An austenitic stainless steel for a clamp and a method for manufacturing the same

Abstract

The application provides an austenitic stainless steel for a clamp and a manufacturing method thereof, which comprises the following components in percentage by weight: carbon <0.15%, silicon <1.00%, manganese 1.00-2.00%, phosphorus <0.035%, sulfur <0.003%, chromium 16.00-18.00%, nickel 6.00-8.50%, and other trace elements and iron balance. The application has the beneficial effect that the content of Ni in the austenitic stainless steel for the clamp is 6.00%-8.50%, and the content of Cr is 16.00-18.00%, which is lower than the content of Ni in the existing product, i.e. 8.00%-10.00%, and the content of Cr, i.e. 18.00%-20.00%, and the production cost is low; the stainless steel clamp product produced by the manufacturing method has the characteristics of low production cost, wide hardness grade range (HV150-480), excellent surface BQ property and matrix BQ property, and strong applicability.

Description

Technical Field

[0001] This invention belongs to the field of austenitic stainless steel technology, and in particular relates to an austenitic stainless steel for clamps and its manufacturing method. Background Technology

[0002] As fasteners and an important component of urban secondary water supply systems, clamps have high requirements for airtightness, watertightness, wind pressure resistance, and thermal insulation. The main materials used for clamps include galvanized steel, PP, copper, and stainless steel. With the rapid development of the domestic electric vehicle industry and public concern about water pollution in urban secondary water supply systems, clamps are being used more and more widely in automotive pipe connections and water supply systems.

[0003] On the one hand, ordinary austenitic stainless steel materials come in a wide variety of types and quality levels, resulting in poor quality control (BQ) during grinding and polishing. This manifests in surface needle-indentation defects occurring in 20%-30% of the surface, affecting aesthetics and corrosion resistance. The matrix also contains numerous oxide particles, ranging from 10-50 per unit area, leading to low polishing yield, low surface processing efficiency, and high production costs. On the other hand, existing austenitic stainless steels exhibit uneven hardness when used in the production of clamps, with a range of 10-30 HV, affecting service life. Furthermore, existing manufacturing methods produce hardness grades of 170-200 HV, a narrow range that cannot meet the hardness requirements of various operating conditions. In addition, existing compositions contain more than 8.00% precious metals such as Ni, resulting in high usage costs. Summary of the Invention

[0004] In view of this, the present invention aims to provide an austenitic stainless steel for clamps and its manufacturing method. The stainless steel clamps produced by this manufacturing method have a wide range of hardness grades (HV150-480), excellent BQ performance, high cost performance, and are suitable for user needs in different usage environments.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] An austenitic stainless steel for clamps comprises the following components by weight percentage: carbon <0.15%, silicon <1.00%, manganese 1.00-2.00%, phosphorus <0.035%, sulfur <0.003%, chromium 16.00-18.00%, nickel 6.00-8.50%, and other trace elements and balance iron.

[0007] A method for manufacturing austenitic stainless steel for clamps includes the following steps:

[0008] S1. After the raw materials pass through the processes of blast furnace molten iron, dephosphorization converter, electric furnace, and AOD furnace, the austenitic stainless steel of the above composition is obtained, and the molten steel is continuously cast into steel billets.

[0009] S2. The obtained steel billet is subjected to hot rolling, black sheet annealing shot blasting pickling, cold rolling, cold coil annealing pickling, finishing, secondary rolling, and degreasing cleaning in sequence to obtain austenitic stainless steel for clamps.

[0010] Furthermore, in step S1, the calming time for smelting and continuous casting into steel billets is 15-25 minutes, and the soft blowing time is 15-30 minutes.

[0011] Furthermore, the annealing process of the black steel coil in step S2 adopts a parabolic annealing temperature of 800-1200℃.

[0012] And / or, in step S2, the shot blasting speed is 1800-1900 rpm, and the ratio of shot blasting S110 to S170 is 2:1;

[0013] And / or, the black leather roll annealing shot blasting pickling in step S2 includes sulfuric acid pickling and mixed acid pickling, with a sulfuric acid concentration of 230-300 g / L, a sulfuric acid pickling temperature of 70-80°C, a mixed acid pickling temperature of 45-60°C, a nitric acid concentration of 100-180 g / L, and a hydrofluoric acid concentration of 20-50 g / L.

[0014] Furthermore, the cold rolling in step S2 consists of 5%-8% pre-rolling and 50%-60% single rolling;

[0015] In step S2, the cold rolling annealing and pickling process uses a stepped annealing temperature of 1000-1190℃.

[0016] Furthermore, the inner rollers of the cold coil annealing furnace in step S2 adopt a composite roller shape;

[0017] And / or, the composite roller type includes zero-convexity fiber material rollers and convexity ceramic material rollers, with the continuous use time of fiber material rollers ≤130h and the continuous use time of ceramic material rollers ≤12h.

[0018] Furthermore, the cold rolling annealing pickling in step S2 includes a neutral salt electrolytic pickling process and a mixed acid pickling process;

[0019] And / or, in the neutral salt electrolytic pickling process, the concentration of sodium sulfate is 100-220 g / L, and the temperature of sodium sulfate is 70-85℃;

[0020] And / or, the acid pickling temperature is 50-65℃, the nitric acid concentration is 60-120g / l, and the hydrofluoric acid concentration is 5-30g / l.

[0021] Furthermore, the elongation rate during the finishing process in step S2 is 1%-5%;

[0022] And / or, the secondary rolling deformation rate in step S2 is 5%-15%;

[0023] And / or, the degreasing cleaning in step S2 uses an alkaline solution, a cleaning temperature of 80-100℃, and a cleaning speed of 10-20m / min.

[0024] Furthermore, it also includes step S3: performing transverse and longitudinal hardness tests on the stainless steel sheet and strip products from step S2 to obtain broad-spectrum austenitic stainless steel.

[0025] Preferably, for transverse and longitudinal hardness testing, an electronic micro Vickers hardness tester is used to measure the standard sample in both the transverse and longitudinal directions. Measurements are taken at 20mm intervals, for a total of 10 points, and the range value is taken. If the range value is ≤5HV, austenitic stainless steel of grade HV150-480 is obtained.

[0026] Furthermore, it also includes step S4: performing microstructure analysis on the stainless steel sheet and strip product from step S2 to obtain austenitic stainless steel with excellent BQ properties.

[0027] Preferably, in step S4, the stainless steel strip product is polished with 500#-1000# wet sandpaper. A circular sample with a diameter of 2mm is taken and the oxide particles are counted under 100x magnification. If there are ≤5 particles in the unit circle, then austenitic stainless steel with excellent matrix BQ properties is obtained.

[0028] In step S4, a 100mm*500mm sample of stainless steel sheet / strip is taken and the area of ​​indented particles is calculated under 50x magnification. The defect area is used as the numerator and the sample area is used as the denominator to calculate the needle-indentation defect rate. An incidence rate ≤10% indicates that austenitic stainless steel with excellent surface quality (BQ) has been obtained.

[0029] Compared with the prior art, the austenitic stainless steel for clamps and its manufacturing method described in this invention have the following advantages:

[0030] 1. The austenitic stainless steel for clamps described in this invention has a Ni content of 6.00%-8.50% and a chromium content of 16.00%-18.00%, which is lower than the Ni content of 8.00%-10.00% and the Cr content of 18.00%-20.00% in existing products, resulting in lower production costs.

[0031] 2. The austenitic stainless steel for clamps described in this invention has a 15-25 minute calming time and a 15-30 minute soft blowing time during smelting and continuous casting into steel billets. It has few oxidizing particles in the matrix, with ≤5 particles per unit area, excellent matrix BQ properties, and high polishing efficiency.

[0032] 3. The austenitic stainless steel used for clamps described in this invention employs a parabolic annealing temperature of 800-1200℃ in the annealing process of black steel coils. The cold-rolled annealing process uses a stepped annealing temperature of 1000-1190℃. These annealing temperatures differ from the isothermal or heated annealing techniques of existing technologies, resulting in a small difference in hardness between the transverse and longitudinal directions of the strip (≤5HV), uniform and stable hardness, and a long service life.

[0033] 4. The austenitic stainless steel used for clamps described in this invention has a shot blasting speed of 1850 rpm, a shot blasting ratio of S110 to S170 of 2:1, few oxidizing particles in the matrix, ≤5 particles per unit area, and excellent matrix BQ properties.

[0034] 5. The cold rolling process described in this invention consists of 5%-8% pre-rolling + 50%-60% single rolling + 5%-15% secondary rolling deformation, resulting in a wide range of product hardness grades (HV150-480) to meet the hardness requirements under different working conditions in various fields.

[0035] 6. The inner rollers of the cold coil annealing furnace described in this invention adopt a composite roller shape, wherein rollers 1#-3# are made of zero-convexity fiber material, and rollers 4#-6# are made of 0.1µm convexity ceramic material. The continuous service time of the fiber material rollers is ≤120h, and the continuous service time of the ceramic material rollers is ≤12h. The needle pressure defect rate is ≤10%, and the surface quality is excellent. Attached Figure Description

[0036] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0037] Figure 1 This is a schematic diagram of typical matrix oxidation particle defects, which is a comparative example of the present invention.

[0038] Figure 2 This is a schematic diagram of the substrate surface in Embodiment 1 of the present invention. Detailed Implementation

[0039] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0040] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0041] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0042] Example 1:

[0043] After passing through blast furnace molten iron, dephosphorization converter, electric furnace, and AOD furnace, the raw materials are used to obtain molten steel containing 0.12% carbon, 0.51% silicon, 1.80% manganese, 0.030% phosphorus, 0.002% sulfur, 16.46% chromium, 6.10% nickel, and other trace elements and iron balance.

[0044] When the molten steel is continuously cast into a billet, the calming time is 20 minutes and the soft blowing time is 30 minutes. The black steel coil is annealed using a parabolic annealing temperature, and the hot coil thickness is 5.0 mm.

[0045] 5.0 950 1020 1080 1060 1020 950

[0046] The shot blasting speed for the black steel coils was 1850 rpm, with a shot blasting S110 to S170 ratio of 2:1. Pickling of the black steel coils included sulfuric acid pickling and mixed acid pickling. The sulfuric acid concentration was 250 g / L, and the sulfuric acid pickling temperature was 70℃. The mixed acid pickling process used a mixed acid pickling temperature of 50℃, a nitric acid concentration of 130 g / L, and a hydrofluoric acid concentration of 25 g / L. The cold-rolled pre-rolling deformation rate was 8%, the total deformation rate was 50%, and the rolling thickness was 2.5 mm.

[0047] The cold rolling annealing process uses a stepped annealing temperature, and the cold rolling thickness is 2.5mm.

[0048] 2.5 1090 1130 1160 1180 1190

[0049] The inner rollers of the cold coil annealing furnace adopt a composite roller shape, with rollers #1-3 using zero-convexity fiber material and rollers #4-6 using 0.1µm convexity ceramic material. The continuous service time for the fiber material rollers is 110 hours, and for the ceramic material rollers, it is 10 hours. Cold coil pickling includes a neutral salt electrolytic pickling process and a mixed acid pickling process. In the neutral salt electrolytic pickling process, the sodium sulfate concentration is 150 g / L, and the sodium sulfate temperature is 75℃. The mixed acid pickling temperature is 55℃, the nitric acid concentration is 100 g / L, and the hydrofluoric acid concentration is 15 g / L.

[0050] The finishing process has an elongation rate of 3%, a secondary rolling deformation rate of 8%, and a finished product thickness of 2.3 mm.

[0051] The degreasing and cleaning process used an alkaline solution at a temperature of 95℃ and a cleaning speed of 12m / min. The manufactured stainless steel strip products were tested for transverse and longitudinal hardness using an electronic micro Vickers hardness tester. Measurements were taken at 20mm intervals, for a total of 10 points. The range was recorded, with an average value of 475HV and a range of 4HV, yielding austenitic stainless steel with a grade of HV480±5.

[0052] The manufactured stainless steel sheet and strip products were polished with 500#-1000# wet sandpaper. Using a circular sample with a diameter of 2mm, the oxide particles were counted under 100x magnification. Three particles were found in each unit circle, resulting in austenitic stainless steel with excellent matrix BQ properties.

[0053] A 100mm*500mm sample was taken from the manufactured stainless steel sheet and strip products, and the area of ​​indented particles was calculated under 50x magnification. The needle indentation defect rate was calculated with the defect area as the numerator and the sample area as the denominator. The rate was 3.5%, and austenitic stainless steel with excellent surface quality was obtained.

[0054] Example 2:

[0055] After passing through blast furnace molten iron, dephosphorization converter, electric furnace, and AOD furnace, the raw materials yield molten steel containing 0.12% carbon, 0.74% silicon, 0.78% manganese, 0.030% phosphorus, 0.002% sulfur, 16.42% chromium, 6.83% nickel, and other trace elements and iron balance. The continuous casting of the molten steel into billets involves a 25-minute settling time and a 25-minute soft-blowing time. The black steel coils are annealed using a parabolic annealing temperature, with a hot-rolled coil thickness of 4.0 mm.

[0056] 4.0 1000 1080 1160 1090 1060 1040

[0057] The shot blasting speed for black steel coils is 1850 rpm, and the ratio of S110 to S170 shot is 2:1. Pickling of the black steel coils includes sulfuric acid pickling and mixed acid pickling. The sulfuric acid concentration is 260 g / L, and the sulfuric acid pickling temperature is 78℃. The mixed acid pickling process uses a mixed acid pickling temperature of 55℃, a nitric acid concentration of 150 g / L, and a hydrofluoric acid concentration of 30 g / L.

[0058] The cold-rolled pre-rolling deformation rate is 8%, the total deformation rate is 55%, the rolling thickness is 1.8mm, and the cold coil annealing process adopts a stepped annealing temperature of 1000-1190℃.

[0059] 1.8 1060 1100 1130 1150 1160

[0060] The inner rollers of the cold coil annealing furnace adopt a composite roller shape, with rollers #1-3 using zero-convexity fiber material and rollers #4-6 using 0.1µm convexity ceramic material. The continuous service time of the fiber material rollers is 100 hours, and that of the ceramic material rollers is 8.5 hours. The cold coil pickling includes a neutral salt electrolytic pickling process and a mixed acid pickling process. In the neutral salt electrolytic pickling process, the concentration of sodium sulfate is 180 g / L, and the temperature of sodium sulfate is 78℃. The mixed acid pickling temperature is 60℃, the concentration of nitric acid is 150 g / L, and the concentration of hydrofluoric acid is 10 g / L.

[0061] The finishing process elongation is 2.5%, the secondary rolling deformation rate is 15%, and the finished product thickness is 1.53 mm. Degreasing and cleaning are performed using an alkaline solution at a temperature of 90℃ and a cleaning speed of 15 m / min.

[0062] The transverse and longitudinal hardness of the manufactured stainless steel sheet and strip products were tested using an electronic micro Vickers hardness tester. Measurements were taken at 20mm intervals, for a total of 10 points. The range value was then recorded. The average value was 322 HV, and the range was 2 HV, resulting in austenitic stainless steel with a grade of HV320±5.

[0063] The manufactured stainless steel sheet and strip products are polished with 500#-1000# wet sandpaper. Using a circular sample with a diameter of 2mm, the oxide particles are counted under 100x magnification. Two particles are found in each unit circle, resulting in austenitic stainless steel with excellent matrix BQ properties.

[0064] A 100mm*500mm sample was taken from the manufactured stainless steel sheet and strip products, and the area of ​​indented particles was calculated under 50x magnification. The incidence of needle-pressing defects was calculated with the defect area as the numerator and the sample area as the denominator. The incidence rate was 5.5%, resulting in austenitic stainless steel with excellent surface quality.

[0065] Example 3:

[0066] After passing through blast furnace, dephosphorization converter, electric furnace, and AOD furnace, molten steel with a composition of 0.04% carbon, 0.42% silicon, 1.00% manganese, 0.022% phosphorus, 0.002% sulfur, 18.13% chromium, 8.01% nickel, and other trace elements and iron balance is obtained. The steel is continuously cast into billets with a settling time of 15 minutes and a soft-blowing time of 30 minutes.

[0067] The black steel coil is annealed using a parabolic annealing temperature, with a hot coil thickness of 3.0 mm.

[0068] 3.0 1100 1120 1170 1100 1100 1060

[0069] The shot blasting speed for the black steel coils is 1850 rpm, with a shot blasting S110 to S170 ratio of 2:1. Pickling of the black steel coils includes sulfuric acid pickling and mixed acid pickling. The sulfuric acid concentration is 240 g / L, and the sulfuric acid pickling temperature is 80℃. The mixed acid pickling process uses a mixed acid pickling temperature of 60℃, a nitric acid concentration of 180 g / L, and a hydrofluoric acid concentration of 50 g / L. The cold rolling pre-rolling deformation rate is 5%, the total deformation rate is 60%, and the rolling thickness is 1.2 mm. The cold coil annealing process uses a stepped annealing temperature, with an annealing temperature of 1000-1190℃.

[0070] 1.2 1040 1080 1110 1130 1140

[0071] The inner rollers of the cold coil annealing furnace adopt a composite roller shape, with rollers #1-3 using zero-convexity fiber material and rollers #4-6 using 0.1µm convexity ceramic material. The continuous service time of the fiber material rollers is 112 hours, and that of the ceramic material rollers is 10.4 hours. Cold coil pickling includes a neutral salt electrolytic pickling process and a mixed acid pickling process. In the neutral salt electrolytic pickling process, the concentration of sodium sulfate is 215 g / L, and the temperature is 82℃. The mixed acid pickling temperature is 65℃, the nitric acid concentration is 120 g / L, and the hydrofluoric acid concentration is 28 g / L.

[0072] The finishing elongation rate was 1.8%. The secondary rolling deformation rate was 8.3%, and the finished thickness was 1.10 mm. Degreasing and cleaning were performed using an alkaline solution at a temperature of 95℃ and a cleaning speed of 18 m / min. The transverse and longitudinal hardness of the manufactured stainless steel strip was tested using an electronic micro Vickers hardness tester. Measurements were taken at 20 mm intervals, for a total of 10 points. The range was recorded, with an average value of 148 HV and a range of 2 HV, yielding austenitic stainless steel with a grade of HV150±5.

[0073] The manufactured stainless steel sheet and strip products were polished with 500#-1000# wet sandpaper. Using a circular sample with a diameter of 2mm, the oxide particles were counted under 100x magnification. There were 0 particles in the unit circle, resulting in austenitic stainless steel with excellent matrix BQ properties.

[0074] A 100mm*500mm sample was taken from the manufactured stainless steel sheet and strip products, and the area of ​​indented particles was calculated under 50x magnification. The needle indentation defect rate was calculated with the defect area as the numerator and the sample area as the denominator. The rate was 6.9%, and austenitic stainless steel with excellent surface quality was obtained.

[0075] Example 4:

[0076] After passing through blast furnace hot metal, dephosphorization converter, electric furnace, and AOD furnace, the raw materials yield molten steel containing 0.02% carbon, 0.40% silicon, 1.52% manganese, 0.025% phosphorus, 0.003% sulfur, 18.25% chromium, 8.01% nickel, and other trace elements and the balance iron. The molten steel is continuously cast into billets with a settling time of 20 minutes and a soft-blowing time of 20 minutes. The black steel coils are annealed using a parabolic annealing temperature, with a hot-rolled coil thickness of 2.0 mm.

[0077] 3.0 1120 1140 1180 1130 1110 1090

[0078] The shot blasting speed for the black steel coils is 1850 rpm, with a shot blasting S110 to S170 ratio of 2:1. Pickling of the black steel coils includes sulfuric acid pickling and mixed acid pickling. The sulfuric acid concentration is 235 g / L, and the sulfuric acid pickling temperature is 75℃. The mixed acid pickling process uses a mixed acid pickling temperature of 52℃, a nitric acid concentration of 165 g / L, and a hydrofluoric acid concentration of 25 g / L. The cold-rolled pre-rolling deformation rate is 5%, the total deformation rate is 60%, and the rolling thickness is 0.8 mm. The cold coil annealing process uses a stepped annealing temperature, with an annealing temperature of 1000-1190℃.

[0079] 0.8 1020 1060 1090 1110 1120

[0080] The inner rollers of the cold coil annealing furnace adopt a composite roller shape, with rollers #1-3 using zero-convexity fiber material and rollers #4-6 using 0.1µm convexity ceramic material. The continuous service time of the fiber material rollers is 93 hours, and that of the ceramic material rollers is 8.3 hours. Cold coil pickling includes a neutral salt electrolytic pickling process and a mixed acid pickling process. In the neutral salt electrolytic pickling process, the concentration of sodium sulfate is 130 g / L, and the temperature is 80℃. The mixed acid pickling temperature is 58℃, the nitric acid concentration is 70 g / L, and the hydrofluoric acid concentration is 10 g / L.

[0081] The finishing process resulted in an elongation of 2.2%, a secondary rolling deformation rate of 25%, and a finished product thickness of 0.6 mm. Degreasing and cleaning were performed using an alkaline solution at a temperature of 98℃ and a cleaning speed of 20 m / min. The manufactured stainless steel strip was tested for transverse and longitudinal hardness using an electronic micro Vickers hardness tester. Measurements were taken at 20 mm intervals, for a total of 10 points. The range was recorded, with an average value of 202 HV and a range of 2 HV, yielding an austenitic stainless steel grade of HV200±5.

[0082] The manufactured stainless steel sheet and strip products were polished using 500#-1000# wet sandpaper. Using a circular sample with a diameter of 2mm, the oxide particle count was performed under 100x magnification. Two particles were found within each unit circle, indicating excellent matrix BQ (bulk quality) of austenitic stainless steel. A 100mm*500mm sample was taken from the manufactured stainless steel sheet and strip products, and the area of ​​indented particles was calculated under 50x magnification. Using the defect area as the numerator and the sample area as the denominator, the needle-indentation defect rate was calculated. The rate was 3.0%, indicating excellent surface BQ of austenitic stainless steel.

[0083] Comparative Example 1: The difference from Example 1 is that the calming time for molten steel to be continuously cast into billets is 20 min and the soft blowing time is 10 min.

[0084] The transverse and longitudinal hardness of the manufactured stainless steel sheet and strip products were tested using an electronic micro Vickers hardness tester. Measurements were taken at 20mm intervals, for a total of 10 points. The range value was recorded, with an average value of 477 HV and a range of 3 HV, yielding an austenitic stainless steel grade of HV480±5. The manufactured stainless steel sheet and strip products were polished with 500#-1000# wet sandpaper. Using a 2mm diameter circular sample, the oxide particles were counted under 100x magnification. A count of 16 particles per unit circle indicates an austenitic stainless steel with excellent matrix BQ (bonding quality).

[0085] A 100mm*500mm sample was taken from the manufactured stainless steel sheet and strip products, and the area of ​​indented particles was calculated under 50x magnification. The needle indentation defect rate was calculated with the defect area as the numerator and the sample area as the denominator. The rate was 13.4%, and austenitic stainless steel with excellent surface quality was obtained.

[0086] Comparative Example 2: The difference from Example 2 is that the calming time for molten steel to be continuously cast into billets is 10 min and the soft blowing time is 25 min.

[0087] The transverse and longitudinal hardness of the manufactured stainless steel sheet and strip products were tested using an electronic micro Vickers hardness tester. Measurements were taken at 20mm intervals, for a total of 10 points. The range was recorded, with an average value of 323 HV and a range of 4 HV, yielding an austenitic stainless steel grade of HV320±5. The manufactured stainless steel sheet and strip products were polished with 500#-1000# wet sandpaper. Using a 2mm diameter circular sample, oxide particles were counted under 100x magnification. A count of 18 particles per unit circle indicates an austenitic stainless steel with excellent matrix BQ (bonding quality).

[0088] A 100mm*500mm sample was taken from the manufactured stainless steel sheet and strip products, and the area of ​​indented particles was calculated under 50x magnification. The needle indentation defect rate was calculated with the defect area as the numerator and the sample area as the denominator. The rate was 15.3%, and austenitic stainless steel with excellent surface quality was obtained.

[0089] Comparative Example 3: The difference from Example 3 is that the black steel coil was annealed at an isothermal annealing temperature and the thickness of the hot coil was 3.0 mm.

[0090] 3.0 1150 1150 1150 1150 1150 1150

[0091] The cold rolling annealing process adopts isothermal annealing temperature, with an annealing temperature of 1000-1190℃.

[0092] 1.2 1130 1130 1130 1130 1130

[0093] The transverse and longitudinal hardness of the manufactured stainless steel sheet and strip products were tested using an electronic micro Vickers hardness tester. Measurements were taken at 20mm intervals, for a total of 10 points, and the range was recorded. An average value of 143 HV and a range of 10 HV indicate austenitic stainless steel. The manufactured stainless steel sheet and strip products were polished with 500#-1000# wet sandpaper. Using a 2mm diameter circular sample, the oxide particles were counted under 100x magnification. One particle per unit circle indicates austenitic stainless steel with excellent matrix BQ (bonding quality).

[0094] A 100mm*500mm sample was taken from the manufactured stainless steel sheet and strip products, and the area of ​​indented particles was calculated under 50x magnification. The incidence of needle-pressing defects was calculated with the defect area as the numerator and the sample area as the denominator. The incidence rate was 15.7%, and austenitic stainless steel with excellent surface quality was obtained.

[0095] Comparative Example 4: The difference from Example 1 is that the shot blasting speed of the black steel coil was 2150 rpm, and the ratio of S110 to S170 shot blasting was 1:2. The transverse and longitudinal hardness of the manufactured stainless steel strip was tested using an electronic micro Vickers hardness tester. Measurements were taken at 20 mm intervals, for a total of 10 points. The range was recorded, with an average value of 476 HV and a range of 3 HV, yielding austenitic stainless steel with a grade of HV480±5.

[0096] The manufactured stainless steel sheet and strip products were polished using 500#-1000# wet sandpaper. Using a circular sample with a diameter of 2mm, the oxide particle count was performed under 100x magnification. Eight particles were found within each unit circle, indicating excellent matrix BQ (bulk quality) of austenitic stainless steel. A 100mm*500mm sample was taken from the manufactured stainless steel sheet and strip products, and the area of ​​indented particles was calculated under 50x magnification. Using the defect area as the numerator and the sample area as the denominator, the needle-indentation defect rate was calculated. The rate was 14.0%, indicating excellent surface BQ of austenitic stainless steel.

[0097] Comparative Example 5: The difference from Example 1 is that the shot blasting speed of the black steel coil was 2150 rpm, and the ratio of S110 to S170 shot blasting was 1:1. The transverse and longitudinal hardness of the manufactured stainless steel strip was tested using an electronic micro Vickers hardness tester. Measurements were taken at 20 mm intervals, for a total of 10 points. The range was recorded, with an average value of 475 HV and a range of 4 HV, yielding austenitic stainless steel with a grade of HV480±5.

[0098] The manufactured stainless steel sheet and strip products were polished with 500#-1000# wet sandpaper. Using a circular sample with a diameter of 2mm, the oxide particles were counted under 100x magnification. There were 7 particles in each unit circle, resulting in austenitic stainless steel with excellent matrix BQ properties.

[0099] A 100mm*500mm sample was taken from the manufactured stainless steel sheet and strip products, and the area of ​​indented particles was calculated under 50x magnification. The incidence of needle-pressing defects was calculated with the defect area as the numerator and the sample area as the denominator. The incidence rate was 13.9%, and austenitic stainless steel with excellent surface quality was obtained.

[0100] Comparative Example 6: The difference from Example 1 is that the shot blasting speed of the black steel coil was 2150 rpm, and the ratio of S110 to S170 shot blasting was 2:2. The transverse and longitudinal hardness of the manufactured stainless steel strip was tested using an electronic micro Vickers hardness tester. Measurements were taken at 20 mm intervals, for a total of 10 points. The range was recorded, with an average value of 477 HV and a range of 3 HV, yielding austenitic stainless steel with a grade of HV480±5.

[0101] The manufactured stainless steel sheet and strip products were polished with 500#-1000# wet sandpaper. Using a circular sample with a diameter of 2mm, the oxide particles were counted under 100x magnification. There were 9 particles in each unit circle, resulting in austenitic stainless steel with excellent matrix BQ properties.

[0102] A 100mm*500mm sample was taken from the manufactured stainless steel sheet and strip products, and the area of ​​indented particles was calculated under 50x magnification. The incidence of needle-pressing defects was calculated with the defect area as the numerator and the sample area as the denominator. The incidence rate was 14.2%, and austenitic stainless steel with excellent surface quality was obtained.

[0103] Comparative Example 7: The difference from Example 3 is that the inner rollers of the cold rolling annealing furnace adopt a single type of roller shape, wherein rollers 1#-3# are made of zero-convex fiber material, and rollers 4#-6# are made of zero-convex ceramic material. The continuous use time of the fiber material rollers is 112 hours, and the continuous use time of the ceramic material rollers is 10.4 hours.

[0104] The transverse and longitudinal hardness of the manufactured stainless steel sheet and strip products were tested using an electronic micro Vickers hardness tester. Measurements were taken at 20mm intervals, for a total of 10 points. The range value was then recorded. The average value was 144 HV and the range was 3 HV, resulting in austenitic stainless steel with a grade of HV150±5.

[0105] The manufactured stainless steel sheet and strip products were polished with 500#-1000# wet sandpaper. Using a circular sample with a diameter of 2mm, the oxide particles were counted under 100x magnification. There were 0 particles in the unit circle, resulting in austenitic stainless steel with excellent matrix BQ properties.

[0106] A 100mm*500mm sample was taken from the manufactured stainless steel sheet and strip products, and the area of ​​indented particles was calculated under 50x magnification. The needle indentation defect rate was calculated with the defect area as the numerator and the sample area as the denominator. The rate was 23.5%, and austenitic stainless steel with excellent surface quality was obtained.

[0107] Comparative Example 8: The difference from Example 3 is that the inner rollers of the cold rolling annealing furnace adopt a composite roller shape, wherein rollers 1#-3# are made of zero-convex fiber material, and rollers 4#-6# are made of 0.1µm convex ceramic material. The fiber material rollers have a continuous service time of 180 hours, and the ceramic material rollers have a continuous service time of 22 hours.

[0108] The transverse and longitudinal hardness of the manufactured stainless steel sheet and strip products were tested using an electronic micro Vickers hardness tester. Measurements were taken at 20mm intervals, for a total of 10 points. The range value was recorded, with an average value of 145 HV and a range of 5 HV, yielding austenitic stainless steel with a grade of HV150±5. The manufactured stainless steel sheet and strip products were polished with 500#-1000# wet sandpaper. Using a circular sample with a diameter of 2mm, the oxide particles were counted under 100x magnification. Zero particles were found within each unit circle, indicating austenitic stainless steel with excellent matrix BQ (bonding quality).

[0109] A 100mm*500mm sample was taken from the manufactured stainless steel sheet and strip products, and the area of ​​indented particles was calculated under 50x magnification. The incidence of needle-pressing defects was calculated with the defect area as the numerator and the sample area as the denominator. The incidence rate was 28.9%, and austenitic stainless steel with excellent surface quality was obtained.

[0110] Results Analysis:

[0111]

[0112]

[0113] Examples 1, 2, 3, 4, and Comparative Examples 1, 2, 4, 5, 6, 7, and 8 demonstrate that the manufacturing method of this invention can stably produce clamp products with a hardness range of 150HV-480HV, covering a wide range of hardness grades to meet the needs of users in different usage environments.

[0114] Comparative Examples 1 and 2 show that when using the smelting and continuous casting process of the present invention to produce steel billets, a settling time of 15-25 minutes and a soft blowing time of 15-30 minutes have a significant effect on controlling the oxide particles in the matrix. Using the technology of the present invention, the number of oxide particles in the matrix per unit area is reduced by 16, a reduction of 89%. It also shows that the settling time has a greater impact on the oxide particles in the matrix than the soft blowing time.

[0115] Comparative Example 3 shows that using the parabolic annealing temperature parameters for black steel coils and the stepped annealing temperature parameters for cold coils of the present invention results in a small difference in hardness between the transverse and longitudinal directions of the strip steel, with the difference decreasing by 8HV, and the hardness becoming uniform and stable.

[0116] Comparative Examples 4, 5, and 6 demonstrate that by employing the shot blasting speed and the shot blasting S110 to S170 ratio of the present invention, the number of oxidized matrix particles per unit area is reduced by 5, a reduction of 63%.

[0117] Comparative Example 7 shows that the composite roller shape of the inner roller in the cold rolling annealing furnace using the present invention reduces the incidence of needle pressure defects by 71% compared with the same period last year, which has a significant effect.

[0118] Comparative Example 8 demonstrates that the composite roller shape used in the cold rolling annealing furnace of this invention significantly improves needle-pressing defects, with fiber material rollers having a continuous service time of ≤120h and ceramic material rollers having a continuous service time of ≤12h. Using the manufacturing technology of this invention, the incidence of needle-pressing defects is reduced by 76% compared to the previous method, demonstrating a significant effect.

[0119] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An austenitic stainless steel for clamps, characterized in that: It comprises the following components by weight percentage: carbon < 0.15%, silicon < 1.00%, manganese 1.00-2.00%, phosphorus < 0.035%, sulfur < 0.003%, chromium 16.00-18.00%, nickel 6.00-8.50%, and other trace elements and iron balance; The above-mentioned method for manufacturing austenitic stainless steel for clamps includes the following steps: S1. After the raw materials pass through the processes of blast furnace molten iron, dephosphorization converter, electric furnace, and AOD furnace, the austenitic stainless steel of the above composition is obtained, and the molten steel is continuously cast into steel billets. S2. The obtained steel billet is subjected to hot rolling, black sheet annealing shot blasting pickling, cold rolling, cold sheet annealing pickling, finishing, secondary rolling, and degreasing cleaning in sequence to obtain austenitic stainless steel for clamps. The cold rolling in step S2 consists of 5%-8% pre-rolling and 50%-60% single rolling; In step S2, the cold rolling annealing and pickling process adopts a stepped annealing temperature of 1000-1190℃. In step S1, the calming time for continuous casting into steel billets is 15-25 minutes, and the soft blowing time is 15-30 minutes. The annealing process of the black steel coil in step S2 adopts a parabolic annealing temperature of 800-1200℃. In step S2, the shot blasting speed is 1800-1900 rpm, and the ratio of shot blasting S110 to S170 is 2:

1.

2. The austenitic stainless steel for clamps according to claim 1, characterized in that: The black leather roll annealing, shot blasting, and pickling process in step S2 includes sulfuric acid pickling and mixed acid pickling. The sulfuric acid concentration is 230~300g / l, the sulfuric acid pickling temperature is 70~80℃, the mixed acid pickling temperature is 45~60℃, the nitric acid concentration is 100~180g / l, and the hydrofluoric acid concentration is 20~50g / l.

3. The austenitic stainless steel for clamps according to claim 1, characterized in that: The cold rolling in step S2 consists of 5%-8% pre-rolling and 50%-60% single rolling; In step S2, the cold rolling annealing and pickling process uses a stepped annealing temperature of 1000-1190℃.

4. The austenitic stainless steel for clamps according to claim 1, characterized in that: The cold rolling annealing pickling in step S2 includes a neutral salt electrolytic pickling process and a mixed acid pickling process; And / or, in the neutral salt electrolytic pickling process, the concentration of sodium sulfate is 100-220 g / l, and the temperature of sodium sulfate is 70-85℃; And / or, the acid pickling temperature is 50~65℃, the nitric acid concentration is 60~120g / l, and the hydrofluoric acid concentration is 5~30g / l.

5. The austenitic stainless steel for clamps according to claim 1, characterized in that: The elongation rate during the finishing process in step S2 is 1%-5%; And / or, the secondary rolling deformation rate in step S2 is 5%-15%; And / or, the degreasing cleaning in step S2 uses an alkaline solution, a cleaning temperature of 80-100℃, and a cleaning speed of 10-20m / min.

6. The austenitic stainless steel for clamps according to claim 1, characterized in that: It also includes step S3: performing transverse and longitudinal hardness tests on the stainless steel sheet and strip products from step S2 to obtain broad-spectrum austenitic stainless steel.

7. The austenitic stainless steel for clamps according to claim 1, characterized in that: For transverse and longitudinal hardness testing, an electronic micro Vickers hardness tester was used to measure the standard sample in both the transverse and longitudinal directions. Measurements were taken at 20mm intervals, for a total of 10 points. The range value was then recorded. If the range value was ≤5HV, the austenitic stainless steel grade HV150-480 was obtained.

8. An austenitic stainless steel for clamps according to claim 6, characterized in that: It also includes step S4: performing microstructure analysis on the stainless steel sheet and strip product from step S2 to obtain austenitic stainless steel with excellent BQ properties. In step S4, a 100mm*500mm sample of stainless steel sheet and strip is taken and the area of ​​indented particles is calculated under 50x magnification. The needle indentation defect rate is calculated with the defect area as the numerator and the sample area as the denominator. If the rate is ≤10%, it is an austenitic stainless steel with excellent surface BQ properties.

9. An austenitic stainless steel for clamps according to claim 8, characterized in that: In step S4, the stainless steel strip product is polished with 500#-1000# wet sandpaper. A circular sample with a diameter of 2mm is taken and the oxide particles are counted under 100x magnification. If there are ≤5 particles in the unit circle, it is an austenitic stainless steel with excellent matrix BQ properties.

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