Method for eliminating surface stripes of duplex stainless steel S32205 cold coil

Abstract

The invention belongs to the field of iron and steel smelting, and relates to a method for eliminating stripes on the surface of a duplex stainless steel S32205 cold coil, which eliminates the stripe defect on the surface of the duplex stainless steel S32205 cold coil, ensures that the cold coil leaves a factory with a high-quality qualified surface, and meets the requirements of special fields. According to the technical scheme, the method comprises the steps that a duplex stainless steel casting blank with the thickness of 160-200 mm is ground, the grinding pressure is adjusted to be minimum, the grinding current is 10-50 A, the advancing speed of a trolley is 10-50 m / min, the surface roughness after grinding is 40-100 microns, and the surface after grinding is free of iron oxide scale residues generated by grinding.

Description

Technical Field

[0001] The invention belongs to the field of steel smelting and relates to a method for eliminating surface stripes of a duplex stainless steel S32205 cold roll. Background Art

[0002] S32205 duplex stainless steel has coexistence of austenite and ferrite in the room temperature structure, and the ratio of the two phases is close to 1:1. This type of steel has outstanding advantages such as high strength (its yield strength is generally twice that of austenitic stainless steel), good resistance to Cl-pitting corrosion, stress corrosion resistance and welding performance. It is widely used in petrochemical, salt making, hydraulic engineering, shipbuilding, civil and other fields.

[0003] S32205 duplex stainless steel has ferrite and austenite structures, and the duplex structures hinder each other, so the grains are fine. At the same time, the steel contains a high content of nitrogen, and its strength is higher than that of ferrite and austenite stainless steel, which can meet the needs of most industries.

[0004] S32205 cold rolled steel coil is widely used in heat exchangers, submarine hoses, cathode plates, etc. due to its good corrosion resistance, high strength and thermal conductivity. Due to its harsh use conditions, it has higher requirements on the surface. Summary of the invention

[0005] In order to overcome the defects in the above-mentioned related technologies, the present invention proposes a method for eliminating the surface stripes of duplex stainless steel S32205 cold coils. The stripe defects on the surface of duplex stainless steel S32205 cold coils are eliminated, ensuring that the cold coils are shipped with high-quality surfaces and meet the requirements of special fields.

[0006] The invention provides a method for eliminating surface stripes of a duplex stainless steel S32205 cold rolled product. The duplex stainless steel S32205 comprises the following components in mass percentage: C≤0.030%, Si≤1.00%, Mn≤2.00%, P≤0.035%, S≤0.020%, Cr: 21.0%-23.0%, Ni: 4.50%-6.50%, Mo: 2.5%-3.5%, N: 0.08%-0.20%, and the rest is Fe and unavoidable impurities.

[0007] The method for eliminating the surface stripes of duplex stainless steel S32205 cold rolled coil comprises: The duplex stainless steel ingot with a thickness of 160-200 mm was ground, the grinding pressure was adjusted to the minimum, the grinding current was 10-50 A, the forward speed of the trolley was 10-50 m / min, the surface roughness after grinding was 40-100 μm, and there was no iron oxide scale residue on the surface after grinding.

[0008] Preferably, the method for eliminating surface stripes of duplex stainless steel S32205 cold coil further comprises applying a layer of descaling water before hot rolling, and the impact force of the descaling water is 0.2 to 2.5 N / cm2.

[0009] Preferably, the method for eliminating surface stripes of duplex stainless steel S32205 cold coil further comprises rebrushing the hot coil before pickling.

[0010] Preferably, the method for eliminating surface stripes of duplex stainless steel S32205 cold rolled steel further comprises 2. using a Na2SO4 electrolytic solution with a concentration of 0.8 to 2.0 g / cm3, an electrolytic current of 1000 to 10000 A, a temperature of 50 to 85°C, and a pickling speed of 5 to 30 m / min.

[0011] The beneficial effects of the present invention are: The invention ensures the corrosion resistance of the material and the appropriate two-phase ratio of the material under solid solution conditions by controlling the key components C, Cr, Ni, Mo and N.

[0012] The invention adopts minimum pressure in the grinding of the ingot to prevent oxidation of the surface of the ingot due to excessive pressure during the grinding process. The grinding current and the forward speed of the trolley adopt relatively small values ​​to ensure that the oxide scale generated on the surface of the ingot during the grinding process is minimal, and to prevent stripes from being generated on the surface of the cold coil due to the oxide scale remaining. The surface roughness of the ingot after grinding ensures the uniformity of the entire surface, and at the same time prevents the surface roughness from being too large and the iron oxide scale from remaining on the rough surface, affecting the surface quality of the cold coil, and preventing stripes from appearing on the surface of the cold coil.

[0013] Before hot rolling, a layer of descaling water is added to remove the oxide scale on the surface of the ingot and the grinding marks, thereby reducing the probability of surface stripes on the cold coil; at the same time, it prevents defects such as iron scale intrusion during hot rolling.

[0014] The hot coil is re-brushed before pickling to remove the iron oxide scale on the surface to avoid the formation of streaks on the cold coil; at the same time, it reduces the surface roughness and increases the surface uniformity.

[0015] Electrolytic sodium sulfate of a certain concentration and temperature can completely remove the oxide scale on the surface without over-electrolysis, thus avoiding the formation of color difference stripe defects on the surface.

[0016] The present invention targets S32205 duplex stainless steel, controls the chemical composition, ingot grinding, hot rolling, hot coil and cold coil pickling and other process links, fine-tunes the duplex ratio, improves the surface quality of the ingot, hot coil and cold coil, and ultimately eliminates the surface stripes of the cold coil. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 The surface of the ingot after grinding by the grinding process; Figure 2 The surface of the cold roll produced by the process of the present invention. DETAILED DESCRIPTION

[0019] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0020] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0021] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more. Example 1

[0022] The invention provides a method for eliminating surface stripes of a duplex stainless steel S32205 cold rolled product. The duplex stainless steel S32205 comprises the following components in percentage by mass: C: 0.015%, Si≤1.00%, Mn≤2.00%, P≤0.035%, S≤0.020%, Cr: 22.5%, Ni: 5.3%, Mo: 3.1%, N: 0.15%, and the rest is Fe and unavoidable impurities.

[0023] The method for eliminating the surface stripes of duplex stainless steel S32205 cold rolled coil comprises: The duplex stainless steel ingot with a thickness of 200 mm was ground. The grinding pressure was adjusted to the minimum, the grinding current was 30 A, the trolley forward speed was 30 m / min, the surface roughness after grinding was 80 μm, and there was no iron oxide scale residue on the surface after grinding.

[0024] Preferably, the method for eliminating surface stripes of duplex stainless steel S32205 cold coil further comprises applying a layer of descaling water before hot rolling, and the impact force of the descaling water is 0.5 N / cm2.

[0025] Preferably, the method for eliminating surface stripes of duplex stainless steel S32205 cold coil further comprises rebrushing the hot coil before pickling.

[0026] Preferably, the method for eliminating surface stripes of duplex stainless steel S32205 cold rolled coil further comprises 2. using a Na2SO4 electrolytic solution with a concentration of 0.8 g / cm3, an electrolytic current of 3000A, a temperature of 50°C, and a pickling speed of 30m / min. Example 2

[0027] The invention provides a method for eliminating surface stripes of a duplex stainless steel S32205 cold rolled product. The duplex stainless steel S32205 comprises the following components in mass percentage: C: 0.010%, Si≤1.00%, Mn≤2.00%, P≤0.035%, S≤0.020%, Cr: 22.8%, Ni: 5.5%, Mo: 3.15%, N: 0.18%, and the rest is Fe and unavoidable impurities.

[0028] The method for eliminating the surface stripes of duplex stainless steel S32205 cold rolled coil comprises: The duplex stainless steel ingot with a thickness of 200 mm was ground. The grinding pressure was adjusted to the minimum, the grinding current was 33 A, the trolley forward speed was 30 m / min, the surface roughness after grinding was 70 μm, and there was no iron oxide scale residue on the surface after grinding.

[0029] Preferably, the method for eliminating surface stripes of duplex stainless steel S32205 cold coil further comprises applying a layer of descaling water before hot rolling, and the impact force of the descaling water is 0.8 N / cm2.

[0030] Preferably, the method for eliminating surface stripes of duplex stainless steel S32205 cold coil further comprises rebrushing the hot coil before pickling.

[0031] Preferably, the method for eliminating surface stripes of duplex stainless steel S32205 cold rolled coil further comprises 2. using a Na2SO4 electrolytic solution with a concentration of 1.0 g / cm3, an electrolytic current of 3500A, a temperature of 65°C, and a pickling speed of 20 m / min.

[0032] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0033] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for eliminating surface stripes of duplex stainless steel S32205 cold rolled coil, characterized in that: The duplex stainless steel S32205 includes the following components in mass percentage: C≤0.030%, Si≤1.00%, Mn≤2.00%, P≤0.035%, S≤0.020%, Cr: 21.0%-23.0%, Ni: 4.50%-6.50%, Mo: 2.5%-3.5%, N: 0.08%-0.20%, and the rest is Fe and unavoidable impurities; The method for eliminating the surface stripes of duplex stainless steel S32205 cold rolled coil comprises: The duplex stainless steel ingot with a thickness of 160-200 mm was ground, the grinding pressure was adjusted to the minimum, the grinding current was 10-50 A, the forward speed of the trolley was 10-50 m / min, the surface roughness after grinding was 40-100 μm, and there was no iron oxide scale residue on the surface after grinding.

2. The method for eliminating surface stripes of duplex stainless steel S32205 cold rolled coil according to claim 1, characterized in that: The method for eliminating the surface stripes of the duplex stainless steel S32205 cold coil also includes applying a layer of descaling water before hot rolling, and the impact force of the descaling water is 0.2 to 2.5 N / cm2.

3. The method for eliminating surface stripes of duplex stainless steel S32205 cold rolled coil according to claim 1, characterized in that: The method for eliminating the surface stripes of the duplex stainless steel S32205 cold coil also includes rebrushing the hot coil before pickling.

4. The method for eliminating surface stripes of duplex stainless steel S32205 cold rolled coil according to claim 1, characterized in that: The method for eliminating surface stripes of duplex stainless steel S32205 cold coil also includes 2. using a Na2SO4 electrolytic solution with a concentration of 0.8 to 2.0 g / cm3, an electrolytic current of 1000 to 10000A, a temperature of 50 to 85°C, and a pickling speed of 5 to 30 m / min.

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