Cold rolling production method of ferritic stainless steel tes18 for elevator trim panel

Abstract

The application discloses a cold-rolling production method of ferritic stainless steel TES18 for elevator decorative panels, which comprises the following steps: after annealing, skinning and pickling, a hot-rolled white skin coil with NO.1 surface is formed by ferritic stainless steel hot-rolled steel coil; the hot-rolled white skin coil is rolled by a five-stand rolling mill; the surface after rolling is continuously annealed and pickled, the annealing temperature is 890-900 DEG C, and the furnace holding time is 60-80 seconds / mm; the surface after annealing is pickled by electrolytic sodium sulfate+electrolytic nitric acid; the steel coil is on-line skinned on a cold-rolling pickling line after annealing and pickling, the convexity of the skinning roller is 20, the tension is 6-7 tons, and the skinning pressure is 200-240 tons; and the steel coil is off-line skinned after on-line skinning, the convexity of the skinning roller is 20, the tension is 6-7 tons, and the skinning pressure is 200-480 tons. The cold-rolling production method can produce ferritic stainless steel products for elevator decorative panels with good and stable performance, and fully meets the processing performance requirements and the aesthetic performance requirements of the elevator decorative panels.

Description

Technical Field

[0001] This invention belongs to the field of ferritic stainless steel production technology, and more specifically relates to a cold rolling production method of ferritic stainless steel TES18 for elevator decorative panels. Background Technology

[0002] Ferritic stainless steel products used in elevator decorative panels need to meet both processing performance and aesthetic performance requirements. Specifically, the processing performance indicators for ferritic stainless steel products used in elevator decorative panels include: yield strength ≤ 320MPa, tensile strength ≤ 500MPa, and hardness HRB ≤ 75; the aesthetic performance indicators include: surface roughness Ra ≤ 0.15μm and grain size > 6.

[0003] Taiyuan Iron & Steel Group's TES18 ferritic stainless steel, used for elevator decorative panels, is employed as a high-end material for elevator car interiors. This product not only meets the performance requirements of elevator panels but also aligns with low-carbon, environmentally friendly, and economical standards, injecting new energy into the future development of the elevator industry. The TES18 ferritic stainless steel is a medium-chromium ferritic stainless steel with the following chemical composition by mass percentage: C: 0.025%~0.050%, Si: 0.20%~0.50%, Mn: 0.20%~0.60%, P≤0.040%, S≤0.010%, Cr: 18.0%~19.5%, Ni: 0.10%~0.40%, Mo: 0.10%~0.50%, N: 0.030%~0.050%, Cu: 0.10%~0.50%, with the balance being Fe and unavoidable impurities.

[0004] However, because TES18 has a higher carbon content than conventional elevator steel, resulting in higher strength, elevator manufacturers may experience performance mismatches when processing it using existing equipment and production processes. Furthermore, the addition of Mo and Mn elements to TES18 results in a dense iron scale on the product surface, making it difficult to pickle and prone to defects such as incomplete cleaning. Although increasing the mixed acid concentration and using a secondary brush can improve efficiency, increasing the mixed acid concentration only improves the pickling success rate and still easily leads to defects such as black flakes. Moreover, hydrofluoric acid is expensive, increasing costs rather than decreasing them. Using a secondary brush, while providing a more uniform surface finish compared to ordinary brush rollers, does not significantly improve speed.

[0005] Therefore, conventional elevator steel in existing technologies generally suffers from large springback during processing and an "orange peel" finish at bends due to their manufacturing processes. This results in product quality that fails to meet the processing performance and aesthetic requirements of ferritic stainless steel for elevator decorative panels. Furthermore, for ferritic stainless steel TES18, which meets the requirements for high-end elevator panels, there is a lack of effective and reliable manufacturing processes to enable its widespread production and application, thus hindering the development of the elevator industry. Summary of the Invention

[0006] To address the technical problems existing in the prior art, this invention provides a cold-rolling production method for ferritic stainless steel TES18 used in elevator decorative panels. The chemical composition of the ferritic stainless steel TES18, by mass percentage, is: C: 0.025%~0.050%, Si: 0.20%~0.50%, Mn: 0.20%~0.60%, P≤0.040%, S≤0.010%, Cr: 18.0%~19.5%, Ni: 0.10%~0.40%, Mo: 0.10%~0.50%, N: 0.030%~0.050%, Cu: 0.10%~0.50%, with the balance being Fe and unavoidable impurities. The cold-rolling production method for the ferritic stainless steel TES18 used in elevator decorative panels includes the following steps: Step 1: After annealing, leveling and pickling, the hot-rolled ferritic stainless steel TES18 coil is formed into a hot-rolled white sheet coil with surface NO.1. The surface roughness of the hot-rolled white sheet coil is controlled to Ra=2.5~3.5μm. Step 2: The hot-rolled white sheet coil is rolled on a five-stand rolling mill. The total rolling deformation rate is controlled according to Table 1, and the roughness of the work rolls used in each stand of the five-stand rolling mill is allocated according to Table 2. Table 1 ; Table 2 ; Step 3: The surface after rolling is subjected to continuous annealing and pickling. During the annealing process, the annealing temperature is controlled at 890~900℃, and the holding time in the annealing furnace is controlled at 60~80 seconds / mm. After annealing, the surface is pickled by electrolytic sodium sulfate + electrolytic nitric acid. At the pickling outlet, a brush roller made of silicon carbide is used to brush the surface of the steel strip. Step 4: The annealed and pickled steel coils are leveled online on the cold rolling pickling line. During the online leveling process, the crown of the leveling rollers is controlled at 20, the tension is set at 6~7 tons, and the leveling pressure is set at 200~240 tons. Step 5: Perform offline leveling on the steel coil after online leveling. During the offline leveling process, the crown of the leveling roller is controlled at 20, the tension is set at 6~7 tons, and the leveling pressure is set at 200~480 tons.

[0007] In one embodiment, the above-described cold rolling production method of ferritic stainless steel TES18 for elevator decorative panels of the present invention is used to produce ferritic stainless steel TES18 products for elevator car decorative panels with a raw material thickness of 3.0~5.0mm, a finished product thickness of 0.6~2.0mm, and a width of 1000~1300mm.

[0008] Furthermore, in the above-mentioned cold-rolled production method of ferritic stainless steel TES18 for elevator decorative panels, the specifications of the hot-rolled ferritic stainless steel TES18 coil are: thickness 4.0 mm, width 1253 mm, and the finished thickness of the target product is 1.2 mm, and: In step 1, the surface roughness of the hot-rolled white sheet is Ra = 3.24 μm; In step 2, the surface roughness of the work rolls used in each stand of the five-stand rolling mill is allocated according to Table 3; Table 3 ; In step 3, the annealing temperature is controlled at 895℃, and the holding time in the annealing furnace is controlled at 74 seconds / mm. After the high-temperature holding is completed, rapid cooling is performed using mist cooling + air cooling. The steel strip is then removed from the furnace after cooling to below 120℃. During pickling with electrolytic sodium sulfate + electrolytic nitric acid, the sodium sulfate concentration is 1.12 g / cm³. 3 The electrolysis current is 4000A and the temperature is 80℃. The nitric acid concentration is 162g / L and the electrolysis current is 2500A and the temperature is 40℃. Silicon carbide brush rollers are used to clean the surface of the steel strip at the outlet of the sodium sulfate electrolysis tank and the outlet of the nitric acid electrolysis tank, respectively. In step 4, the tension during the online leveling process is set to 6 tons, the leveling pressure is set to 220 tons, and the leveling elongation rate is 0.32%. In step 5, the tension during the offline leveling process is set to 6 tons, the leveling pressure is set to 260 tons, and the leveling elongation rate is 0.4%.

[0009] The cold-rolling production method of ferritic stainless steel TES18 for elevator decorative panels provided by this invention, through control of rolling deformation rate, rolling work roll roughness distribution, annealing and pickling process parameters, and online and offline leveling process parameters, can produce ferritic stainless steel products for elevator decorative panels with good performance and stable forming, fully meeting the processing performance and aesthetic performance requirements of elevator decorative panels. Compared with the prior art, the cold-rolling production method of ferritic stainless steel TES18 for elevator decorative panels of this invention has the following advantages and beneficial effects: (1) The finished material has a yield strength ≤320MPa, tensile strength ≤500MPa, hardness HRB≤75, surface roughness Ra≤0.15μm, and grain size >6, which fully meets the processing performance requirements and aesthetic performance requirements of ferritic stainless steel products used for elevator decorative panels. (2) Effectively eliminates the defects of large processing springback and "orange peel" at the bending point that are common in the existing technology, significantly improves product quality, and fully meets the usage needs of the high-end elevator decorative panel industry; (3) The production range can be expanded to ferritic stainless steel products for elevator car decorative panels with raw material thickness of 3.0~5.0mm, finished product thickness of 0.6~2.0mm and width of 1000~1300mm. It perfectly solves the problem of large-scale production and application of ferritic stainless steel TES18 to meet the needs of the high-end elevator decorative panel industry. It is the first of its kind in China and fills the technical gap in the production process of ferritic stainless steel TES18 for elevator decorative panels. Detailed Implementation

[0010] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0011] The cold rolling production method of ferritic stainless steel TES18 for elevator decorative panels of the present invention includes the following steps: Step 1: After annealing, leveling and pickling, the hot-rolled ferritic stainless steel TES18 coil is formed into a hot-rolled white sheet coil with surface NO.1. The surface roughness of the hot-rolled white sheet coil is controlled to Ra=2.5~3.5μm. Step 2: The hot-rolled white sheet coil is rolled on a five-stand rolling mill. The total rolling deformation rate is controlled according to Table 1 below, and the roughness of the work rolls used in each stand of the five-stand rolling mill is allocated according to Table 2 below. Table 1 Total Rolling Deformation Rate (Correspondence Table of Raw Material Thickness and Finished Product Thickness) ; Table 2. Roughness of work rolls on each stand of the five-stand rolling mill ; Step 3: The surface after rolling is continuously annealed and pickled. In order to ensure the strength of the material, the annealing temperature is controlled at 890~900℃ and the holding time in the annealing furnace is controlled at 60~80 seconds / mm. After annealing, the surface is pickled by electrolytic sodium sulfate + electrolytic nitric acid. At the pickling outlet, a brush roller made of silicon carbide is used to brush the surface of the steel strip. Step 4: The annealed and pickled steel coils are leveled online on the cold rolling pickling line. To ensure the required yield strength of the material, the crown of the leveling roller used in the online leveling process is controlled at 20, that is, the diameter of the middle of the leveling roller is 0.2mm higher than the diameter of the two ends of the leveling roller. The tension is set to 6~7 tons and the leveling pressure is set to 200~240 tons. Step 5: After online leveling, the steel coil is leveled offline. To improve the surface roughness and shape of the steel strip, the crown of the leveling roller used in the offline leveling process is controlled at 20, that is, the middle diameter of the leveling roller protrudes 0.2mm higher than the diameters at both ends of the leveling roller. The tension is set to 6~7 tons and the leveling pressure is set to 200~480 tons.

[0012] In the cold rolling production method of ferritic stainless steel TES18 for elevator decorative panels of the present invention, by controlling the total rolling deformation rate and distributing the roughness of the work rolls of each stand in step 2, the surface roughness of the ferritic stainless steel strip can reach Ra≤0.15μm.

[0013] In the cold rolling production method of ferritic stainless steel TES18 for elevator decorative panels of the present invention, by adopting annealing process parameters of annealing temperature of 890~900℃ and furnace holding time of 60~80 seconds / mm in step 3, the grain size of ferritic stainless steel material can be >6.

[0014] In the cold rolling production method of ferritic stainless steel TES18 for elevator decorative panels of the present invention, the ferritic stainless steel strip can be cleaned by pickling in step 3 using electrolytic sodium sulfate + electrolytic nitric acid and brushing the surface of the steel strip with a silicon carbide brush roller at the pickling outlet.

[0015] In the cold rolling production method of ferritic stainless steel TES18 for elevator decorative panels of the present invention, by using online leveling process parameters of 20mm flatness, 6-7 tons tension, and 200-240 tons leveling pressure in step 4, and offline leveling process parameters of 20mm flatness, 6-7 tons tension, and 200-240 tons leveling pressure in step 5, the ferritic stainless steel strip can be made to have a straight strip shape, and the yield strength of the ferritic stainless steel material is ≤320MPa, tensile strength is ≤500MPa, and hardness is HRB≤75.

[0016] As one specific embodiment, the cold rolling production method of ferritic stainless steel TES18 for elevator decorative panels of the present invention is applicable to the production of ferritic stainless steel TES18 products with a raw material thickness of 3.0~5.0mm, a finished product thickness of 0.6~2.0mm, and a width of 1000~1300mm, for use as elevator car decorative panels.

[0017] The following describes the cold rolling production method of ferritic stainless steel TES18 for elevator decorative panels according to the present invention with reference to specific embodiments.

[0018] Example 1 In Embodiment 1 of this invention, medium chromium ferritic stainless steel TES18 hot-rolled steel coil is used as raw material. The specifications of the ferritic stainless steel TES18 hot-rolled steel coil are: thickness 4.0mm and width 1253mm. The finished thickness of the ferritic stainless steel target product used for elevator decorative panels is 1.2mm.

[0019] The cold rolling production method of ferritic stainless steel TES18 for elevator decorative panels in Example 1 includes the following steps: Step 1: After annealing, leveling and pickling, TES18 steel coils are formed into hot-rolled white coils with NO.1 surface. The surface roughness of the hot-rolled white coils is Ra=3.24μm. The specific production process will not be described in detail here. Step 2: The hot-rolled white sheet coil is rolled on a five-stand rolling mill. Based on the raw material thickness of 4.0 mm and the finished product thickness of 1.2 mm, the total rolling deformation rate is determined to be 70.00%. The roughness of the work rolls used in each stand of the five-stand rolling mill is allocated according to Table 3 below. Table 3. Roughness of work rolls on each stand of the five-stand rolling mill ; Step 3: The rolled surface undergoes continuous annealing and pickling. To ensure material strength, the annealing temperature is controlled at 895℃, and the holding time in the annealing furnace is controlled at 74 seconds / mm. After the high-temperature holding period, rapid cooling is performed using a combination of mist cooling and air cooling. The steel strip is removed from the furnace after cooling to below 120℃. After annealing, the surface is pickled using electrolytic sodium sulfate and electrolytic nitric acid, with a sodium sulfate concentration of 1.12 g / cm³. 3 The electrolysis current is 4000A, the temperature is 80℃, the nitric acid concentration is 162g / L, the electrolysis current is 2500A, and the temperature is 40℃. At the outlet of the sodium sulfate electrolysis tank and the outlet of the nitric acid electrolysis tank, respectively, the steel strip surface is brushed with brush rollers made of silicon carbide. Step 4: The annealed and pickled steel coils are leveled online on the cold rolling pickling line. To ensure the required yield strength of the material, the crown of the leveling rollers used in the online leveling process is controlled at 20, that is, the diameter of the middle of the leveling roller is 0.2mm higher than the diameters of the two ends of the leveling roller. The tension is set to 6 tons, the leveling pressure is set to 220 tons, and the leveling elongation is 0.32%. Step 5: After online leveling, the steel coil is leveled offline. To improve the surface roughness and shape of the steel strip, the crown of the leveling roller used in the offline leveling process is controlled at 20, that is, the middle diameter of the leveling roller protrudes 0.2mm higher than the diameters at both ends of the leveling roller. The tension is set to 6 tons, the leveling pressure is set to 260 tons, and the leveling elongation rate is 0.4%.

[0020] Then, the flattened steel coil is cut clean of the defective parts at the beginning and end on the slitting unit, and then packaged to complete the cold rolling production of ferritic stainless steel TES18 for elevator decorative panels.

[0021] The ferritic stainless steel TES18 product for elevator decorative panels, produced using the cold rolling method of Example 1, was tested. Its yield strength was 311 MPa, tensile strength was 478 MPa, hardness HRB was 73.5, elongation was 32%, surface roughness Ra was 0.11 μm, and grain size was grade 7. This fully meets the processing performance requirements for ferritic stainless steel products used in elevator decorative panels, which include a yield strength ≤320 MPa, tensile strength ≤500 MPa, and hardness HRB ≤75, as well as the aesthetic performance requirements of a surface roughness Ra ≤0.15 μm and grain size >6.

[0022] In summary, the cold-rolling production method of ferritic stainless steel TES18 for elevator decorative panels provided by this invention, through control of rolling deformation rate, distribution of rolling work roll roughness, control of annealing and pickling process parameters, and control of online and offline leveling process parameters, can produce ferritic stainless steel products for elevator decorative panels with good performance and stable forming, fully meeting the processing performance and aesthetic performance requirements of elevator decorative panels. Compared with the prior art, the cold-rolling production method of ferritic stainless steel TES18 for elevator decorative panels of this invention has the following advantages and beneficial effects: (1) The finished material has a yield strength ≤320MPa, tensile strength ≤500MPa, hardness HRB≤75, surface roughness Ra≤0.15μm, and grain size >6, which fully meets the processing performance requirements and aesthetic performance requirements of ferritic stainless steel products used for elevator decorative panels. (2) Effectively eliminates the defects of large processing springback and "orange peel" at the bending point that are common in the existing technology, significantly improves product quality, and fully meets the usage needs of the high-end elevator decorative panel industry; (3) The production range can be expanded to ferritic stainless steel products for elevator car decorative panels with raw material thickness of 3.0~5.0mm, finished product thickness of 0.6~2.0mm and width of 1000~1300mm. It perfectly solves the problem of large-scale production and application of ferritic stainless steel TES18 to meet the needs of the high-end elevator decorative panel industry. It is the first of its kind in China and fills the technical gap in the production process of ferritic stainless steel TES18 for elevator decorative panels.

[0023] It should be noted that, in this document, the term "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device.

[0024] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A cold-rolling production method for ferritic stainless steel TES18 used in elevator decorative panels, characterized in that, The chemical composition of the ferritic stainless steel TES18, by mass percentage, is as follows: C: 0.025%~0.050%, Si: 0.20%~0.50%, Mn: 0.20%~0.60%, P≤0.040%, S≤0.010%, Cr: 18.0%~19.5%, Ni: 0.10%~0.40%, Mo: 0.10%~0.50%, N: 0.030%~0.050%, Cu: 0.10%~0.50%, with the balance being Fe and unavoidable impurities. It is used to produce ferritic stainless steel TES18 products for elevator car decorative panels with a raw material thickness of 3.0~5.0 mm, a finished product thickness of 0.6~2.0 mm, and a width of 1000~1300 mm. The cold-rolling production method of the ferritic stainless steel TES18 for elevator decorative panels includes the following steps: Step 1: After annealing, leveling and pickling, the hot-rolled ferritic stainless steel TES18 coil is formed into a hot-rolled white sheet coil with surface NO.

1. The surface roughness of the hot-rolled white sheet coil is controlled to Ra=2.5~3.5μm. Step 2: The hot-rolled white coil is rolled on a five-roll mill. When the nominal thickness of the raw material is 3mm, the nominal thickness of the finished product is 0.6~0.8mm; when the nominal thickness of the raw material is 3.5mm, the nominal thickness of the finished product is 1mm; when the nominal thickness of the raw material is 4mm, the nominal thickness of the finished product is 1.2mm; when the nominal thickness of the raw material is 4.5mm, the nominal thickness of the finished product is 1.5mm; and when the nominal thickness of the raw material is 5mm, the nominal thickness of the finished product is 2mm. The surface roughness distribution of the work rolls used in each stand of the five-stand rolling mill is as follows: the surface roughness of work roll #1 is 1.2~1.5μm, the surface roughness of work roll #2 is 1.0~1.2μm, the surface roughness of work roll #3 is 0.6~0.8μm, the surface roughness of work roll #4 is 0.3~0.4μm, and the surface roughness of work roll #5 is 0.12~0.15μm; Step 3: The surface after rolling is subjected to continuous annealing and pickling. During the annealing process, the annealing temperature is controlled at 890~900℃, and the holding time in the annealing furnace is controlled at 60~80 seconds / mm; After annealing, the surface is pickled by electrolytic sodium sulfate + electrolytic nitric acid. At the pickling exit, a brush roller made of silicon carbide is used to brush the surface of the steel strip; Step 4: The annealed and pickled steel coils are leveled online on the cold rolling pickling line. During the online leveling process, the crown of the leveling rollers is controlled at 20, the tension is set at 6~7 tons, and the leveling pressure is set at 200~240 tons. Step 5: After online leveling, the steel coil is leveled offline. During the offline leveling process, the crown of the leveling roller is controlled at 20, the tension is set at 6~7 tons, and the leveling pressure is set at 200~480 tons. The finished product has a yield strength ≤320MPa, tensile strength ≤500MPa, HRB≤75, surface roughness Ra≤0.15μm, and grain size >6.

2. The cold rolling production method of ferritic stainless steel TES18 for elevator decorative panels according to claim 1, characterized in that, The specifications of the ferritic stainless steel TES18 hot-rolled coil are: thickness 4.0mm, width 1253mm, and the finished thickness of the target product is 1.2mm, and: In step 1, the surface roughness of the hot-rolled white sheet is Ra = 3.24 μm; In step 2, the surface roughness of the work rolls used in each stand of the five-stand rolling mill is distributed as follows: the surface roughness of work roll #1 of stand is 1.4 μm, the surface roughness of work roll #2 of stand is 1.2 μm, the surface roughness of work roll #3 of stand is 0.8 μm, the surface roughness of work roll #4 of stand is 0.4 μm, and the surface roughness of work roll #5 of stand is 0.14 μm. In step 3, the annealing temperature is controlled at 895℃, and the holding time in the annealing furnace is controlled at 74 seconds / mm. After the high-temperature holding is completed, rapid cooling is performed using mist cooling + air cooling. The steel strip is then removed from the furnace after cooling to below 120℃. During pickling with electrolytic sodium sulfate + electrolytic nitric acid, the sodium sulfate concentration is 1.12 g / cm³. 3 The electrolysis current is 4000A and the temperature is 80℃. The nitric acid concentration is 162g / L and the electrolysis current is 2500A and the temperature is 40℃. Silicon carbide brush rollers are used to clean the surface of the steel strip at the outlet of the sodium sulfate electrolysis tank and the outlet of the nitric acid electrolysis tank, respectively. In step 4, the tension during the online leveling process is set to 6 tons, the leveling pressure is set to 220 tons, and the leveling elongation rate is 0.32%. In step 5, the tension during the offline leveling process is set to 6 tons, the leveling pressure is set to 260 tons, and the leveling elongation rate is 0.4%.