Method for eliminating rough stripes on surface of duplex stainless steel cold plate

Abstract

The invention discloses a method for eliminating rough stripes on the surface of a duplex stainless steel cold plate, which comprises the following steps: the interval time from the end of cutting of a duplex stainless steel casting blank to the beginning of coping is more than or equal to 48 hours, and the surface temperature of the casting blank before coping is less than or equal to 80 DEG C; the surface of the casting blank is ground for the first time through a 20 # grinding wheel, the opening degree of a screw-down valve of a hydraulic machine ranges from 50% to 70%, the current of a grinding machine ranges from 30 A to 50 A, the stepping of the grinding wheel ranges from 25 mm to 35 mm, and the moving speed of a grinding trolley ranges from 35 m / min to 45 m / min; a 36 # grinding wheel is used for grinding the surface of the casting blank for the second time and the third time, the opening degree of a screw-down valve of the hydraulic machine is 30-50%, the current of the grinding machine is 10-30 A, the stepping of the grinding wheel is 15-25 mm, and the moving speed of the grinding trolley is 25-35 m / min. According to the method, the surface of the casting blank is ground before hot continuous rolling, the surface roughness of the casting blank is reduced, after the ground casting blank is subjected to hot rolling, the thickness of iron and phosphorus on the surface of the plate is basically consistent, the iron and phosphorus can be completely removed after phosphorus removal, macroscopic chromatic aberration is eliminated on the surface of the cold-rolled plate, and therefore rough stripes on the surface of the duplex stainless steel cold plate are eliminated.

Description

Technical Field

[0001] The present invention belongs to the technical field of stainless steel production, and in particular relates to a method for eliminating rough stripes on the surface of a duplex stainless steel cold plate. The method eliminates rough stripes on the surface of the duplex stainless steel cold plate by grinding the surface of the duplex stainless steel ingot before hot continuous rolling. Background Art

[0002] Nitrogen in stainless steel can form and expand the austenite phase, saving or replacing some nickel. Therefore, low-cost duplex stainless steel, which uses nitrogen in place of nickel, has become a research focus within the industry. Duplex stainless steel is increasingly favored by users due to its many advantages, including long service life, high strength, lightweight, excellent weldability, corrosion resistance, and environmental friendliness. Key duplex stainless steel varieties include S32205, S32101, S32750, and S32304, and are widely used in major projects in industries such as defense, aerospace, petrochemicals, shipbuilding, and seawater systems.

[0003] During the production of duplex stainless steel cold plates, rough streaks often appear on the cold plate surface. This defect is directly caused by uneven thickness of iron and phosphorus residues on the surface of the ingot after heating and hot rolling in the hot rolling process. This, combined with incomplete removal of the dephosphorization water, results in inconsistent surface roughness after cold rolling, leading to visible color differences. These defects are typically addressed by adjusting the dephosphorization water pressure during hot rolling and unclogging the dephosphorization water nozzles. However, these methods fail to fundamentally resolve the issue and are generally ineffective. Summary of the Invention

[0004] In order to solve the above technical problems existing in the prior art, the present invention provides a method for eliminating rough stripes on the surface of a duplex stainless steel cold plate. The method eliminates rough stripes on the surface of the duplex stainless steel cold plate by grinding the surface of the duplex stainless steel ingot before hot continuous rolling of the duplex stainless steel ingot, comprising the following steps:

[0005] S1. The interval between the end of cutting and the start of grinding of duplex stainless steel ingots is controlled to be ≥48h, and the surface temperature of duplex stainless steel ingots before grinding is controlled to be ≤80℃;

[0006] S2. First grinding pass: Use a 20# grinding wheel to uniformly grind the surface of the duplex stainless steel ingot for the first time. The hydraulic press that fixes the grinding wheel is set to a 50-70% opening degree of the down-valve, the grinding machine current is controlled to 30-50A, the grinding wheel step is set to 25-35mm, and the grinding trolley moving speed is controlled to 35-45m / min.

[0007] S3, second grinding, using a 36# grinding wheel to uniformly grind the surface of the duplex stainless steel ingot for the second time, wherein the hydraulic press for fixing the grinding wheel is set to a valve opening of 30-50%, the grinding machine current is controlled to 10-30A, the grinding wheel step is set to 15-25mm, and the grinding trolley moving speed is controlled to 25-35m / min;

[0008] S4, the third grinding, using a 36# grinding wheel to perform the third uniform grinding on the surface of the duplex stainless steel ingot, wherein the hydraulic press for fixing the grinding wheel is set to a valve opening of 30-50%, the grinding machine current is controlled to 10-30A, the grinding wheel step is set to 15-25mm, and the grinding trolley moving speed is controlled to 25-35m / min.

[0009] Furthermore, in the above method for eliminating rough streaks on the surface of a duplex stainless steel cold plate, after the implementation of steps S1 to S4, the roughness of the surface of the duplex stainless steel ingot is reduced to ≤60 μm.

[0010] As a specific embodiment, the above method for eliminating rough stripes on the surface of a duplex stainless steel cold plate is applicable to the production of S32205 duplex stainless steel cold plates, wherein the chemical composition of the S32205 duplex stainless steel is as follows by weight: C≤0.03%, Si≤1.0%, Mn≤2.0%, P≤0.030%, S≤0.020%, Cr: 21.0-23.0%, Ni: 4.5-6.5%, Mo: 3.0-3.5%, N: 0.08-0.20%, and the remainder is Fe and unavoidable impurities.

[0011] As another specific embodiment, the above method for eliminating rough stripes on the surface of a duplex stainless steel cold plate is applicable to the production of S32101 duplex stainless steel cold plate, wherein the chemical composition of the S32101 duplex stainless steel is as follows by weight: C≤0.04%, Si≤1.0%, Mn:4.0-6.0%, P≤0.040%, S≤0.030%, Cr:21.0-22.0%, Ni:1.35-1.70%, Mo:0.1-0.8%, Cu:0.1-0.8%, N:0.20-0.25%, and the rest is Fe and unavoidable impurities.

[0012] The method of eliminating rough streaks on the surface of a duplex stainless steel cold plate of the present invention has the following advantages and beneficial effects:

[0013] The present invention is based on the mechanism of generation of rough stripes on the surface of duplex stainless steel cold plate. Grinding is performed on the duplex stainless steel ingot before hot continuous rolling, thereby significantly reducing the roughness of the surface of the duplex stainless steel ingot to 60 μm or less. When the ground duplex stainless steel ingot is heated and hot rolled in a hot continuous rolling process, the surface roughness of the ingot is significantly reduced, so that the thickness of iron and phosphorus on the surface of the hot-rolled plate is basically consistent, and the amount of iron and phosphorus attached to the surface of the hot-rolled plate is small and thin, which can be easily removed after dephosphorization, thereby eliminating the color difference visible to the naked eye on the surface of the duplex stainless steel cold plate obtained by cold rolling, thereby fundamentally eliminating the rough stripe defect on the surface of the duplex stainless steel cold plate, and improving the product quality of the duplex stainless steel cold plate. DETAILED DESCRIPTION

[0014] 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.

[0015] As mentioned above, the rough streaks on the surface of duplex stainless steel cold plate are caused by the uneven thickness of residual iron and phosphorus on the surface of the ingot during hot rolling, resulting in inconsistent surface roughness of the plate after cold rolling, causing color difference visible to the naked eye. To this end, the technical measures of the method for eliminating the rough streaks on the surface of duplex stainless steel cold plate of the present invention are: grinding the surface of the duplex stainless steel ingot before hot rolling of the duplex stainless steel ingot, reducing the roughness of the surface of the duplex stainless steel ingot to Ra≤60μm, so that when the ground duplex stainless steel ingot is heated and hot rolled in the hot rolling process, the surface roughness of the ingot is greatly reduced, making the thickness of iron and phosphorus on the surface of the hot rolled plate basically consistent, and the amount of iron and phosphorus attached to the surface of the hot rolled plate is small and thin, which can be easily removed after dephosphorization, thereby eliminating the color difference visible to the naked eye on the surface of the duplex stainless steel cold plate produced by cold rolling, thereby eliminating the rough streaks on the surface of the duplex stainless steel cold plate from the root, and improving the product quality of the duplex stainless steel cold plate.

[0016] Specifically, the method for eliminating rough stripes on the surface of a duplex stainless steel cold plate of the present invention comprises the following steps:

[0017] S1. The interval between the end of cutting and the start of grinding of duplex stainless steel ingots is controlled to be ≥48h, and the surface temperature of duplex stainless steel ingots before grinding is controlled to be ≤80℃;

[0018] S2. First grinding pass: Use a 20# grinding wheel to uniformly grind the surface of the duplex stainless steel ingot for the first time. The hydraulic press that fixes the grinding wheel is set to a 50-70% opening degree of the down-valve, the grinding machine current is controlled to 30-50A, the grinding wheel step is set to 25-35mm, and the grinding trolley moving speed is controlled to 35-45m / min.

[0019] S3, second grinding, using a 36# grinding wheel to uniformly grind the surface of the duplex stainless steel ingot for the second time, wherein the hydraulic press for fixing the grinding wheel is set to a valve opening of 30-50%, the grinding machine current is controlled to 10-30A, the grinding wheel step is set to 15-25mm, and the grinding trolley moving speed is controlled to 25-35m / min;

[0020] S4, the third grinding, using a 36# grinding wheel to perform the third uniform grinding on the surface of the duplex stainless steel ingot, wherein the hydraulic press for fixing the grinding wheel is set to a valve opening of 30-50%, the grinding machine current is controlled to 10-30A, the grinding wheel step is set to 15-25mm, and the grinding trolley moving speed is controlled to 25-35m / min.

[0021] As a specific embodiment, the method for eliminating rough stripes on the surface of a duplex stainless steel cold plate of the present invention is applicable to the production of S32205 duplex stainless steel cold plates, wherein the chemical composition of the S32205 duplex stainless steel is as follows by weight: C≤0.03%, Si≤1.0%, Mn≤2.0%, P≤0.030%, S≤0.020%, Cr: 21.0-23.0%, Ni: 4.5-6.5%, Mo: 3.0-3.5%, N: 0.08-0.20%, and the remainder is Fe and unavoidable impurities.

[0022] As another specific embodiment, the method for eliminating rough stripes on the surface of a duplex stainless steel cold plate of the present invention is applicable to the production of S32101 duplex stainless steel cold plates, wherein the chemical composition of the S32101 duplex stainless steel is as follows by weight: C≤0.04%, Si≤1.0%, Mn:4.0-6.0%, P≤0.040%, S≤0.030%, Cr:21.0-22.0%, Ni:1.35-1.70%, Mo:0.1-0.8%, Cu:0.1-0.8%, N:0.20-0.25%, and the rest is Fe and unavoidable impurities.

[0023] The method for eliminating rough streaks on the surface of a duplex stainless steel cold plate of the present invention is described in detail below with reference to specific embodiments.

[0024] Example 1

[0025] The steel type involved in Example 1 is S32205 duplex stainless steel. The method for eliminating rough streaks on the surface of a duplex stainless steel cold plate in Example 1 comprises the following steps:

[0026] S1. The interval between the end of cutting and the start of grinding of duplex stainless steel ingot is 62 h, and the surface temperature of duplex stainless steel ingot before grinding is 51 °C.

[0027] S2, first grinding, using a 20# grinding wheel to uniformly grind the surface of the duplex stainless steel ingot for the first time, wherein the hydraulic press for fixing the grinding wheel is pressed down to an opening degree of 61%, the grinding machine current is 43A, the grinding wheel step is 31mm, and the grinding trolley moving speed is 41m / min;

[0028] S3, second grinding, using a 36# grinding wheel to uniformly grind the surface of the duplex stainless steel ingot for the second time, wherein the hydraulic press for fixing the grinding wheel is pressed down to a valve opening of 43%, the grinding machine current is 21A, the grinding wheel step is 18mm, and the grinding trolley moving speed is 27m / min;

[0029] S4, third grinding, repeating the above step S3, and performing a third uniform grinding on the surface of the duplex stainless steel ingot.

[0030] According to actual production conditions, by grinding the surface of the duplex stainless steel ingot using Example 1, the roughness of the surface of the duplex stainless steel ingot was significantly reduced to 50 μm. After heating and hot rolling in the hot rolling process, the thickness of iron and phosphorus on the surface of the hot-rolled plate was basically consistent, and the amount of iron and phosphorus attached to the surface of the hot-rolled plate was small and thin. Therefore, in the subsequent dephosphorization process, the iron and phosphorus on the plate surface were completely removed, thereby eliminating the color difference visible to the naked eye on the surface of the duplex stainless steel cold plate produced after cold rolling, eliminating the rough streak defect on the surface of the duplex stainless steel cold plate from the root, and improving the product quality of the duplex stainless steel cold plate.

[0031] Example 2

[0032] The steel type involved in Example 2 is S32205 duplex stainless steel. The method for eliminating rough streaks on the surface of a duplex stainless steel cold plate in Example 2 comprises the following steps:

[0033] S1. The interval between the end of cutting and the start of grinding of duplex stainless steel ingot is 56 h, and the surface temperature of duplex stainless steel ingot before grinding is 57 °C.

[0034] S2, first grinding, using a 20# grinding wheel to uniformly grind the surface of the duplex stainless steel ingot for the first time, wherein the hydraulic press for fixing the grinding wheel is pressed down to an opening degree of 58%, the grinding machine current is 39A, the grinding wheel step is 28mm, and the grinding trolley moving speed is 38m / min;

[0035] S3, second grinding, using a 36# grinding wheel to uniformly grind the surface of the duplex stainless steel ingot for the second time, wherein the hydraulic press for fixing the grinding wheel is pressed down to a valve opening of 41%, the grinding machine current is 19A, the grinding wheel step is 21mm, and the grinding trolley moving speed is 29m / min;

[0036] S4, third grinding, repeating the above step S3, and performing a third uniform grinding on the surface of the duplex stainless steel ingot.

[0037] According to actual production conditions, by grinding the surface of the duplex stainless steel ingot using Example 2, the roughness of the surface of the duplex stainless steel ingot was significantly reduced to 52 μm. After heating and hot rolling in the hot rolling process, the thickness of iron and phosphorus on the surface of the hot-rolled plate was basically the same, and the amount of iron and phosphorus attached to the surface of the hot-rolled plate was small and thin. Therefore, in the subsequent dephosphorization process, the iron and phosphorus on the plate surface were completely removed, thereby eliminating the color difference visible to the naked eye on the surface of the duplex stainless steel cold plate produced after cold rolling, eliminating the rough streak defect on the surface of the duplex stainless steel cold plate from the root, and improving the product quality of the duplex stainless steel cold plate.

[0038] Example 3

[0039] The steel type involved in Example 3 is S32101 duplex stainless steel. The method for eliminating rough streaks on the surface of a duplex stainless steel cold plate in Example 3 comprises the following steps:

[0040] S1. The interval between the end of cutting and the start of grinding of duplex stainless steel ingot is 91 h, and the surface temperature of duplex stainless steel ingot before grinding is 38 °C.

[0041] S2. First grinding pass: Use a 20# grinding wheel to uniformly grind the surface of the duplex stainless steel ingot for the first time. The hydraulic press for fixing the grinding wheel is pressed down to an opening of 56%, the grinding machine current is 36A, the grinding wheel step is 29mm, and the grinding trolley moves at a speed of 44m / min.

[0042] S3, second grinding, using a 36# grinding wheel to uniformly grind the surface of the duplex stainless steel ingot for the second time, wherein the hydraulic press for fixing the grinding wheel is pressed down to a valve opening of 36%, the grinding machine current is 16A, the grinding wheel step is 22mm, and the grinding trolley moves at a speed of 26m / min;

[0043] S4, third grinding, repeating the above step S3, and performing a third uniform grinding on the surface of the duplex stainless steel ingot.

[0044] According to actual production conditions, by grinding the surface of the duplex stainless steel ingot using Example 3, the surface roughness of the duplex stainless steel ingot was significantly reduced to 55 μm. After heating and hot rolling in the hot rolling process, the thickness of iron and phosphorus on the surface of the hot-rolled plate was basically consistent, and the amount of iron and phosphorus attached to the surface of the hot-rolled plate was small and thin. Therefore, in the subsequent dephosphorization process, the iron and phosphorus on the plate surface were completely removed, thereby eliminating the color difference visible to the naked eye on the surface of the duplex stainless steel cold plate produced after cold rolling, eliminating the rough streak defect on the surface of the duplex stainless steel cold plate from the root, and improving the product quality of the duplex stainless steel cold plate.

[0045] Example 4

[0046] The steel type involved in Example 4 is S32101 duplex stainless steel. The method for eliminating rough streaks on the surface of a duplex stainless steel cold plate in Example 4 comprises the following steps:

[0047] S1. The interval between the end of cutting and the start of grinding of duplex stainless steel ingot is 88 h, and the surface temperature of duplex stainless steel ingot before grinding is 39 °C.

[0048] S2. First grinding pass: Use a 20# grinding wheel to uniformly grind the surface of the duplex stainless steel ingot for the first time. The hydraulic press for fixing the grinding wheel is pressed down to an opening of 52%, the grinding machine current is 40A, the grinding wheel step is 31mm, and the grinding trolley moves at a speed of 41m / min.

[0049] S3, second grinding, using a 36# grinding wheel to uniformly grind the surface of the duplex stainless steel ingot for the second time, wherein the hydraulic press for fixing the grinding wheel is pressed down to a valve opening of 39%, the grinding machine current is 19A, the grinding wheel step is 21mm, and the grinding trolley moving speed is 31m / min;

[0050] S4, third grinding, repeating the above step S3, and performing a third uniform grinding on the surface of the duplex stainless steel ingot.

[0051] According to actual production conditions, by grinding the surface of the duplex stainless steel ingot using Example 4, the roughness of the surface of the duplex stainless steel ingot was significantly reduced to 59 μm. After heating and hot rolling in the hot rolling process, the thickness of iron and phosphorus on the surface of the hot-rolled plate was basically the same, and the amount of iron and phosphorus attached to the surface of the hot-rolled plate was small and thin. Therefore, in the subsequent dephosphorization process, the iron and phosphorus on the plate surface were completely removed, thereby eliminating the color difference visible to the naked eye on the surface of the duplex stainless steel cold plate produced after cold rolling, eliminating the rough streak defect on the surface of the duplex stainless steel cold plate from the root, and improving the product quality of the duplex stainless steel cold plate.

[0052] In summary, the method for eliminating rough stripes on the surface of a duplex stainless steel cold plate of the present invention is based on the generation mechanism of rough stripes on the surface of a duplex stainless steel cold plate. Grinding is performed before hot continuous rolling of the duplex stainless steel ingot, thereby significantly reducing the roughness of the surface of the duplex stainless steel ingot to 60 μm or less. When the ground duplex stainless steel ingot is heated and hot rolled in a hot continuous rolling process, the surface roughness of the ingot is significantly reduced, so that the thickness of iron and phosphorus on the surface of the hot-rolled plate is basically consistent, and the amount of iron and phosphorus attached to the surface of the hot-rolled plate is small and thin, and can be easily removed after dephosphorization, thereby eliminating the color difference visible to the naked eye on the surface of the duplex stainless steel cold plate obtained by cold rolling, thereby fundamentally eliminating the rough stripe defect on the surface of the duplex stainless steel cold plate, and improving the product quality of the duplex stainless steel cold plate.

[0053] It should be noted that, unless otherwise specified, the noun terms herein have the meanings commonly understood by those skilled in the art. Moreover, when a numerical range is disclosed herein, the above range is deemed to be continuous and includes the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple range description features are provided, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0054] It should also be noted that, in this article, the term "comprise" or any other variation thereof is intended to cover non-exclusive inclusion, so that an article or device that includes a series of elements includes not only those elements, but also includes other elements that are not explicitly listed, or also includes elements that are inherent to such article or device.

[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 cause the essence of the corresponding technical solutions to deviate from the scope of the present invention.

Claims

1. A method for eliminating rough streaks on the surface of a duplex stainless steel cold plate, wherein the method comprises grinding the surface of the duplex stainless steel ingot before hot continuous rolling, thereby eliminating rough streaks on the surface of the duplex stainless steel cold plate, wherein: The steps include: S1. The interval between the end of cutting and the start of grinding of duplex stainless steel ingots is controlled to be ≥48h, and the surface temperature of duplex stainless steel ingots before grinding is controlled to be ≤80℃; S2. First grinding pass: Use a 20# grinding wheel to uniformly grind the surface of the duplex stainless steel ingot for the first time. The hydraulic press that fixes the grinding wheel is set to a 50-70% opening degree of the down-valve, the grinding machine current is controlled to 30-50A, the grinding wheel step is set to 25-35mm, and the grinding trolley moving speed is controlled to 35-45m / min. S3, second grinding, using a 36# grinding wheel to uniformly grind the surface of the duplex stainless steel ingot for the second time, wherein the hydraulic press for fixing the grinding wheel is set to a valve opening of 30-50%, the grinding machine current is controlled to 10-30A, the grinding wheel step is set to 15-25mm, and the grinding trolley moving speed is controlled to 25-35m / min; S4, the third grinding, using a 36# grinding wheel to perform the third uniform grinding on the surface of the duplex stainless steel ingot, wherein the hydraulic press for fixing the grinding wheel is set to a valve opening of 30-50%, the grinding machine current is controlled to 10-30A, the grinding wheel step is set to 15-25mm, and the grinding trolley moving speed is controlled to 25-35m / min.

2. The method for eliminating rough streaks on the surface of a duplex stainless steel cold plate according to claim 1, characterized in that: After the implementation of steps S1 to S4, the surface roughness of the duplex stainless steel ingot is reduced to ≤60 μm.

3. The method for eliminating rough streaks on the surface of a duplex stainless steel cold plate according to claim 1, wherein: The method is applicable to the production of S32205 duplex stainless steel cold plates, wherein the chemical composition of the S32205 duplex stainless steel is as follows by weight: C≤0.03%, Si≤1.0%, Mn≤2.0%, P≤0.030%, S≤0.020%, Cr: 21.0-23.0%, Ni: 4.5-6.5%, Mo: 3.0-3.5%, N: 0.08-0.20%, and the remainder is Fe and unavoidable impurities.

4. The method for eliminating rough streaks on the surface of a duplex stainless steel cold plate according to claim 1, wherein: The method is applicable to the production of S32101 duplex stainless steel cold plates, wherein the chemical composition of the S32101 duplex stainless steel is as follows by weight: C≤0.04%, Si≤1.0%, Mn: 4.0-6.0%, P≤0.040%, S≤0.030%, Cr: 21.0-22.0%, Ni: 1.35-1.70%, Mo: 0.1-0.8%, Cu: 0.1-0.8%, N: 0.20-0.25%, and the remainder is Fe and unavoidable impurities.