阅读说明：本技术 一种2b表面439铁素体不锈钢冷轧方法 (Cold rolling method for 2B surface 439 ferritic stainless steel ) 是由 陈安忠 任娟红 王长波 惠恺 王军伟 李照国 李玉峰 于 2019-10-18 设计创作，主要内容包括：本发明公开了一种2B表面439铁素体不锈钢冷轧方法,属于不锈钢表面处理领域,解决了冷轧2B表面存在白色条状钛条纹缺陷的问题。本发明的技术方案是：热线退火酸洗；冷轧轧机轧制；冷线退火酸洗；在线平整。在冷线退火酸洗步骤中,本发明采用中性盐电解加硝酸电解加低浓度混酸酸洗工艺,通过合理的酸洗方法对退火后带钢进行处理,得到高表面质量要求的冷轧2B表面,本发明方法与传统方法得到的2B表面完全不同,其表面光亮均匀、无白色条状钛条纹缺陷,满足高耐蚀、高表面质量要求装饰面板领域的使用要求；本发明采用低浓度混酸酸洗工艺,可大大降低氮氧化物的排放,减轻环保负担。(The invention discloses a cold rolling method of 439 ferritic stainless steel on a 2B surface, belongs to the field of stainless steel surface treatment, and solves the problem of white strip-shaped titanium stripe defects on the cold-rolled 2B surface. The technical scheme of the invention is as follows: carrying out hot wire annealing and pickling; rolling by a cold rolling mill; cold wire annealing and pickling; and (4) leveling on line. In the step of cold wire annealing and pickling, the invention adopts the pickling process of neutral salt electrolysis, nitric acid electrolysis and low-concentration mixed acid, and the annealed strip steel is treated by a reasonable pickling method to obtain the cold-rolled 2B surface with high surface quality requirement; the invention adopts a low-concentration mixed acid pickling process, can greatly reduce the emission of nitrogen oxides and reduce the burden of environmental protection.)

1. A cold rolling method for a 2B surface 439 ferritic stainless steel is characterized by comprising the following steps:

step one, hot wire annealing and pickling: annealing, sulfuric acid pickling and mixed acid pickling the 439 ferrite stainless steel hot rolled coil to obtain a cold rolled base material;

step two, rolling by a cold rolling mill: rolling the cold-rolled base material obtained in the step one by using a cold-rolling mill to obtain a rolled hard steel coil;

step three, cold wire annealing and pickling: annealing, neutral salt electrolysis, nitric acid electrolysis and mixed acid pickling are carried out on the rolled hard steel coil to obtain the 2D surface 439 ferritic stainless steel coil, and the specific process parameters are as follows:

(1) annealing: the annealing temperature is 900-950 ℃, and the annealing time is 2.0-3.0 min;

(2) neutral salt electrolysis: na with the concentration of 180-220 g/L is adopted₂SO₄The solution is used as electrolyte, the current is 3000-5000A, the temperature is 50-70 ℃, and the electrolysis time is 1.0-2.0 min;

(3) nitric acid electrolysis: the concentration of nitric acid is 100-150 g/l, the current is 2000-4000A, the temperature is 40-60 ℃, and the electrolysis time is 0.1-0.3 min;

(4) mixed acid pickling: the mixed acid is nitric acid and hydrofluoric acid, wherein the concentration of the nitric acid is 100-150 g/l, the concentration of the hydrofluoric acid is 3-8 g/l, the temperature is 30-40 ℃, and the pickling time is 0.2-0.5 min;

step four, online leveling: and e, carrying out online flattening on the 2D surface obtained in the step three, and increasing the surface brightness to obtain the 2B surface 439 ferritic stainless steel coil.

2. The method of claim 1, wherein the cold rolling of the 2B surface 439 ferritic stainless steel comprises: in the first step, the technological parameters of annealing, sulfuric acid pickling and mixed acid pickling are as follows:

(1) annealing: the annealing temperature is 900-1000 ℃, and the annealing time is 2.0-3.0 min;

(2) acid washing with sulfuric acid: the concentration of the sulfuric acid is 250-350 g/L, the temperature of the sulfuric acid is 70-80 ℃, and the pickling time is 0.5-1.5 min;

(3) mixed acid pickling: the mixed acid is nitric acid and hydrofluoric acid, wherein the concentration of the nitric acid is 80-100 g/L, the concentration of the hydrofluoric acid is 15-25 g/L, the temperature of the mixed acid is 40-50 ℃, and the pickling time is 1.5-2.5 min.

3. The method of claim 2B surface 439 ferritic stainless steel cold rolling of claim 2 wherein: and in the second step, rolling for 5-13 times, and controlling the rolling reduction rate to be 50% -87%, so as to obtain the rolled hard steel coil with the final thickness of 0.4-3.0 mm.

4. A 2B surface 439 ferritic stainless steel cold rolling method according to claim 3, characterized in that: in the fourth step, the on-line leveling elongation is 0.3-0.5%.

5. The cold rolling method of a 2B surface 439 ferritic stainless steel according to any of claims 1-4, characterized in that: further comprises the following steps of cutting and packaging: and C, performing split packaging on the 2B surface 439 ferritic stainless steel coil obtained in the step four.

Technical Field

The invention belongs to the field of stainless steel surface treatment, and particularly relates to a cold rolling method of 439 ferrite stainless steel on a 2B surface.

Background

The 439 ferritic stainless steel has excellent corrosion resistance due to the extremely low C, N content and the addition of about 0.3 percent of stabilizing element Ti, and replaces the conventional 304 and 430 steel types in many fields. The 439 steel contains 0.3 percent of Ti, so that the existing cold-rolled 2B surface has white strip-shaped titanium stripe defects, and the defects seriously affect the appearance and severely restrict the use of the 439 steel in the field of decorative panels.

Disclosure of Invention

The invention aims to provide a cold rolling method of a 439 ferritic stainless steel with a 2B surface, which aims to solve the problem that the white strip-shaped titanium stripe defect exists on the cold-rolled 2B surface.

The technical scheme of the invention is as follows: a method of cold rolling a 2B surface 439 ferritic stainless steel comprising the steps of:

step one, hot wire annealing and pickling: annealing, sulfuric acid pickling and mixed acid pickling the 439 ferrite stainless steel hot rolled coil to obtain a cold rolled base material;

step two, rolling by a cold rolling mill: rolling the cold-rolled base material obtained in the step one by using a cold-rolling mill to obtain a rolled hard steel coil;

step three, cold wire annealing and pickling: annealing, electrolyzing neutral salt, electrolyzing nitric acid and pickling with mixed acid on the rolled hard steel coil to obtain a 2D surface 439 ferritic stainless steel coil with a uniform surface and without white strip-shaped titanium stripe defects, wherein the specific process parameters are as follows:

(1) annealing: the annealing temperature is 900-950 ℃, and the annealing time is 2.0-3.0 min;

(2) neutral salt electrolysis: na with the concentration of 180-220 g/L is adopted₂SO₄The solution is used as electrolyte, the current is 3000-5000A, the temperature is 50-70 ℃, and the electrolysis time is 1.0-2.0 min;

(3) nitric acid electrolysis: the concentration of nitric acid is 100-150 g/l, the current is 2000-4000A, the temperature is 40-60 ℃, and the electrolysis time is 0.1-0.3 min;

(4) mixed acid pickling: the mixed acid is nitric acid and hydrofluoric acid, wherein the concentration of the nitric acid is 100-150 g/l, the concentration of the hydrofluoric acid is 3-8 g/l, the temperature is 30-40 ℃, and the pickling time is 0.2-0.5 min;

step four, online leveling: and e, performing online flattening on the 2D surface with the uniform surface and without the white strip-shaped titanium stripe defects obtained in the step three, and increasing the brightness of the surface to obtain a brighter and more uniform 2B surface 439 ferritic stainless steel coil.

As a further improvement of the invention, in the step one, the technological parameters of annealing, sulfuric acid pickling and mixed acid pickling are as follows:

(1) annealing: the annealing temperature is 900-1000 ℃, and the annealing time is 2.0-3.0 min;

(2) acid washing with sulfuric acid: the concentration of the sulfuric acid is 250-350 g/L, the temperature of the sulfuric acid is 70-80 ℃, and the pickling time is 0.5-1.5 min;

(3) mixed acid pickling: the mixed acid is nitric acid and hydrofluoric acid, wherein the concentration of the nitric acid is 80-100 g/L, the concentration of the hydrofluoric acid is 15-25 g/L, the temperature of the mixed acid is 40-50 ℃, and the pickling time is 1.5-2.5 min.

As a further improvement of the invention, in the second step, rolling is carried out for 5-13 times, the rolling reduction is controlled to be 50-87%, and the rolled hard steel coil with the final thickness of 0.4-3.0 mm is obtained.

As a further improvement of the invention, in the fourth step, the elongation of the online leveling is 0.3-0.5%.

As a further improvement of the invention, the method also comprises the following step five of cutting and packaging: and C, performing split packaging on the 2B surface 439 ferritic stainless steel coil obtained in the step four.

The invention provides a new cold rolling method considering the influence of the white strip titanium stripe defect on the surface appearance of the 2B surface, and compared with the traditional method, the method has the following beneficial effects:

1. the traditional 439 ferritic stainless steel cold wire annealing and pickling process adopts a neutral salt electrolysis and mixed acid pickling process, the mixed acid in the process adopts high-concentration acid, the steel contains Ti, the Ti distribution on the surface is uneven, if the high-concentration mixed acid is adopted, selective corrosion occurs, white strip-shaped titanium stripe defects exist on the pickled surface, surface defects such as pickling patterns and the like easily occur, and if the low-concentration mixed acid is adopted, the surface cannot be cleaned completely; the invention adopts the neutral salt electrolysis and nitric acid electrolysis and low-concentration mixed acid pickling process, the step of nitric acid pickling is added in the traditional process, the purpose is to clean the surface, the color difference of the surface is avoided, then the low-concentration mixed acid is used for pickling, the surface cleaning is ensured, and the selective corrosion is avoided;

2. in the cold wire annealing and pickling step, the annealing temperature of the cold-rolled coil is selected to be 900-950 ℃, the annealing temperature is low, the final crystal grains are fine, the grain size is about 7.5 grade, and the cold-rolled coil is free of bending orange peel when used in the decoration field;

3. the invention adopts a low-concentration mixed acid pickling process, can greatly reduce the emission of nitrogen oxides and reduce the burden of environmental protection.

Drawings

FIG. 1 is a surface microstructure of 439 ferritic stainless steel 2B produced by a conventional process;

FIG. 2 is a surface microstructure of 439 ferritic stainless steel 2B produced by the present invention.

Detailed Description

The following examples further illustrate the invention but are not intended to limit the invention in any way.