Production method of martensitic stainless steel TR surface product

Abstract

The invention discloses a production method of a martensitic stainless steel TR surface product, comprising: annealing, leveling, and pickling a hot-rolled martensitic stainless steel coil to form a hot-rolled white coil with a NO.1 surface; rolling the hot-rolled white coil on a rolling mill, controlling the total rolling deformation rate to be 15-40%, controlling the total number of rolling passes to be 3-5, controlling the deformation rate of a single pass to be 4-10%, and controlling the deformation rate of a single pass to decrease pass by pass; using a work roll with a roughness of 0.4-0.6 μm for the first pass, using a work roll with a roughness of 0.1-0.3 μm for the finished product pass, using the work roll for no more than two passes in total, controlling the rolling oil flow rate to be 1500-2000 L / min, and controlling the pressure of the scraper roll to be 60 bar; after the finished product pass is completed, performing an empty pass on the rolling mill at a speed of ≤150 m / min, and padding the steel strip with oil-absorbing paper during the empty pass before winding to form a martensitic stainless steel coil with a TR surface. The mechanical properties and surface quality of the martensitic stainless steel TR surface product produced by the present invention fully meet the use requirements.

Description

Technical Field

[0001] The present invention belongs to the technical field of martensitic stainless steel production, and more particularly relates to a production method of a martensitic stainless steel TR surface product. Background Art

[0002] Martensitic stainless steel is a hardenable stainless steel whose mechanical properties can be adjusted through heat treatment. Major grades include 12Cr13 (SUS410), 20Cr13 (SUS420J1), 30Cr13 (SUS420J2), 40Cr13 (1.4034), and 5Cr15MoV (1.4116). Martensitic stainless steel is primarily used in industries such as knives and scissors, tableware, surgical instruments, and measuring tools.

[0003] Most martensitic stainless steels have a 1D surface, meaning the hot-rolled coils are annealed in a bell furnace, then shot blasted and pickled. The thickness of hot-rolled coils is controlled by hot rolling, with a thickness fluctuation range generally exceeding 0.05mm. Furthermore, due to mechanical shot blasting and pickling, the 1D surface material has a relatively high surface roughness (Ra = 2.5-3.5μm). This requires a high number of surface grinding passes and a high amount of grinding in practical applications such as knife and scissor manufacturing. Furthermore, after bell furnace annealing, the grains of the coils are fully restored, carbides are uniformly precipitated, and the material's hardness is approximately HRB 80-90, which is relatively soft. In practical applications, problems such as sticking to the knife and deformation can easily occur during cutting.

[0004] Currently, demand for martensitic stainless steel materials has gradually shifted to martensitic stainless steel TR surface products. However, the existing technology still lacks an effective martensitic stainless steel TR surface product production process. Generally, the production of martensitic stainless steel TR surface products is based on the production process of other stainless steel TR surface products. Currently, the TR surface materials of other stainless steel grades mostly adopt a double-rolling and degreasing process to ensure surface quality and hardness. This production method generally requires at least four steps: the first cold rolling, annealing and pickling, the second cold rolling, and degreasing. The production cost is high and the production cycle is long. Moreover, the surface quality, hardness, and thickness tolerance of the martensitic stainless steel TR surface products produced by this production method cannot meet the requirements of practical applications.

[0005] Therefore, how to produce martensitic stainless steel TR surface products with surface quality, hardness and thickness tolerance that meet the requirements in a low-cost and short-cycle manner is an urgent problem to be solved in this field. Summary of the Invention

[0006] In order to solve the technical problems existing in the above-mentioned prior art, the present invention provides a method for producing a martensitic stainless steel TR surface product, comprising the following steps:

[0007] Step 1: The martensitic stainless steel hot-rolled coil is annealed, flattened, and pickled to form a hot-rolled white coil with a NO.1 surface;

[0008] Step 2: The hot rolled white coil is rolled on a twenty-roll Sendzimir mill, with the total rolling deformation rate controlled within the range of 15-40%, the total number of rolling passes controlled to be 3-5 passes, the deformation rate of a single pass controlled to be 4-10%, and the deformation rate of a single pass controlled to decrease pass by pass. The first pass uses a work roll with a roughness of 0.4-0.6 μm, and the finished pass uses a work roll with a roughness of 0.1-0.3 μm. The total number of passes using the work roll is controlled to no more than two. During the rolling process, the rolling oil flow rate is controlled to be 1500-2000 L / min, and the scraper roll pressure of the rolling mill is controlled to be 60 bar.

[0009] Step 3: After the finished product pass is completed, the steel strip is passed through an empty pass on the 20-high Sendzimir mill. The steel strip is passed through the mill without pressure from the working rolls. The speed of the empty pass is controlled to be ≤150m / min. During the empty pass, the steel strip is padded with oil-absorbing paper and then coiled to form a martensitic stainless steel coil with a TR surface.

[0010] Furthermore, in the above-mentioned method for producing the TR surface product of martensitic stainless steel, in step 2, after the first pass starts smoothly, both the AFC system and the AGC system are put into use, and the speed of the first pass is controlled at 30-50 m / min.

[0011] Furthermore, in the above-mentioned method for producing the martensitic stainless steel TR surface product, after the finished rolling pass in step 2 is completed and before the idle pass in step 3, the unrolled portion at one end of the hot-rolled white coil is cut off using a disc shear provided on the 20-high Sendzimir mill, and after the idle pass in step 3 is completed, the unrolled portion at the other end of the hot-rolled white coil is cut off using a disc shear.

[0012] Furthermore, in the above-mentioned method for producing the martensitic stainless steel TR surface product, in step 2, both sets of oil scraping rollers of the twenty-high Sendzimir mill are put into use during the rolling process.

[0013] Furthermore, in the above-mentioned method for producing the TR surface product of martensitic stainless steel, in step 3, the specification of the oil-absorbing paper is 38g / m 2 .

[0014] Furthermore, in the above-mentioned production method of the martensitic stainless steel TR surface product, after step 3, n+1 strapping tapes are applied along the axial direction of the martensitic stainless steel coil on the TR surface, and then the product is placed on a packaging unit for packaging, where n is the nominal thickness of the steel strip of the martensitic stainless steel coil on the TR surface, and if n is a decimal, it is rounded up.

[0015] The method for producing the martensitic stainless steel TR surface product of the present invention has the following advantages and beneficial effects:

[0016] (1) The surface roughness of the finished product is Ra ≤ 0.8 μm, and the hardness of the finished product reaches HV220-280. The hardness value of the finished product can be adjusted as needed by changing the rolling deformation rate, fully meeting the actual use requirements;

[0017] (2) The rolling oil residue on the surface of the finished product is very small or even zero, and it can be directly delivered for use without the need for additional degreasing operations using specialized equipment;

[0018] (3) The unrolled sections at the head and tail of the martensitic stainless steel coil on the TR surface are removed during the rolling process, eliminating the need for subsequent removal of the unrolled sections using specialized equipment. This reduces production costs while ensuring material utilization.

[0019] (4) From raw materials to qualified finished products, everything can be completed only on the rolling mill, significantly reducing the production cycle;

[0020] (5) It is suitable for the production of common martensitic stainless steel TR surface products such as 20Cr13, 30Cr13, and 40Cr13. The production range can also be expanded to products with a thickness of 1.5 to 5.8 mm. It is a domestic first and fills the technical gap in the production process of martensitic stainless steel TR surface products. DETAILED DESCRIPTION

[0021] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] According to actual use requirements, the hardness of martensitic stainless steel TR surface products must reach at least HV220-280, the surface roughness must be as low as Ra≤0.8μm, and the surface rolling oil residue must be reduced to a level that allows direct delivery and use without degreasing. The production method of martensitic stainless steel TR surface products provided by the present invention solves the technical problem of the existing technology that cannot produce martensitic stainless steel TR surface products that meet the above requirements, fills the technical gap in the production process of martensitic stainless steel TR surface products, and can be applied to the production of common martensitic stainless steel TR surface products of grades such as 20Cr13, 30Cr13, and 40Cr13. The production range can also be expanded to martensitic stainless steel TR surface products with a raw material thickness of 2.5-6.0mm, a finished product thickness of 1.5-5.8mm, and a product width of 900-1500mm.

[0023] Specifically, the production method of the martensitic stainless steel TR surface product of the present invention comprises the following steps:

[0024] Step 1: The martensitic stainless steel hot-rolled coil is annealed, flattened, and pickled to form a hot-rolled white coil with a NO.1 surface;

[0025] Step 2: The hot rolled white coil is rolled on a twenty-roll Sendzimir mill, with the total rolling deformation rate controlled within the range of 15-40%, the total number of rolling passes controlled to be 3-5 passes, the deformation rate of a single pass controlled to be 4-10%, and the deformation rate of a single pass controlled to decrease pass by pass. The first pass uses a work roll with a roughness of 0.4-0.6 μm, and the finished pass uses a work roll with a roughness of 0.1-0.3 μm. The total number of passes using the work roll is controlled to no more than two. During the rolling process, the rolling oil flow rate is controlled to be 1500-2000 L / min, and the scraper roll pressure of the rolling mill is controlled to be 60 bar.

[0026] Step 3: After the finished product pass is completed, the steel strip is passed through the empty pass on the 20-high Sendzimir mill, that is, the steel strip is passed through the working rolls on the mill without pressure. The speed of the empty pass is controlled to ≤150m / min. During the empty pass, the steel strip is padded with oil-absorbing paper and then coiled to form a martensitic stainless steel coil with a TR surface.

[0027] As a specific implementation method, in step 2, after the first pass starts smoothly, the AFC (automatic plate shape control) system and the AGC (automatic thickness control) system are all put into use to ensure the plate shape level and thickness tolerance. In addition, considering that the raw materials may be unstable during the first pass, the speed of the first pass is controlled at 30 to 50 m / min. Once abnormal plate shape and thickness fluctuations occur, manual adjustments can be made in time.

[0028] As a specific implementation method, after the finished product rolling is completed in step 2, the unrolled portion at one end of the hot-rolled white coil is cut off using the disc shears on the twenty-high Sendzimir rolling mill before the empty pass in step 3; and after the empty pass in step 3 is completed, the unrolled portion at the other end of the hot-rolled white coil is cut off using the disc shears.

[0029] As a specific implementation, in step 2, both sets of oil scraping rollers of the twenty-high Sendzimir mill are put into use during the rolling process to further improve the oil scraping effect.

[0030] As a specific embodiment, in step 3, the specification of the oil-absorbing paper is 38g / m 2 , in order to improve the adsorption effect of grease on the surface of the steel strip.

[0031] As a specific implementation method, after step 3, n+1 strapping strips are applied along the axial direction of the martensitic stainless steel coil on the TR surface, and then the strip is placed on a packaging unit for packaging, where n is the nominal thickness of the strip of the martensitic stainless steel coil on the TR surface, and if n is a decimal, it is rounded up.

[0032] In the production method of the martensitic stainless steel TR surface product of the present invention, by controlling the total rolling deformation rate within the range of 15-40% during the rolling process in step 2, controlling the total rolling passes to 3-5 passes, and controlling the deformation rate of each pass to 4-10%, the hardness of the finished product can reach HV220-280, which fully meets the actual use requirements.

[0033] In the production method of the martensitic stainless steel TR surface product of the present invention, the surface roughness of the hot-rolled white coil of the NO.1 surface formed in step 1 is Ra = 2.5 to 3.5 μm. By using a work roll with a roughness of 0.4 to 0.6 μm in the first pass and a work roll with a roughness of 0.1 to 0.3 μm in the finished pass in step 4, and controlling the total number of passes of the work roll to no more than two, the surface roughness of the steel strip can be made to Ra ≤ 0.8 μm, which fully meets the actual use requirements.

[0034] In the method for producing a martensitic stainless steel TR surface product of the present invention, the process design of controlling the rolling oil flow rate during rolling to 1500-2000 L / min (far lower than the conventional 7000 L / min) and the pressure of the mill scraper roller to 60 bar (higher than the conventional 50 bar) in step 2 significantly reduces surface rolling oil residue and effectively improves the scraping effect. The process design of performing an empty pass on the rolling mill with the work rolls not pressed down while the scraper rollers operate normally in step 3 further improves the scraping effect. The process design of placing oil-absorbing paper on the steel strip in step 3 instead of the recycled paper used in conventional technology improves the adsorption of grease on the steel strip surface. As a result, the residual rolling oil on the product surface can be reduced to a level that allows direct delivery without degreasing, fully meeting actual use requirements.

[0035] The production method of the martensitic stainless steel TR surface product of the present invention can be applied to the production of martensitic stainless steel TR surface products with a raw material thickness of 2.5 to 6.0 mm, a finished product thickness of 1.5 to 5.8 mm, and a product width of 900 to 1500 mm, as shown in Table 1 below.

[0036] Table 1 Thickness of raw materials and finished products of common grades of martensitic stainless steel

[0037]

[0038] The production method of the martensitic stainless steel TR surface product of the present invention is described below with reference to specific embodiments.

[0039] Example 1

[0040] In Example 1 of the present invention, a martensitic hot-rolled steel coil of grade SUS420J2 (30Cr13) was used as raw material. The chemical composition thereof, by mass percentage, was as follows: C: 0.3519%, Si: 0.5730%, Mn: 0.3881%, P: 0.0240%, S: 0.0010%, Cr: 13.3355%, N: 0.0201%, with the remainder being Fe and other unavoidable impurities. The specifications of the martensitic stainless steel hot-rolled steel coil were: thickness: 3.2 mm, width: 1253 mm. The target finished product thickness of the martensitic stainless steel TR surface was 2.5 mm.

[0041] The production method of the martensitic stainless steel TR surface product of Example 1 comprises the following steps:

[0042] Step 1: The raw steel coil is annealed, flattened, and pickled to form a hot-rolled white coil with a surface of No. 1. The actual thickness of the steel strip of the hot-rolled white coil is 3.14 mm, and the surface roughness is Ra = 2.65 μm;

[0043] Step 2: The hot rolled white coil is rolled on a 20-high Sendzimir mill. The total deformation rate is controlled to be 20.38%, and the total number of rolling passes is controlled to be 4. The specific rolling procedures are shown in Table 2 below:

[0044] Table 2 Rolling schedule of Example 1

[0045] path Raw material thickness / mm Finished product thickness / mm Deformation rate 1 3.14 2.92 7.01％ 2 2.92 2.76 5.48％ 3 2.76 2.62 5.07％ 4 2.62 2.50 4.58％

[0046] The first pass uses a working roll with a roughness of 0.5μm. The second pass uses a new roll with a roughness of 0.2μm. The third pass does not use a roll change. The fourth pass uses a new roll with a roughness of 0.2μm. After the first pass starts smoothly, the AFC system and the AGC system are fully put into use to ensure the plate shape level and thickness tolerance. Considering that the raw material may be unstable during the first pass, the speed of the first pass is controlled within 50m / min. Once the plate shape is abnormal or the thickness fluctuates, manual adjustment can be made in time. The scraper roller is checked to ensure that there are no defects such as severe wear on the surface that affect the scraping effect. During the rolling process, the rolling oil flow rate is controlled at 1700L / min. Both sets of scraper rollers are put into use, and the scraper roller pressure is controlled at 60bar to improve the scraping effect. After the fourth pass, the unrolled part of one end of the hot-rolled white skin coil is cut off using the disc shear on the rolling mill.

[0047] Step 3: After the fourth rolling pass is completed, the steel strip is passed through the rolling mill, that is, the steel strip is passed through the rolling mill without pressure on the working rolls. The speed of the pass is controlled to ≤150m / min, and the steel strip is padded with 38g / m 2 The oil-absorbing paper is wound after the hot-rolled white coil is rolled to increase the adsorption effect of surface grease. When the unrolled part at the other end of the hot-rolled white coil runs to the disc shear of the rolling mill, the unrolled part is cut off, and then 4 strapping tapes are applied along the axial direction of the steel coil. Then, the steel coil is put into the packaging unit for packaging to complete the production of martensitic stainless steel coil with TR surface.

[0048] After actual testing, the TR surface product produced by the production method of the martensitic stainless steel TR surface product of Example 1 of the present invention has a finished product hardness of HV260, a surface roughness Ra of 0.6 μm, and zero surface rolling oil residue, which fully meets the actual use requirements.

[0049] In summary, the production method of the martensitic stainless steel TR surface product of the present invention, through the design of the process route, rolling deformation rate, rolling process, roll use, rolling oil parameters, paper padding method, unrolled section removal and other technical measures, produces a martensitic stainless steel TR surface product with mechanical properties and surface quality that fully meet the use requirements. Compared with the prior art, the production method of the martensitic stainless steel TR surface product of the present invention has the following advantages and beneficial effects:

[0050] (1) The surface roughness of the finished product is Ra ≤ 0.8 μm, and the hardness of the finished product reaches HV220-280. The hardness value of the finished product can be adjusted as needed by changing the rolling deformation rate, fully meeting the actual use requirements;

[0051] (2) The rolling oil residue on the surface of the finished product is very small or even zero, and it can be directly delivered for use without the need for additional degreasing operations using specialized equipment;

[0052] (3) The unrolled sections at the head and tail of the martensitic stainless steel coil on the TR surface are removed during the rolling process, eliminating the need for subsequent removal of the unrolled sections using specialized equipment. This reduces production costs while ensuring material utilization.

[0053] (4) From raw materials to qualified finished products, everything can be completed only on the rolling mill, significantly reducing the production cycle;

[0054] (5) It is suitable for the production of common martensitic stainless steel TR surface products such as 20Cr13, 30Cr13, and 40Cr13. The production range can also be expanded to products with a thickness of 1.5 to 5.8 mm. It is a domestic first and fills the technical gap in the production process of martensitic stainless steel TR surface products.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for producing a martensitic stainless steel TR surface product, characterized in that: The steps include: Step 1: The martensitic stainless steel hot-rolled coil is annealed, flattened, and pickled to form a hot-rolled white coil with a NO.1 surface; Step 2: The hot rolled white coil is rolled on a 20-high Sendzimir mill. The total deformation rate of the rolling is controlled within the range of 15-40%, the total number of rolling passes is controlled to be 3-5 passes, the deformation rate of a single pass is controlled to be 4-10%, and the deformation rate of a single pass is controlled to decrease pass by pass. The first pass uses a work roll with a roughness of 0.4-0.6 μm, and the finished pass uses a work roll with a roughness of 0.1-0.3 μm. The total number of passes using the work roll is controlled to no more than two. During the rolling process, the rolling oil flow rate is controlled to be 1500-2000 L / min, and the scraper roll pressure of the rolling mill is controlled to be 60 bar. Step 3: After the finished product pass is completed, the steel strip is passed through the 20-high Sendzimir mill. The steel strip is passed through the mill without pressure from the working rolls. The speed of the pass is controlled to be ≤150m / min. During the pass, the steel strip is covered with oil-absorbing paper and then coiled to form a martensitic stainless steel coil with a TR surface. Among them, after the finished product rolling is completed in step 2 and before the empty pass in step 3, the unrolled part of one end of the hot-rolled white coil is cut off by the disc shear on the twenty-high Sendzimir rolling mill, and after the empty pass in step 3 is completed, the unrolled part of the other end of the hot-rolled white coil is cut off by the disc shear.

2. The method for producing a martensitic stainless steel TR surface product according to claim 1, characterized in that: In step 2, after the first pass starts smoothly, both the AFC system and the AGC system are put into use, and the speed of the first pass is controlled at 30~50m / min.

3. The method for producing a martensitic stainless steel TR surface product according to claim 1, characterized in that: In step 2, both sets of scraper rolls of the twenty-high Sendzimir mill are put into use during the rolling process.

4. The method for producing a martensitic stainless steel TR surface product according to claim 1, characterized in that: In step 3, the specification of the oil absorbing paper is 38g / m 2 .

5. The method for producing a martensitic stainless steel TR surface product according to claim 1, characterized in that: After step 3, n+1 strapping tapes are applied along the axial direction of the martensitic stainless steel coil on the TR surface, and then the coil is placed on a packaging unit for packaging, where n is the nominal thickness of the martensitic stainless steel coil on the TR surface, and if n is a decimal, it is rounded up.

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