阅读说明：本技术 一种改善含钛铁素体不锈钢表面起皱缺陷的方法 (Method for improving surface wrinkling defect of titanium-containing ferrite stainless steel ) 是由 蒲嘉亮 徐向东 方剑锋 文健 于 2021-06-18 设计创作，主要内容包括：本发明涉及一种改善含钛铁素体不锈钢表面起皱缺陷的方法,对热轧产出的黑皮钢卷进行退火,退火温度950±20℃,退火时间80～160s；对退火钢卷经行硫酸酸洗,再经过硝酸+氢氟酸酸洗；冷轧采用单机架二十辊可逆式冷轧机组进行5～9道次轧制,经连续退火,再置入硫酸钠中性盐溶液中进行电解,置入硝酸和氢氟酸混合溶液中酸洗,由张力整平机进行张力整平,使用调制轧延机轧延得到最终产品。优点是：采用本发明方法能将含钛铁素体不锈钢表面起皱的缺陷控制在轻微程度,能有效降低制品打磨的成本,提高生产效率。(The invention relates to a method for improving the surface wrinkling defect of titanium-containing ferrite stainless steel, which is characterized in that a black strip coil produced by hot rolling is annealed at the annealing temperature of 950 +/-20 ℃ for 80-160 s; pickling the annealed steel coil by sulfuric acid, and pickling by nitric acid and hydrofluoric acid; and (3) carrying out cold rolling for 5-9 times by adopting a single-frame twenty-roller reversible cold rolling unit, continuously annealing, electrolyzing in a sodium sulfate neutral salt solution, pickling in a nitric acid and hydrofluoric acid mixed solution, carrying out tension leveling by using a tension leveling machine, and rolling by using a modulation rolling mill to obtain a final product. The advantages are that: the method can control the wrinkle defect of the surface of the titanium-containing ferrite stainless steel to a slight degree, effectively reduce the polishing cost of products and improve the production efficiency.)

1. A method for improving the surface wrinkling defects of titanium-containing ferritic stainless steel is characterized by comprising the following steps:

1) annealing the black strip steel coil produced by hot rolling at the annealing temperature of 950 +/-20 ℃ for 80-160 s to ensure that core grains are completely grown and no banded structure residue exists;

pickling the annealed steel coil by sulfuric acid, and pickling by nitric acid and hydrofluoric acid to obtain a hot-rolled, annealed and pickled stainless steel plate strip;

2) carrying out cold rolling for 5-9 times by adopting a single-frame twenty-roller reversible cold rolling unit to obtain a cold-rolled stainless steel plate strip; continuously annealing the cold-rolled stainless steel plate strip at 950 +/-50 ℃ for 120 +/-30 s to obtain the cold-rolled annealed stainless steel plate strip; placing the stainless steel plate strip subjected to cold rolling annealing into a sodium sulfate neutral salt solution for electrolysis to obtain a stainless steel plate strip subjected to cold rolling annealing electrolysis, and then placing the stainless steel plate strip into a mixed solution of nitric acid and hydrofluoric acid for pickling to obtain a stainless steel plate strip subjected to cold rolling, complete annealing and pickling; and (3) carrying out tension leveling on the obtained stainless steel plate belt by using a tension leveling machine, wherein the elongation is less than or equal to 0.30%, and rolling by using a modulation rolling mill to obtain a final product.

2. The method for improving the surface wrinkling defect of the titanium-containing ferritic stainless steel according to the claim 1, characterized in that the method for producing the black strip steel coil produced by the hot rolling in the step 1) comprises the following steps:

1) when molten steel is cast, strong electromagnetic stirring is applied in a secondary cooling stage, and the proportion of medium axial crystals in a casting blank is not lower than 50% at a current of 1000-2000A;

2) feeding the casting blank into a heating furnace for heating, controlling the tapping temperature at 1100-1200 ℃, and keeping the time in the furnace for 3-4 h; the hot rolling and rough rolling adopt 5-7 times of rolling to obtain a middle-thickness plate blank with the thickness of 30-40 mm; and (3) carrying out finish rolling by adopting a tandem type 7-station rolling way to obtain the black-skin steel coil with the thickness of 2.0-10.0 mm.

3. The method for improving surface wrinkling defects of titanium-containing ferritic stainless steel sheet according to claim 1 wherein said tension leveler uses a non-chrome plated roller.

Technical Field

The invention belongs to the field of stainless steel production, and particularly relates to a method for improving the surface wrinkling defect of titanium-containing ferritic stainless steel.

Background

The 400 series titanium-containing stainless steel is an important branch of stainless steel, and is more and more favored by the market due to good intergranular corrosion resistance and excellent welding performance, wherein 409L is taken as a representative steel grade of the titanium-containing stainless steel and is widely applied to industries of automobile exhaust pipes, stamping products and the like. The surface corrugation is also called as concave-convex stripe, plate stripe, ridging and the like, and is a special defect of 400 series stainless steel, which mainly shows that light and dark alternate textures in the rolling direction appear on the plate surface or the corrugation formed by a client through stamping, seriously influences the use of the client, needs to increase the polishing cost of products, and influences the production efficiency and the use. The invention provides a control method for effectively controlling the surface wrinkling defect of titanium-containing ferrite stainless steel.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a method for improving the surface wrinkling defect of the titanium-containing ferritic stainless steel, so that the surface wrinkling condition of a titanium-containing stainless steel product is slight, the polishing cost of the titanium-containing ferritic stainless steel product can be effectively reduced, and the production efficiency is improved.

In order to achieve the purpose, the invention is realized by the following technical scheme:

a method for improving the surface wrinkling defects of titanium-containing ferritic stainless steel comprises the following steps:

1) annealing the black strip steel coil produced by hot rolling at the annealing temperature of 950 +/-20 ℃ for 80-160 s to ensure that core grains are completely grown and no banded structure residue exists;

pickling the annealed steel coil by sulfuric acid, and pickling by nitric acid and hydrofluoric acid to obtain a hot-rolled, annealed and pickled stainless steel plate strip;

2) carrying out cold rolling for 5-9 times by adopting a single-frame twenty-roller reversible cold rolling unit to obtain a cold-rolled stainless steel plate strip; continuously annealing the cold-rolled stainless steel plate strip at 950 +/-50 ℃ for 120 +/-30 s to obtain the cold-rolled annealed stainless steel plate strip; placing the stainless steel plate strip subjected to cold rolling annealing into a sodium sulfate neutral salt solution for electrolysis to obtain a stainless steel plate strip subjected to cold rolling annealing electrolysis, and then placing the stainless steel plate strip into a mixed solution of nitric acid and hydrofluoric acid for pickling to obtain a stainless steel plate strip subjected to cold rolling, complete annealing and pickling; and (3) carrying out tension leveling on the obtained stainless steel plate belt by using a tension leveling machine, wherein the elongation is less than or equal to 0.30%, and rolling by using a modulation rolling mill to obtain a final product.

The production method of the black strip steel coil produced by hot rolling in the step 1) comprises the following steps:

1) when molten steel is cast, strong electromagnetic stirring is applied in a secondary cooling stage, and the proportion of medium axial crystals in a casting blank is not lower than 50% at a current of 1000-2000A;

2) feeding the casting blank into a heating furnace for heating, controlling the tapping temperature at 1100-1200 ℃, and keeping the time in the furnace for 3-4 h; the hot rolling and rough rolling adopt 5-7 times of rolling to obtain a middle-thickness plate blank with the thickness of 30-40 mm; and (3) carrying out finish rolling by adopting a tandem type 7-station rolling way to obtain the black-skin steel coil with the thickness of 2.0-10.0 mm.

The tension leveling machine is used for a non-chrome-plated roller.

Compared with the prior art, the invention has the beneficial effects that:

the method can control the wrinkle defect of the surface of the titanium-containing ferrite stainless steel to a slight degree, effectively reduce the polishing cost of products and improve the production efficiency.

Drawings

FIG. 1 is a metallographic image of example 1.

FIG. 2 is a surface view of example 1.

FIG. 3 is a metallographic image of example 2.

FIG. 4 is a surface view of example 2.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings, but it should be noted that the present invention is not limited to the following embodiments.

In the following embodiments, scrap steel and alloy are adopted for steelmaking, three-step steelmaking methods of electric furnace steelmaking, AOD coarse decarburization and VOD deep decarburization are adopted for steelmaking, strong electromagnetic stirring is applied in a secondary cooling stage during molten steel casting, and the proportion of medium axial crystals in a casting blank is not lower than 50% under the current of 1000-2000A; feeding the casting blank into a heating furnace for heating, and discharging the casting blank after the casting blank is sequentially treated by a preheating section, a heating section and a soaking section; the discharging temperature is controlled to be 1100-1200 ℃, and the furnace time is 3-4 h; hot rolling and rough rolling are carried out for 5-7 times to obtain a plate blank with the thickness of 30-40 mm; and (3) carrying out finish rolling by adopting a tandem 7-station rolling way to obtain the black-skin steel coil with the thickness of 2.0-10.0 mm.

Example 1:

after steelmaking and continuous casting, the composition of 409L stainless steel is controlled as shown in Table 1:

table 1 example 1 chemical composition (balance Fe and inevitable impurities by mass)

Steel grade	C	Si	Mn	P	S	Cr	N	Ti
									409L	0.0070	0.48	0.30	0.0270	0.0005	11.30	0.0050	0.17

And (3) carrying out hot rolling, annealing and pickling on the black strip steel coil (with the thickness of 3.5mm and the width of 1250mm) after hot rolling, wherein the annealing temperature is 950 ℃, the annealing time is 120s, the obtained product crystal grains completely grow, and as shown in figure 1, no obvious stress line residue exists in the middle of the thickness of the stainless steel strip. And (3) rolling the stainless steel plate strip subjected to annealing and pickling after hot rolling for 5-9 times by adopting a single-frame twenty-roller reversible cold rolling unit to obtain the cold-rolled stainless steel plate strip. Then annealing treatment is carried out, the annealing temperature is 951 ℃, the annealing time is 115s, and electrolytic pickling and mixed acid pickling are carried out after annealing. And leveling by using a tension leveling machine, wherein the elongation of the tension leveling machine is controlled to be 0.21 percent. Finally, a final product is obtained through a modulation rolling mill, and the number of the crystal grains is 6# crystal grains, which is shown in figure 1. The final thickness of the steel strip in this example was 0.60mm, and the surface of the resulting product was wrinkled as shown in FIG. 2.

Example 2:

after steelmaking and continuous casting, the composition of 409L stainless steel is controlled as shown in Table 2:

table 2 example 2 chemical composition (balance Fe and inevitable impurities by mass)

Steel grade	C	Si	Mn	P	S	Cr	N	Ti
									409L	0.0075	0.30	0.25	0.0280	0.0011	11.41	0.0065	0.16

The hot-rolled black strip steel coil (thickness 4.0mm and width 1250mm) is subjected to hot-rolling annealing and acid pickling, wherein the annealing temperature is 943 ℃ and the annealing time is 115 s. The grains of the obtained product completely grow, and no obvious stress lines remain in the middle of the thickness of the stainless steel plate strip shown in figure 3. And (3) rolling the stainless steel plate strip subjected to annealing and pickling after hot rolling for 5-9 times by adopting a single-frame twenty-roller reversible cold rolling unit to obtain the cold-rolled stainless steel plate strip. Then continuous annealing treatment is carried out, the annealing temperature is 954 ℃, the annealing time is 110s, and electrolytic pickling and mixed acid pickling are carried out after annealing. And leveling by using a tension leveling machine, wherein the elongation of the tension leveling machine is controlled to be 0.21 percent. Finally, a final product is obtained through a modulation rolling mill, and the number of the crystal grains is 6.5# crystal grains, which is shown in figure 1. The final thickness of the steel strip in this example was 0.78mm and the surface of the resulting product was wrinkled, as shown in FIG. 4.

The invention reduces the elongation of a tension leveling machine (TLL), namely the required elongation is less than or equal to 0.30 percent, and reduces the condition that the surface of the material is wrinkled and worsened because the tension is larger and the plate shape instability along the tension direction is generated on the surface of the material; the non-chrome plating roller for the tension leveling machine has the advantages that due to the fact that the hardness of the chrome plating roller is high, concave-convex lines are easily shown on the surface of a stainless steel plate belt after the stainless steel plate belt is leveled by the material roller, wrinkling of the surface is seriously seen in appearance, and attractiveness of materials is affected. The adoption of the non-chrome-plating roller can effectively reduce the wrinkling degree of the material surface.