to the formula of 0.40% Si, 23% Cr, 6.36% Ni, 5% Mn, and the balance Fe, and put them into an electric furnace for smelting. The temperature of the molten steel in the electric furnace is 1680℃. After melting and cleaning, the slag is dephosphorized. After P≤0.015%, the molten steel is tapped at a temperature of 1580℃. The elemental composition of the obtained molten steel is as follows: 0.089% C, 0.015% P, 0. The molten iron contains 0.009% S, 0.40% Si, 22.98% Cr, 6.35% Ni, 0.10% Cu, 0.10% Ti, and the balance Fe. Lime powder is added for complete slag removal, and a reducing slag (CaF2-Al2O3-CaO ternary slag system: CaF2-Al2O3-CaO mass ratio 14:3:3) is re-formed in the ladle. Nitrogen is top-blown, and desulfurization is carried out under a nitrogen atmosphere with stirring to achieve a sulfur content of 0.003%. The molten iron is then decarburized in an AOD furnace, and aluminum granules are added for deoxidation. The AOD smelting temperature is 1650℃. The C content in the molten steel is adjusted to 0.03% and the oxygen content to 30ppm. Iron-vanadium alloy FeV50 is added. The Fe65Nb alloy was smelted at 1650℃, with the V content in the molten steel adjusted to 0.10% and the Nb content to 0.02%. Then, LF refining was performed at 1580℃, adding 99.95% pure manganese and molybdenum particles to adjust the Mn content to 5.00% and the Mo content to 2.00%. Finally, a nitrogen-argon mixture was blown into the bottom of the ladle at a nitrogen-argon volume ratio of 1:2, a flow rate of 25 L / min, and a soft-blowing time of 45 min, adjusting the N content in the molten steel to 0.35%. The steel was then continuously cast to obtain a billet at 1550℃. The billet pulling speed is 1 m / min, and the crystallizer vibration is 5 mm amplitude and 120 times / min. The billet is cooled through the foot roll section (cooling water flow rate of 0.60 L / kg molten steel), the first sector section (cooling water flow rate of 0.45 L / kg molten steel), the second sector section (cooling water flow rate of 0.30 L / kg molten steel), and the third sector section (cooling water flow rate of 0.25 L / kg molten steel). The resulting columnar billet is then flame-cut. The surface of the cut billet is ground to remove defects, with 3 mm of the upper surface and 1 mm of the lower surface ground off. The surface oxides are removed by pickling with a 0.1 mol / L sulfuric acid aqueous solution to obtain the finished steel ingot.

[0074] The final high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip has the following alloy element composition: 0.35% N, 0.03% C, 0.40% Si, 0.015% P, 0.003% S, 0.003% O, 22.98% Cr, 6.35% Ni, 5.0% Mn, 2.0% Mo, 0.10% V, 0.10% Cu, 0.10% Ti, 0.02% Nb, 0.016% Al, with the balance being Fe and unavoidable impurities. The Md30 of the high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip is calculated as follows: Md30 = -207.75. The Cr equivalent in the stainless steel strip is 25.59, the Ni equivalent is 9.75, and the pitting corrosion resistance equivalent is 26.49.

[0075] The difference between Example 10 and Example 1 is as follows: Step 1 of the processing technology for high-strength corrosion-resistant nitrogen-alloyed stainless steel strip: Weigh 3N electrolytic iron, pig iron, iron-silicon Fe15Si alloy, iron-copper intermediate alloy CuFe10, 4N pure chromium, 4N pure nickel, and titanium-iron alloy FeTi40 according to the formula of 0.40% Si, 24% Cr, 7.09% Ni, 5% Mn, and the balance Fe, and put them into an electric furnace for smelting. The temperature of the molten steel in the electric furnace is 1680℃. After melting and cleaning, dephosphorize the slag. After P ≤ 0.015%, tap the molten steel at a temperature of 1580℃. The elemental composition of the obtained molten steel is as follows: 0.089% C, 0.015% P, O The molten steel contains 0.009% S, 0.40% Si, 23.98% Cr, 7.07% Ni, 0.10% Cu, 0.10% Ti, and the balance Fe. Lime powder is added for complete slag removal, and a reducing slag (CaF2-Al2O3-CaO ternary slag system: CaF2-Al2O3-CaO mass ratio 14:3:3) is re-formed in the ladle. Nitrogen is top-blown, and desulfurization is carried out under a nitrogen atmosphere with stirring to achieve a sulfur content of 0.003%. The steel is then decarburized in an AOD furnace, and aluminum granules are added for deoxidation. The AOD smelting temperature is 1650℃. The C content in the molten steel is adjusted to 0.03% and the oxygen content to 30ppm. Iron-vanadium alloy FeV5 is added. The 0 alloy and Fe65Nb alloy were smelted at 1650℃, with the V content in the molten steel adjusted to 0.10% and the Nb content to 0.02%. Then, LF refining was performed at 1580℃, adding 99.95% pure manganese and molybdenum particles to adjust the Mn content in the molten steel to 5.00% and the Mo content to 2.00%. Finally, a nitrogen-argon mixture was blown into the bottom of the ladle at a nitrogen-argon volume ratio of 1:2, a flow rate of 25 L / min, and a soft blowing time of 45 min, adjusting the N content in the molten steel to 0.35%. The steel was then continuously cast to obtain a billet, with the molten steel temperature adjusted to 1550℃. The billet pulling speed is 1 m / min, and the crystallizer vibration is 5 mm amplitude and 120 times / min. The billet is cooled through the foot roll section (cooling water flow rate of 0.60 L / kg molten steel), the first sector section (cooling water flow rate of 0.45 L / kg molten steel), the second sector section (cooling water flow rate of 0.30 L / kg molten steel), and the third sector section (cooling water flow rate of 0.25 L / kg molten steel). The resulting columnar billet is then flame-cut. The surface of the cut billet is ground to remove defects, with 3 mm of the upper surface and 1 mm of the lower surface ground off. The surface oxides are removed by pickling with a 0.1 mol / L sulfuric acid aqueous solution to obtain the finished steel ingot.

[0076] The final high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip has the following alloy element composition: 0.35% N, 0.03% C, 0.40% Si, 0.015% P, 0.003% S, 0.003% O, 23.98% Cr, 7.07% Ni, 5.0% Mn, 2.0% Mo, 0.10% V, 0.10% Cu, 0.10% Ti, 0.02% Nb, 0.016% Al, with the balance being Fe and unavoidable impurities. The Md30 of the high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip is calculated as follows: Md30 = -242.33. The Cr equivalent in the stainless steel strip is 26.59, the Ni equivalent is 10.47, and the pitting corrosion resistance equivalent is 27.31.

[0077] The difference between Example 11 and Example 1 is as follows: Step 1 of the processing technology for high-strength corrosion-resistant nitrogen-alloyed stainless steel strip: Weigh 3N electrolytic iron, pig iron, iron-silicon Fe15Si alloy, iron-copper intermediate alloy CuFe10, 4N pure chromium, 4N pure nickel, and titanium-iron alloy FeTi40 according to the formula of 0.40% Si, 25% Cr, 7.8% Ni, 5% Mn, and the balance Fe, and put them into an electric furnace for smelting. The temperature of the molten steel in the electric furnace is 1680℃. After melting and cleaning, the slag is dephosphorized. After P≤0.015%, the molten steel is tapped at a temperature of 1580℃. The elemental composition of the obtained molten steel is as follows: 0.089% C, 0.015% P, 0. The molten iron contains 0.009% S, 0.40% Si, 24.98% Cr, 7.79% Ni, 0.10% Cu, 0.10% Ti, and the balance Fe. Lime powder is added for complete slag removal, and a reducing slag (CaF2-Al2O3-CaO ternary slag system: CaF2-Al2O3-CaO mass ratio 14:3:3) is re-formed in the ladle. Nitrogen is top-blown, and desulfurization is carried out under a nitrogen atmosphere with stirring to achieve a sulfur content of 0.003%. The molten iron is then decarburized in an AOD furnace, and aluminum granules are added for deoxidation. The AOD smelting temperature is 1650℃. The C content in the molten steel is adjusted to 0.03% and the oxygen content to 30ppm. Iron-vanadium alloy FeV50 is added. The Fe65Nb alloy was smelted at 1650℃, with the V content in the molten steel adjusted to 0.10% and the Nb content to 0.02%. Then, LF refining was performed at 1580℃, adding 99.95% pure manganese and molybdenum particles to adjust the Mn content to 5.00% and the Mo content to 2.00%. Finally, a nitrogen-argon mixture was blown into the bottom of the ladle at a nitrogen-argon volume ratio of 1:2, a flow rate of 25 L / min, and a soft-blowing time of 45 min, adjusting the N content in the molten steel to 0.35%. The steel was then continuously cast to obtain a billet at 1550℃. The billet pulling speed is 1 m / min, and the crystallizer vibration is 5 mm amplitude and 120 times / min. The billet is cooled through the foot roll section (cooling water flow rate of 0.60 L / kg molten steel), the first sector section (cooling water flow rate of 0.45 L / kg molten steel), the second sector section (cooling water flow rate of 0.30 L / kg molten steel), and the third sector section (cooling water flow rate of 0.25 L / kg molten steel). The resulting columnar billet is then flame-cut. The surface of the cut billet is ground to remove defects, with 3 mm of the upper surface and 1 mm of the lower surface ground off. The surface oxides are removed by pickling with a 0.1 mol / L sulfuric acid aqueous solution to obtain the finished steel ingot.

[0078] The final high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip has the following alloy element composition: 0.35% N, 0.03% C, 0.40% Si, 0.015% P, 0.003% S, 0.003% O, 24.98% Cr, 7.79% Ni, 5.0% Mn, 2.0% Mo, 0.10% V, 0.10% Cu, 0.10% Ti, 0.02% Nb, 0.016% Al, with the balance being Fe and unavoidable impurities. The Md30 of the high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip is calculated as follows: Md30 = -173.46. The Cr equivalent in the stainless steel strip is 27.59, the Ni equivalent is 11.19, and the pitting corrosion resistance equivalent is 28.13.

[0079] The difference between Example 12 and Example 1 is as follows: Step 1 of the processing technology for high-strength corrosion-resistant nitrogen-alloyed stainless steel strip: Weigh 3N electrolytic iron, pig iron, iron-silicon Fe15Si alloy, iron-copper intermediate alloy CuFe10, 4N pure chromium, 4N pure nickel, and titanium-iron alloy FeTi40 according to the formula of 0.40% Si, 26% Cr, 8.52% Ni, 5% Mn, and the balance Fe, and put them into an electric furnace for smelting. The temperature of the molten steel in the electric furnace is 1680℃. After melting and cleaning, dephosphorize the slag. After P ≤ 0.015%, tap the molten steel at a temperature of 1580℃. The elemental composition of the obtained molten steel is as follows: 0.089% C, 0.015% P, O The molten steel contains 0.009% S, 0.40% Si, 25.97% Cr, 8.50% Ni, 0.10% Cu, 0.10% Ti, and the balance Fe. Lime powder is added for complete slag removal, and a reducing slag (CaF2-Al2O3-CaO ternary slag system: CaF2-Al2O3-CaO mass ratio 14:3:3) is re-formed in the ladle. Nitrogen is top-blown, and desulfurization is carried out under a nitrogen atmosphere with stirring to achieve a sulfur content of 0.003%. The steel is then decarburized in an AOD furnace, and aluminum granules are added for deoxidation. The AOD smelting temperature is 1650℃. The C content in the molten steel is adjusted to 0.03%, and the oxygen content to 30ppm. Iron-vanadium alloy FeV5 is added. The 0 alloy and Fe65Nb alloy were smelted at 1650℃, with the V content in the molten steel adjusted to 0.10% and the Nb content to 0.02%. Then, LF refining was performed at 1580℃, adding 99.95% pure manganese and molybdenum particles to adjust the Mn content in the molten steel to 5.00% and the Mo content to 2.00%. Finally, a nitrogen-argon mixture was blown into the bottom of the ladle at a nitrogen-argon volume ratio of 1:2, a flow rate of 25 L / min, and a soft blowing time of 45 min, adjusting the N content in the molten steel to 0.35%. The steel was then continuously cast to obtain a billet, with the molten steel temperature adjusted to 1550℃. The billet pulling speed is 1 m / min, and the crystallizer vibration is 5 mm amplitude and 120 times / min. The billet is cooled through the foot roll section (cooling water flow rate of 0.60 L / kg molten steel), the first sector section (cooling water flow rate of 0.45 L / kg molten steel), the second sector section (cooling water flow rate of 0.30 L / kg molten steel), and the third sector section (cooling water flow rate of 0.25 L / kg molten steel). The resulting columnar billet is then flame-cut. The surface of the cut billet is ground to remove defects, with 3 mm of the upper surface and 1 mm of the lower surface ground off. The surface oxides are removed by pickling with a 0.1 mol / L sulfuric acid aqueous solution to obtain the finished steel ingot.

[0080] The final high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip has the following alloy element composition: 0.35% N, 0.03% C, 0.40% Si, 0.015% P, 0.003% S, 0.003% O, 25.97% Cr, 8.50% Ni, 5.0% Mn, 2.0% Mo, 0.10% V, 0.10% Cu, 0.10% Ti, 0.02% Nb, 0.016% Al, with the balance being Fe and unavoidable impurities. The Md30 of the high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip is calculated as follows: Md30 = -311.07. The Cr equivalent in the stainless steel strip is 28.58, the Ni equivalent is 11.90, and the pitting corrosion resistance equivalent is 28.95.

[0081] The difference between Comparative Example 1 and Example 1 is as follows: Step 1 of the processing technology for high-strength corrosion-resistant nitrogen-alloyed stainless steel strip: Weigh 3N electrolytic iron, pig iron, iron-silicon Fe15Si alloy, iron-copper intermediate alloy CuFe10, 4N pure chromium, 4N pure nickel, and titanium-iron alloy FeTi40 according to the formula of 0.40% Si, 22% Cr, 4.02% Ni, 5% Mn, and the balance Fe, and put them into an electric furnace for smelting. The temperature of the molten steel in the electric furnace is 1680℃. After melting and cleaning, the slag is dephosphorized. After P≤0.015%, the molten steel is tapped at a temperature of 1580℃. The elemental composition of the obtained molten steel is as follows: 0.089% C, 0.015% P, 0. The molten steel contains 0.009% S, 0.40% Si, 21.98% Cr, 4.01% Ni, 0.10% Cu, 0.10% Ti, and the balance Fe. Lime powder is added for complete slag removal, and a reducing slag (CaF2-Al2O3-CaO ternary slag system: CaF2-Al2O3-CaO mass ratio 14:3:3) is re-formed in the ladle. Nitrogen is top-blown, and desulfurization is carried out under a nitrogen atmosphere with stirring to achieve a sulfur content of 0.003%. The steel is then decarburized in an AOD furnace, and aluminum granules are added for deoxidation. The AOD smelting temperature is 1650℃. The C content in the molten steel is adjusted to 0.03% and the oxygen content to 30ppm. Iron-vanadium alloy FeV50 is added. The Fe65Nb alloy was smelted at 1650℃, with the V content in the molten steel adjusted to 0.10% and the Nb content to 0.02%. Then, LF refining was performed at 1580℃, adding 99.95% pure manganese and molybdenum particles to adjust the Mn content to 5.00% and the Mo content to 2.00%. Finally, a nitrogen-argon mixture was blown into the bottom of the ladle at a nitrogen-argon volume ratio of 1:2, a flow rate of 25 L / min, and a soft-blowing time of 45 min, adjusting the N content in the molten steel to 0.35%. The steel was then continuously cast to obtain a billet at 1550℃. The billet pulling speed is 1 m / min, and the crystallizer vibration is 5 mm amplitude and 120 times / min. The billet is cooled through the foot roll section (cooling water flow rate of 0.60 L / kg molten steel), the first sector section (cooling water flow rate of 0.45 L / kg molten steel), the second sector section (cooling water flow rate of 0.30 L / kg molten steel), and the third sector section (cooling water flow rate of 0.25 L / kg molten steel). The resulting columnar billet is then flame-cut. The surface of the cut billet is ground to remove defects, with 3 mm of the upper surface and 1 mm of the lower surface ground off. The surface oxides are removed by pickling with a 0.1 mol / L sulfuric acid aqueous solution to obtain the finished steel ingot.

[0082] The final high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip has the following alloy element composition: 0.35% N, 0.03% C, 0.40% Si, 0.015% P, 0.003% S, 0.003% O, 21.98% Cr, 4.01% Ni, 5.0% Mn, 2.0% Mo, 0.10% V, 0.10% Cu, 0.10% Ti, 0.02% Nb, 0.016% Al, with the balance being Fe and unavoidable impurities. The Md30 of the high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip is calculated as follows: Md30 = -126.2. The Cr equivalent in the stainless steel strip is 24.59, the Ni equivalent is 7.41, and the pitting corrosion resistance equivalent is 26.08. The Cr equivalent and Ni equivalent satisfy the following relationship: Y = kX - 8.6, where Y is the Ni equivalent, X is the Cr equivalent, and k is 0.651.

[0083] The difference between Comparative Example 2 and Example 1 is as follows: Step 1 of the processing technology for high-strength corrosion-resistant nitrogen-alloyed stainless steel strip: Weigh 3N electrolytic iron, pig iron, iron-silicon Fe15Si alloy, iron-copper intermediate alloy CuFe10, 4N pure chromium, 4N pure nickel, and titanium-iron alloy FeTi40 according to the formula of 0.40% Si, 22% Cr, 10.10% Ni, 5% Mn, and the balance Fe, and put them into an electric furnace for smelting. The temperature of the molten steel in the electric furnace is 1680℃. After melting and cleaning, the slag is dephosphorized. After P≤0.015%, the molten steel is tapped at a temperature of 1580℃. The elemental composition of the obtained molten steel is as follows: 0.089% C, 0.015% P, 0. The molten iron contains 0.009% S, 0.40% Si, 21.98% Cr, 10.09% Ni, 0.10% Cu, 0.10% Ti, and the balance Fe. Lime powder is added for complete slag removal, and a reducing slag (CaF2-Al2O3-CaO ternary slag system: CaF2-Al2O3-CaO mass ratio 14:3:3) is re-formed in the ladle. Nitrogen is top-blown, and desulfurization is carried out under a nitrogen atmosphere with stirring to achieve a sulfur content of 0.003%. The molten iron is then decarburized in an AOD furnace, and aluminum granules are added for deoxidation. The AOD smelting temperature is 1650℃. The C content in the molten steel is adjusted to 0.03% and the oxygen content to 30ppm. Iron-vanadium alloy FeV5 is added. The 0 alloy and Fe65Nb alloy were smelted at 1650℃, with the V content in the molten steel adjusted to 0.10% and the Nb content to 0.02%. Then, LF refining was performed at 1580℃, adding 99.95% pure manganese and molybdenum particles to adjust the Mn content in the molten steel to 5.00% and the Mo content to 2.00%. Finally, a nitrogen-argon mixture was blown into the bottom of the ladle at a nitrogen-argon volume ratio of 1:2, a flow rate of 25 L / min, and a soft blowing time of 45 min, adjusting the N content in the molten steel to 0.35%. The steel was then continuously cast to obtain a billet, with the molten steel temperature adjusted to 1550℃. The billet pulling speed is 1 m / min, and the crystallizer vibration is 5 mm amplitude and 120 times / min. The billet is cooled through the foot roll section (cooling water flow rate of 0.60 L / kg molten steel), the first sector section (cooling water flow rate of 0.45 L / kg molten steel), the second sector section (cooling water flow rate of 0.30 L / kg molten steel), and the third sector section (cooling water flow rate of 0.25 L / kg molten steel). The resulting columnar billet is then flame-cut. The surface of the cut billet is ground to remove defects, with 3 mm of the upper surface and 1 mm of the lower surface ground off. The surface oxides are removed by pickling with a 0.1 mol / L sulfuric acid aqueous solution to obtain the finished steel ingot.The final high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip has the following alloy element composition: 0.35% N, 0.03% C, 0.40% Si, 0.015% P, 0.003% S, 0.003% O, 21.98% Cr, 10.09% Ni, 5.0% Mn, 2.0% Mo, 0.10% V, 0.10% Cu, 0.10% Ti, 0.02% Nb, 0.016% Al, with the balance being Fe and unavoidable impurities. The Md30 of the high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip is calculated as follows: Md30 = -302.5. The Cr equivalent in the stainless steel strip is 24.59, the Ni equivalent is 13.49, and the pitting corrosion resistance equivalent is 24.56. The Cr equivalent and Ni equivalent satisfy the following relationship: Y = kX - 8.6, where Y is the Ni equivalent, X is the Cr equivalent, and k is 0.899.

[0084] The difference between Comparative Example 3 and Example 1 is as follows: Step 1 of the processing technology for high-strength corrosion-resistant nitrogen-alloyed stainless steel strip: Step 1: Weigh 3N electrolytic iron, pig iron, iron-silicon Fe15Si alloy, iron-copper intermediate alloy CuFe10, 4N pure chromium, 4N pure nickel, and titanium-iron alloy FeTi40 according to the formula of 0.40% Si, 22% Cr, 8% Ni, 5% Mn, and the balance being Fe. Add these materials to an electric furnace for smelting. The temperature of the molten steel in the electric furnace is 1680℃. After melting and cleaning, dephosphorize the slag. After P ≤ 0.015%, tap the molten steel at a temperature of 1580℃. The elemental composition of the obtained molten steel is as follows: 0.089% C The molten iron contains 0.015% P, 0.009% S, 0.40% Si, 21.98% Cr, 7.99% Ni, 0.10% Cu, 0.10% Ti, and the balance Fe. Lime powder is added for complete slag removal. A reducing slag (CaF2-Al2O3-CaO ternary slag system: CaF2-Al2O3-CaO mass ratio 14:3:3) is re-formed in the ladle. Nitrogen is top-blown, and desulfurization is carried out under a nitrogen atmosphere with stirring to achieve a sulfur content of 0.003%. The molten iron is then decarburized in an AOD furnace, and aluminum granules are added for deoxidation. The AOD smelting temperature is 1650℃, and the carbon content in the molten steel is adjusted to 0.0%. The steel was smelted at 1650℃ with 3% oxygen and 30ppm oxygen content, and FeV50 and Fe65Nb alloys were added. The V content was adjusted to 0.10% and Nb content to 0.02%. LF refining was then performed at 1580℃, with the addition of 99.95% pure manganese and molybdenum particles. The Mn content was adjusted to 5.00% and the Mo content to 2.00%. Finally, argon gas was blown into the ladle from the bottom at a flow rate of 25L / min for 15min. Continuous casting was then performed to obtain the billet, with the steel temperature adjusted to 1550℃ and the billet pulling speed at 1m / min. n, Crystallizer vibration: amplitude 5mm, frequency 120 times / min, passing through the foot roller section (cooling water flow rate of 0.60L / kg molten steel), the first sector section (cooling water flow rate of 0.45L / kg molten steel), the second sector section (cooling water flow rate of 0.30L / kg molten steel), and the third sector section (cooling water flow rate of 0.25L / kg molten steel) for cooling. The resulting columnar steel billet is then cut by flame cutting. The surface of the cut steel block is ground to remove defects, with 3mm of the upper surface and 1mm of the lower surface ground off. The surface oxides are removed by pickling with 0.1mol / L sulfuric acid aqueous solution to obtain the finished steel ingot.The final high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip has the following alloy element composition: 0.003% N, 0.03% C, 0.40% Si, 0.015% P, 0.003% S, 0.003% O, 21.98% Cr, 7.99% Ni, 5.0% Mn, 2.0% Mo, 0.10% V, 0.10% Cu, 0.10% Ti, 0.02% Nb, 0.016% Al, with the balance being Fe and unavoidable impurities. The Md30 of the high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip is calculated as follows: Md30 = -81.3. The Cr equivalent in the stainless steel strip is 24.59, the Ni equivalent is 11.39, and the pitting corrosion resistance equivalent is 18.14.

[0085] The difference between Comparative Example 4 and Example 1 is as follows: Step 1 of the processing technology for high-strength corrosion-resistant nitrogen-alloyed stainless steel strip: Step 1: Weigh 3N electrolytic iron, pig iron, iron-silicon Fe15Si alloy, iron-copper intermediate alloy CuFe10, 4N pure chromium, 4N pure nickel, and titanium-iron alloy FeTi40 according to the formula of 0.40% Si, 22% Cr, 8% Ni, 5% Mn, and the balance Fe. Put the materials into an electric furnace for smelting. The temperature of the molten steel in the electric furnace is 1680℃. After melting and cleaning, dephosphorize the slag. After P≤0.015%, tap the molten steel at a temperature of 1580℃. The elemental composition of the obtained molten steel is as follows: 0.089% C, 0.015% P, 0. The molten iron contains 0.009% S, 0.40% Si, 21.98% Cr, 7.99% Ni, 0.10% Cu, 0.10% Ti, and the balance Fe. Lime powder is added for complete slag removal, and a reducing slag (CaF2-Al2O3-CaO ternary slag system: CaF2-Al2O3-CaO mass ratio 14:3:3) is re-formed in the ladle. Nitrogen is top-blown, and desulfurization is carried out under a nitrogen atmosphere with stirring to achieve a sulfur content of 0.003%. The molten iron is then decarburized in an AOD furnace, and aluminum granules are added for deoxidation. The AOD smelting temperature is 1650℃. The C content in the molten steel is adjusted to 0.03% and the oxygen content to 30ppm. Iron-vanadium alloy FeV50 is added. The Fe65Nb alloy was smelted at 1650℃, with the V content in the molten steel adjusted to 0.10% and the Nb content to 0.02%. Then, LF refining was performed at 1580℃, adding 99.95% pure manganese and molybdenum particles to adjust the Mn content to 5.00% and the Mo content to 2.00%. Finally, a nitrogen-argon mixture was blown into the bottom of the ladle at a nitrogen-argon volume ratio of 1:2, a flow rate of 25 L / min, and a soft-blowing time of 10 min, adjusting the N content in the molten steel to 0.15%. The steel was then continuously cast to obtain a billet at 1550℃. The billet pulling speed is 1 m / min, and the crystallizer vibration is 5 mm in amplitude and 120 times / min in frequency. The billet is cooled through the foot roll section (cooling water flow rate of 0.60 L / kg molten steel), the first sector section (cooling water flow rate of 0.45 L / kg molten steel), the second sector section (cooling water flow rate of 0.30 L / kg molten steel), and the third sector section (cooling water flow rate of 0.25 L / kg molten steel). The resulting columnar billet is then cut by flame cutting. The surface of the cut billet is ground to remove defects. 3 mm of the upper surface and 1 mm of the lower surface are ground off. Subsequently, the surface oxides are removed by pickling with 0.1 mol / L sulfuric acid aqueous solution to obtain the finished steel ingot.The final high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip has the following alloy element composition: 0.15% N, 0.03% C, 0.40% Si, 0.015% P, 0.003% S, 0.003% O, 21.98% Cr, 7.99% Ni, 5.0% Mn, 2.0% Mo, 0.10% V, 0.10% Cu, 0.10% Ti, 0.02% Nb, 0.016% Al, with the balance being Fe and unavoidable impurities. The Md30 of the high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip is calculated as follows: Md30 = -149.2. The Cr equivalent in the stainless steel strip is 24.59, the Ni equivalent is 11.39, and the pitting corrosion resistance equivalent is 21.08.

[0086] The difference between Comparative Example 5 and Example 3 is that in step four of the processing technology of high-strength corrosion-resistant nitrogen-alloyed stainless steel strip, the steel strip to be cold-rolled in step three undergoes solution treatment, cold rolling treatment, pickling treatment, and leveling in sequence to obtain the finished high-strength corrosion-resistant nitrogen-alloyed stainless steel strip.

[0087] The difference between Comparative Example 6 and Example 1 is as follows: Step 1 of the processing technology for high-strength corrosion-resistant nitrogen-alloyed stainless steel strip: Step 1: Weigh 3N electrolytic iron, pig iron, iron-silicon Fe15Si alloy, 4N pure chromium, 4N pure nickel, and ferrotitanium alloy FeTi40 according to the formula of 0.40% Si, 22% Cr, 8% Ni, 5% Mn, and the balance being Fe. Add these ingredients to an electric furnace for smelting. The temperature of the molten steel in the electric furnace is 1680℃. After melting and cleaning, dephosphorize the slag. After P ≤ 0.015%, tap the molten steel at a temperature of 1580℃. The elemental composition of the obtained molten steel is as follows: 0.089% C, 0.015% P, 0.00 9% S, 0.40% Si, 21.98% Cr, 7.99% Ni, 0.10% Ti, balance Fe; lime powder is added for complete slag removal, and a reducing slag (CaF2-Al2O3-CaO ternary slag system: CaF2-Al2O3-CaO mass ratio 14:3:3) is re-formed in the ladle. Nitrogen is top-blown, and desulfurization is carried out by stirring under a nitrogen atmosphere to achieve a sulfur content of 0.003%. The molten steel is then decarburized in an AOD furnace, and aluminum granules are added for deoxidation. The AOD smelting temperature is 1650℃, and the C content in the molten steel is adjusted to 0.03% and the oxygen content to 30ppm. Iron-vanadium alloy FeV50 is added. Gold was smelted at 1650℃, with the V content in the molten steel adjusted to 0.10%. Then, LF refining was performed at 1580℃, adding 99.95% pure manganese and molybdenum particles to adjust the Mn content to 5.00% and the Mo content to 2.00%. Finally, a nitrogen-argon mixture was blown into the bottom of the ladle at a nitrogen-argon volume ratio of 1:2, a flow rate of 25 L / min, and a soft-blowing time of 45 min, adjusting the N content in the molten steel to 0.35%. This was followed by continuous casting to obtain a billet, with the molten steel temperature adjusted to 1550℃ and the billet casting speed at 1 m / min. The crystallizer is vibrated with an amplitude of 5 mm and a frequency of 120 times / min. The steel billet is cooled through the foot roller section (cooling water flow rate of 0.60 L / kg molten steel), the first sector section (cooling water flow rate of 0.45 L / kg molten steel), the second sector section (cooling water flow rate of 0.30 L / kg molten steel), and the third sector section (cooling water flow rate of 0.25 L / kg molten steel). The resulting columnar steel billet is then cut by flame cutting. The surface of the cut steel block is ground to remove defects. 3 mm of the upper surface and 1 mm of the lower surface are ground off. Subsequently, the surface oxides are removed by pickling with 0.1 mol / L sulfuric acid aqueous solution to obtain the finished steel ingot. The final stainless steel strip has the following alloy element composition: 0.15% N, 0.03% C, 0.40% Si, 0.015% P, 0.003% S, 0.003% O, 21.98% Cr, 7.99% Ni, 5.0% Mn, 2.0% Mo, 0.10% V, 0.10% Ti, 0.016% Al, with the balance being Fe and unavoidable impurities.The formula for calculating Md30 of the finished stainless steel strip is as follows: Md30 = -170.43. The Cr equivalent in the stainless steel strip is 24.58, the Ni equivalent is 9.04, and the pitting resistance equivalent is 25.67.

[0088] Performance testing: 1. Vickers hardness was determined according to GB / T 4340.1-2024 "Metallic Materials - Vickers Hardness Test Method". 2. Yield strength, tensile strength, and elongation were determined according to GB / T 228.1-2010 "Metallic Materials - Tensile Testing - Part 1: Room Temperature Test Method". 3. Corrosion resistance test method: Stainless steel strips were continuously sprayed with a 5wt% sodium chloride aqueous solution (pH adjusted to 6.5-7.2) at 25±2℃, with a salt spray deposition rate of 2mL / (h·80cm). Continuous spraying was performed, and the neutral salt spray treatment times were 1000h, 1500h, and 2000h. After the experiment, the samples were carefully removed from the salt spray chamber, gently rinsed with running cold water, or the salt deposits were removed from the surface with a sponge, and then immediately dried at 100℃ for 30min. The degree of corrosion or other defects were checked promptly, and the rust spot quantity rating was performed according to GB / T 5944-1986.

[0089] Table 1: Test parameters of stainless steel strips in Examples 1-12 and Comparative Examples 1-6

[0090]

[0091]

[0092] Table 2: Test parameters of stainless steel strips in Examples 1-12 and Comparative Examples 1-6

[0093]

[0094] Combining Examples 1-4 and Comparative Examples 1-2 with Table 1-2, it can be seen that adjusting the alloy composition to optimize the content of austenite and ferrite can improve the mechanical properties and corrosion resistance of the prepared stainless steel strip. From the Schaeffler microstructure curves and the test parameters of Examples 1-4 and Comparative Examples 1-2, it can be seen that the stainless steel strip in Example 3 has similar austenite and ferrite contents, resulting in a duplex stainless steel strip with excellent mechanical properties and also excellent corrosion resistance.

[0095] As can be seen from Example 1 and Comparative Example 6, and Tables 1-2, the addition of Cu and Nb elements to stainless steel strips, combined with the enhanced precipitation treatment process provided in this invention, induces the precipitation of ε-Cu phase and generates Nb(C,N) nanoclusters, which can effectively improve the corrosion resistance of the prepared stainless steel strips and also help to improve the mechanical properties of the stainless steel strips.

[0096] As can be seen from Examples 3, 5-8, and Comparative Examples 3-5, and Table 1-2, nitrogen atoms are dissolved into the stainless steel lattice in an interstitial form, generating solid solution strengthening through lattice distortion. With the increase of nitrogen content, the mechanical strength of the prepared stainless steel strip is significantly improved. At the same time, the strengthening precipitation treatment process provided in this invention induces the precipitation of ε-Cu phase and generates Nb(C,N) nanoclusters. With the increase of nitrogen content, the corrosion resistance of the prepared stainless steel strip can be effectively improved.

[0097] Combining Examples 3 and 9-12 with Table 1-2, it can be seen that as the Cr and Ni equivalents increase and satisfy the following relationship: Y = kX - 8.6, where Y is the Ni equivalent, X is the Cr equivalent, and k is 0.717, the mechanical properties and corrosion resistance of the stainless steel strip show an upward trend. However, this inevitably leads to an increase in overall production costs. Therefore, considering both physicochemical properties and production costs, the optimal production scheme in this invention is the processing technology of the high-strength corrosion-resistant nitrogen-alloyed stainless steel strip in Example 3.

[0098] In summary, the stainless steel strip prepared in this invention exhibits excellent salt corrosion resistance as well as good yield strength, tensile strength, and processing performance, meeting the corrosion resistance requirements in high-chlorine environments. Specifically, the stainless steel strip of this invention has an annual corrosion rate ≤0.01 mm / year in flowing seawater; the stainless steel strip has a yield strength ≥500 MPa, a tensile strength ≥720 MPa, an elongation of 28-35%, and a Vickers hardness of 245-280 HV, thus possessing excellent corrosion resistance along with good yield strength, tensile strength, and processing performance, meeting the corrosion resistance requirements in high-chlorine environments.

[0099] It should be noted that this specific embodiment is merely an explanation of the technical solution of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. High-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip, characterized in that: The chemical composition of the stainless steel strip is as follows (by mass percentage): 0.25-0.45% N, 22-26% Cr, 5-10% Ni, 2-8% Mn, 1.8-2.4% Mo, 0.05-0.2% V, 0.05-0.2% Cu, 0.05-0.2% Ti, 0.01-0.04% Nb, ≤0.02% Al, ≤0.05% C, ≤1.0% Si, ≤0.030% P, ≤0.01% S, ≤0.005% O, with the balance being Fe and unavoidable impurities; the pitting corrosion resistance equivalent of the stainless steel strip = Cr% + 20*C% + 20*N% - 0.5*Mn% - 0.25*Ni% ≥ 22.0; In the stainless steel strip, the Cr equivalent is calculated as Cr% + Mo% + 1.5*Si% + 0.5*Nb, and the Ni equivalent is calculated as Ni% + 30*C% + 0.5*Mn. The Cr equivalent in the stainless steel strip is 24-30%, and the Ni equivalent is 8.5-13.0%. The Cr equivalent and Ni equivalent in the stainless steel strip satisfy the following relationship: Y = kX + B, where Y is the Ni equivalent; X is the Cr equivalent; k is 0.70 to 0.82; and B is -8.6 to -8.

5. The stainless steel strip has an annual corrosion rate of ≤0.01mm / year in flowing seawater; the stainless steel strip has a yield strength of ≥500MPa, a tensile strength of ≥720MPa, an elongation of 28-35%, and a Vickers hardness of 245-280HV. The processing technology of the high-strength corrosion-resistant nitrogen-alloyed stainless steel strip includes the following steps: Step 1, smelting stainless steel ingots according to the chemical composition formula of the high-strength corrosion-resistant nitrogen-alloyed stainless steel strip; Step 2: the stainless steel ingots in Step 1 are successively subjected to forging and hot rolling to obtain rolled steel plates; Step 3, the rolled steel plates in Step 2 are cut and polished to obtain cold-rolled steel strips of a predetermined shape; Step 4, the cold-rolled steel strips in Step 3 are successively subjected to solution treatment, cold rolling, strengthening precipitation treatment, pickling treatment, and leveling to obtain the finished high-strength corrosion-resistant nitrogen-alloyed stainless steel strip. The enhanced precipitation treatment is as follows: after cold rolling, the temperature is raised to 580±5℃ at a rate of 100-200℃ / h and held for 120±5min to induce ε-Cu phase precipitation. Then, forced air cooling is used to lower the temperature to 450±5℃ at a rate of ≥50℃ / min and held for 30±5min to generate Nb(C,N) nanoclusters. Subsequently, forced air cooling is used to lower the temperature to below 400℃ at a rate of ≥50℃ / min. The furnace is then opened and allowed to cool naturally to room temperature to complete the enhanced precipitation treatment.

2. The high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip according to claim 1, characterized in that: The pitting corrosion resistance equivalent of the stainless steel strip is calculated as follows: Cr% + 20*C% + 20*N% - 0.5*Mn% - 0.25*Ni% ≥ 25.

0.

3. The high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip according to claim 1, characterized in that: The chemical composition of the stainless steel strip is as follows (by mass percentage): 0.35-0.45% N, 22-26% Cr, 5-10% Ni, 1.8-2.4% Mo, 4-6% Mn, 0.1-0.2% V, 0.1-0.2% Cu, 0.1-0.2% Ti, 0.02-0.04% Nb, ≤0.02% Al, ≤0.03% C, ≤0.6% Si, ≤0.030% P, ≤0.005% S, ≤0.005% O, with the balance being Fe and unavoidable impurities.

4. A processing method for high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip according to any one of claims 1-3, characterized in that: Includes the following steps: Step 1: Smelting stainless steel ingots according to the chemical composition formula of the high-strength corrosion-resistant nitrogen-alloyed stainless steel strip according to any one of claims 1-3; Step 2: The stainless steel ingots in Step 1 are successively subjected to forging and hot rolling to obtain rolled steel plates; Step 3: The rolled steel plates in Step 2 are cut and polished to obtain steel bars of a predetermined shape to be cold-rolled; Step 4: The steel bars to be cold-rolled in Step 3 are successively subjected to solution treatment, cold rolling, strengthening precipitation treatment, pickling treatment, and leveling to obtain the finished high-strength corrosion-resistant nitrogen-alloyed stainless steel strip; The enhanced precipitation treatment is as follows: after cold rolling, the temperature is raised to 580±5℃ at a rate of 100-200℃ / h and held for 120±5min to induce ε-Cu phase precipitation. Then, forced air cooling is used to lower the temperature to 450±5℃ at a rate of ≥50℃ / min and held for 30±5min to generate Nb(C,N) nanoclusters. Subsequently, forced air cooling is used to lower the temperature to below 400℃ at a rate of ≥50℃ / min. The furnace is then opened and allowed to cool naturally to room temperature to complete the enhanced precipitation treatment.

5. The processing technology of the high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip according to claim 4, characterized in that: The solution treatment in step four is specifically operated as follows: heat the temperature to 1050-1150℃ at a rate of 100-200℃ / h and hold it for 2-4 hours. Then, use forced air cooling to cool the temperature to below 400℃ at a rate of ≥50℃ / min. Open the furnace and let it cool naturally to room temperature to complete the solution treatment of the steel bar to be cold rolled.

6. The processing technology of the high-strength, corrosion-resistant, nitrogen-alloyed stainless steel strip according to claim 4, characterized in that: The enhanced precipitation treatment in step four is specifically operated as follows: After cold rolling, the temperature is raised to 580℃ at 100℃ / h and held for 120min to induce ε-Cu phase precipitation. Then, forced air cooling is used to lower the temperature to 450℃ at a rate of ≥50℃ / min and held for 30min to generate Nb(C,N) nanoclusters. Then, forced air cooling is used to lower the temperature to below 400℃ at a rate of ≥50℃ / min. The furnace is then opened and allowed to cool naturally to room temperature to complete the enhanced precipitation treatment.

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