High-strength stainless steel strip and preparation method thereof

Abstract

The present invention relates to the technical field of stainless steel strips and proposes a high-strength stainless steel strip and a method for producing the same. The method comprises the following steps: smelting, refining, continuous casting, hot rolling, pickling, cold rolling, and annealing to obtain the stainless steel strip; during continuous casting, a crystal refiner is added in an amount of 0.01% to 0.05% by weight of the molten steel; the raw materials for the crystal refiner include the following components by weight: 25 parts aluminum nitride powder, 15 to 30 parts titanium powder, 4 to 6 parts ferroboron powder, and 100 parts iron powder. This technical solution solves the problem of low strength of stainless steel strips in related technologies.

Description

Technical Field

[0001] The present invention relates to the technical field of stainless steel strips, and in particular to a high-strength stainless steel strip and a preparation method thereof. Background Art

[0002] In modern industrial production, stainless steel strips are widely used in many fields such as electronics, automobiles, and aerospace due to their excellent corrosion resistance and machinability. However, with the continuous advancement of technology in various industries and the increasing requirements for product performance, the strength of ordinary stainless steel strips has gradually become unable to meet actual needs.

[0003] If the strength of the stainless steel belt is insufficient, deformation and breakage may occur during processing or use, seriously affecting the quality and reliability of the product. Therefore, in order to broaden the scope of use of stainless steel belts, it is of great significance to develop a high-strength stainless steel belt. Summary of the Invention

[0004] The present invention provides a high-strength stainless steel belt and a preparation method thereof, which solves the problem of low strength of the stainless steel belt in the related art.

[0005] The technical solutions of the present invention are as follows:

[0006] The present invention provides a method for preparing a high-strength stainless steel strip, comprising the following steps: smelting, refining, continuous casting, hot rolling, pickling, cold rolling and annealing to obtain the stainless steel strip;

[0007] During the continuous casting, a crystal refiner is added, wherein the amount of the crystal refiner added is 0.01% to 0.05% of the weight of the molten steel;

[0008] The raw materials of the crystal refining agent include the following components in parts by weight: 25 parts of aluminum nitride powder, 15-30 parts of titanium powder, 4-6 parts of ferroboron powder, and 100 parts of iron powder.

[0009] As a further technical solution, the ferroboron powder is low-carbon ferroboron powder;

[0010] The grades of the low carbon ferroboron powder include one or more of FeB22C0.05, FeB20C0.05, FeB18C0.1, and FeB16C0.1.

[0011] The inventors discovered that using low-carbon ferroboron powder can further improve the strength of stainless steel strip. They speculate that lowering the carbon content in ferroboron powder can prevent excessive carbide formation at grain boundaries, reducing stress concentration points and preventing crack initiation and propagation, thereby further improving the strength of the stainless steel strip.

[0012] As a further technical solution, when the crystal refiner is added, the superheat of the molten steel is 5-10°C.

[0013] In the present invention, when the superheat degree of the molten steel is 5-10° C., the crystal refiner can be better integrated with the molten steel, thereby maximizing the nucleation efficiency of the crystal refiner.

[0014] As a further technical solution, the preparation method of the fine crystal agent includes the following steps: uniformly mixing the raw materials of the fine crystal agent, pressing and molding, and obtaining the fine crystal agent.

[0015] In the present invention, the fine crystal agent has good shape and structural stability through compression molding, and can achieve a certain metallurgical bonding.

[0016] As a further technical solution, during the compression molding, the temperature is 1250-1350° C., the pressure is 16-20 MPa, and the time is 20-30 min.

[0017] As a further technical solution, the hot rolling includes rough rolling and finish rolling. During the rough rolling, the starting rolling temperature is 1000-1050°C, the finishing rolling temperature is 950-980°C, and the total reduction is 50%-60%.

[0018] During the finish rolling, the starting rolling temperature is 850-930° C., the final rolling temperature is 800-840° C., and the total reduction is 40%-50%.

[0019] In the present invention, by optimizing the process parameters during hot rolling, the product surface can be made flat and smooth, the generation of surface defects can be reduced, and the stability of the surface quality can be ensured.

[0020] As a further technical solution, during the cold rolling, the total reduction is 35% to 50%.

[0021] In the present invention, by setting the total reduction during cold rolling to 35% to 50%, surface defects that may occur during hot rolling can be eliminated and the surface quality of the product can be improved.

[0022] As a further technical solution, the annealing includes a first stage annealing and a second stage annealing;

[0023] During the first annealing, the holding temperature is 650-700°C for 10-15 minutes, and then the temperature is lowered to 500-520°C at a cooling rate of 80-100°C / h.

[0024] During the second stage annealing, the holding temperature is 500-520° C., the holding time is 10-20 min, and the temperature is lowered to room temperature at a cooling rate of 40-60° C. / h after holding.

[0025] In the present invention, by setting a specific annealing strategy, the work hardening of the stainless steel strip after cold rolling is eliminated, and the two-stage annealing process releases the internal stress of the stainless steel strip, thereby improving the impact resistance of the stainless steel strip.

[0026] The present invention also provides a high-strength stainless steel belt, which is prepared by the method for preparing the high-strength stainless steel belt.

[0027] As a further technical solution, the stainless steel strip is composed of the following components in weight percentage: C 0.01%-0.03%, Si 0.4%-0.6%, Mn 1.1%-1.5%, P≤0.035%, S≤0.025%, Cr 8%-10%, Ni 4%-6%, and the rest is Fe and other inevitable impurities.

[0028] In the present invention, by optimizing the composition of the stainless steel strip, the overall performance of the stainless steel strip is improved, so that it can meet the growing demand for use, and is conducive to the stainless steel strip being more widely used in a wider range of fields.

[0029] The working principle and beneficial effects of the present invention are:

[0030] In the present invention, a crystal refiner is added during continuous casting. This agent can promote the formation of a large number of fine grains during the solidification process of the molten steel, increase the grain boundary area, strongly hinder the movement of dislocations, and significantly improve the strength of the stainless steel strip. The crystal refiner uses iron powder as a carrier, and is combined with aluminum nitride powder, titanium powder, and ferroboron powder to increase the nucleation rate, while reducing the grain boundary energy and limiting grain growth, thereby achieving the purpose of grain refinement. Furthermore, the addition of ferroboron powder can easily improve the hot working properties of the steel, thereby improving the strength of the stainless steel strip as a whole. DETAILED DESCRIPTION

[0031] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0032] In the following examples and comparative examples, unless otherwise specified, the Fe content in the scrap steel is 98.5 wt %, the Si content in the ferrosilicon is 74.5 wt %, the Mn content in the ferromanganese is 45 wt %, the Cr content in the ferrochrome is 55 wt %, the Ni content in the ferronickel is 63 wt %, the median particle size of the aluminum nitride powder is 3000 mesh, the median particle size of the titanium powder is 2500 mesh, the median particle size of the ferroboron powder is 3000 mesh, the median particle size of the iron powder is 1000 mesh, and the median particle size of the boron powder is 3000 mesh.

[0033] Example 1

[0034] A method for preparing a high-strength stainless steel strip comprises the following steps: blending scrap steel, ferrosilicon, ferromanganese, ferrochrome, and ferronickel according to target composition, smelting, refining, and continuous casting; during continuous casting, when the superheat of the molten steel reaches 5°C, adding a fine grain agent accounting for 0.01% of the weight of the molten steel; performing rough rolling, wherein the rough rolling temperature is 1000°C, the final rolling temperature is 950°C, and the total reduction is 50%; performing finish rolling, wherein the finish rolling temperature is 850°C, the final rolling temperature is 800°C, and the total reduction is 40%; performing pickling; performing cold rolling, wherein the total reduction is 50%; and performing heat-hold annealing at 700°C for 10 minutes. The stainless steel strip is then cooled to room temperature at a cooling rate of 70°C / h to obtain the stainless steel strip.

[0035] The preparation method of the fine crystal agent comprises the following steps: ball-milling 25 parts of aluminum nitride powder, 15 parts of titanium powder, 4 parts of ferroboron powder (the ferroboron powder is medium carbon ferroboron powder, grade FeB20C0.15) and 100 parts of iron powder, and pressing at 1250°C and 16 MPa for 30 minutes to obtain a fine crystal agent;

[0036] The stainless steel strip is composed of the following components in weight percentage: C 0.01%, Si 0.4%, Mn 1.1%, P 0.035%, S 0.025%, Cr 8%, Ni 4%, and the rest is Fe and other inevitable impurities.

[0037] Example 2

[0038] A method for preparing a high-strength stainless steel strip comprises the following steps: blending scrap steel, ferrosilicon, ferromanganese, ferrochrome, and ferronickel according to target composition, smelting, refining, and continuous casting; during continuous casting, when the superheat of the molten steel reaches 10°C, adding a fine grain agent accounting for 0.05% of the weight of the molten steel; performing rough rolling, wherein the rough rolling temperature is 1050°C, the final rolling temperature is 980°C, and the total reduction is 60%; performing finish rolling, wherein the finish rolling temperature is 930°C, the final rolling temperature is 840°C, and the total reduction is 50%; performing pickling; performing cold rolling, wherein the total reduction is 35%; and performing heat-hold annealing at 700°C for 10 minutes. The stainless steel strip is then cooled to room temperature at a cooling rate of 70°C / h to obtain the stainless steel strip.

[0039] The preparation method of the fine crystal agent comprises the following steps: ball-milling 25 parts of aluminum nitride powder, 30 parts of titanium powder, 6 parts of ferroboron powder (the ferroboron powder is medium carbon ferroboron powder, grade FeB20C0.5) and 100 parts of iron powder, and pressing at 1350°C and 20 MPa for 20 minutes to obtain a fine crystal agent;

[0040] The stainless steel strip is composed of the following components in weight percentage: C 0.03%, Si 0.6%, Mn 1.5%, P 0.03%, S 0.02%, Cr 10%, Ni 6%, and the rest is Fe and other inevitable impurities.

[0041] Example 3

[0042] The only difference between this embodiment and embodiment 2 is that in this embodiment, the ferroboron powder is low-carbon ferroboron powder with the brand name FeB20C0.05.

[0043] Example 4

[0044] The only difference between this embodiment and embodiment 2 is that in this embodiment, the ferroboron powder is low-carbon ferroboron powder with the brand name FeB22C0.05.

[0045] Example 5

[0046] The only difference between this embodiment and embodiment 2 is that in this embodiment, the ferroboron powder is low-carbon ferroboron powder with the brand name FeB18C0.1.

[0047] Example 6

[0048] The only difference between this embodiment and embodiment 2 is that in this embodiment, the ferroboron powder is low-carbon ferroboron powder with the brand name FeB16C0.1.

[0049] Example 7

[0050] The only difference between this embodiment and embodiment 6 is that, in this embodiment, annealing includes a first stage annealing and a second stage annealing;

[0051] During the first annealing, the holding temperature is 700°C for 10 min, and then the temperature is lowered to 520°C at a cooling rate of 40°C / h.

[0052] During the second annealing, the holding temperature is 520°C, the holding time is 10 min, and the temperature is cooled to room temperature at a cooling rate of 100°C / h.

[0053] Example 8

[0054] The only difference between this embodiment and embodiment 6 is that, in this embodiment, annealing includes a first stage annealing and a second stage annealing;

[0055] During the first annealing, the holding temperature is 700°C for 10 min, and then the temperature is lowered to 520°C at a cooling rate of 100°C / h.

[0056] During the second annealing, the holding temperature is 520°C for 10 min, and then the temperature is lowered to room temperature at a cooling rate of 40°C / h.

[0057] Example 9

[0058] The only difference between this embodiment and embodiment 6 is that, in this embodiment, annealing includes a first stage annealing and a second stage annealing;

[0059] During the first annealing, the holding temperature is 650°C for 15 min, and then the temperature is lowered to 500°C at a cooling rate of 80°C / h.

[0060] During the second annealing, the holding temperature is 500°C for 20 min, and then the temperature is lowered to room temperature at a cooling rate of 60°C / h.

[0061] Comparative Example 1

[0062] The only difference between this comparative example and Example 1 is that in this comparative example, the preparation method of the fine crystal agent includes the following steps: 25 parts of aluminum nitride powder, 15 parts of titanium powder and 100 parts of iron powder are ball-milled uniformly by weight, and pressed at 1250°C and 16 MPa for 30 minutes to obtain a fine crystal agent.

[0063] Comparative Example 2

[0064] The only difference between this comparative example and Example 1 is that in this comparative example, the preparation method of the fine crystal agent comprises the following steps: 25 parts of aluminum nitride powder, 4 parts of ferroboron powder (the ferroboron powder is medium carbon ferroboron powder, brand FeB20C0.15) and 100 parts of iron powder are ball-milled uniformly by weight, and pressed at 1250°C and 16 MPa for 30 minutes to obtain a fine crystal agent.

[0065] Comparative Example 3

[0066] The only difference between this comparative example and Example 1 is that in this comparative example, the preparation method of the fine crystal agent includes the following steps: 25 parts of aluminum nitride powder, 15 parts of titanium powder, 4 parts of boron powder and 100 parts of iron powder are ball-milled uniformly by weight, and pressed at 1250°C and 16 MPa for 30 minutes to obtain a fine crystal agent.

[0067] Comparative Example 4

[0068] The only difference between this comparative example and Example 1 is that no crystal refining agent is added in this comparative example.

[0069] Experimental Example 1 Tensile Strength Test

[0070] The stainless steel strips prepared in Examples 1 to 6 and Comparative Examples 1 to 4 were tested for tensile strength according to GB / T 228.1-2021 "Tensile tests on metallic materials - Part 1: Room temperature test methods", where the test rate was 0.008s. -1 The test results are shown in Table 1 below.

[0071] Table 1 Tensile strength test results

[0072]

[0073] A comparison of Example 1 with Comparative Examples 1-4 demonstrates that the addition of a crystal refiner consisting of aluminum nitride powder, titanium powder, ferroboron powder, and iron powder during continuous casting significantly improves the tensile strength of the stainless steel strip. A comparison of Example 2 with Examples 3-6 demonstrates that the use of low-carbon ferroboron powder further enhances the tensile strength of the stainless steel strip.

[0074] Experimental Example 2 Impact Resistance Test

[0075] The stainless steel strips prepared in Examples 6-9 were tested for their room temperature absorbed energy (KV2) according to GB / T 229-2020, "Charpy Pendulum Impact Test Method for Metallic Materials." V-notched specimens were used for the tests, using a 2 mm pendulum hammer blade. The test results are shown in Table 2.

[0076] Table 2 Impact resistance test

[0077]

[0078] Comparison between Example 6 and Examples 7 to 9 shows that the impact resistance of the stainless steel strip is significantly improved through the two-stage annealing process.

[0079] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a high-strength stainless steel strip, characterized in that: The following steps are involved: After smelting, refining, continuous casting, hot rolling, pickling, cold rolling and annealing, a stainless steel strip is obtained; During the continuous casting, a crystal refiner is added, wherein the amount of the crystal refiner added is 0.01% to 0.05% of the weight of the molten steel; The raw materials of the crystal refining agent include the following components in parts by weight: 25 parts of aluminum nitride powder, 15-30 parts of titanium powder, 4-6 parts of ferroboron powder, and 100 parts of iron powder; The preparation method of the fine crystal agent comprises the following steps: uniformly mixing the raw materials of the fine crystal agent, and pressing and molding to obtain the fine crystal agent; During the compression molding, the temperature is 1250-1350° C., the pressure is 16-20 MPa, and the time is 20-30 minutes.

2. The method for preparing a high-strength stainless steel strip according to claim 1, characterized in that: The ferroboron powder is low-carbon ferroboron powder; The grades of the low carbon ferroboron powder include one or more of FeB22C0.05, FeB20C0.05, FeB18C0.1, and FeB16C0.

1.

3. The method for preparing a high-strength stainless steel strip according to claim 1, wherein: When the crystal refining agent is added, the superheat of the molten steel is 5-10°C.

4. The method for preparing a high-strength stainless steel strip according to claim 1, wherein: The hot rolling includes rough rolling and finish rolling. During the rough rolling, the starting rolling temperature is 1000-1050°C, the finishing rolling temperature is 950-980°C, and the total reduction is 50%-60%. During the finish rolling, the starting rolling temperature is 850-930° C., the final rolling temperature is 800-840° C., and the total reduction is 40%-50%.

5. The method for preparing a high-strength stainless steel strip according to claim 1, characterized in that: During the cold rolling, the total reduction is 35% to 50%.

6. The method for preparing a high-strength stainless steel strip according to claim 1, wherein: The annealing includes a first stage annealing and a second stage annealing; During the first annealing, the holding temperature is 650-700°C for 10-15 minutes, and then the temperature is lowered to 500-520°C at a cooling rate of 80-100°C / h. During the second stage annealing, the holding temperature is 500-520° C., the holding time is 10-20 min, and the temperature is lowered to room temperature at a cooling rate of 40-60° C. / h after holding.

7. A high-strength stainless steel belt, characterized in that: The high-strength stainless steel strip is prepared by the preparation method of any one of claims 1 to 6.

8. The high-strength stainless steel strip according to claim 7, characterized in that: The stainless steel strip is composed of the following components in weight percentage: C 0.01%-0.03%, Si 0.4%-0.6%, Mn 1.1%-1.5%, P≤0.035%, S≤0.025%, Cr 8%-10%, Ni 4%-6%, and the rest is Fe and other inevitable impurities.

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