阅读说明：本技术 解决罐箱用ptg316冷板表面显性白斑缺陷的方法 (Method for solving surface dominant white spot defect of PTG316 cold plate for tank ) 是由 李胜雄 高建兵 孟保功 李旭初 李富 齐伟 李高峰 赵修勇 薛建军 董志刚 于 2020-05-07 设计创作，主要内容包括：本发明涉及不锈钢的冷轧,公开一种解决罐箱用PTG316冷板表面显性白斑缺陷的方法,包括：提高乳液品质,精确控制乳液各项指标；降低轧制工序中钢带表面残油量；优化冷线工序脱脂和退火工艺,清除乳液残油。本发明通过设备改进与现场管理提升,10#轧机乳液各项指标实现精确控制,浓度、温度、酸值、铁粉、皂化值各项指标完全实现工艺控制。(The invention relates to cold rolling of stainless steel, and discloses a method for solving a dominant white spot defect on the surface of a PTG316 cold plate for a tank, which comprises the following steps: the quality of the emulsion is improved, and various indexes of the emulsion are accurately controlled; the residual oil quantity on the surface of the steel strip in the rolling procedure is reduced; and the degreasing and annealing processes of the cold wire process are optimized, and the residual oil of the emulsion is removed. According to the invention, through equipment improvement and field management promotion, various indexes of 10# rolling mill emulsion are accurately controlled, and various indexes of concentration, temperature, acid value, iron powder and saponification value are completely controlled.)

1. A method for solving the dominant white spot defect on the surface of a PTG316 cold plate for a tank is characterized by comprising the following steps:

the quality of the emulsion is improved, and various indexes of the emulsion are accurately controlled;

the residual oil quantity on the surface of the steel strip in the rolling procedure is reduced;

and the degreasing and annealing processes of the cold wire process are optimized, and the residual oil of the emulsion is removed.

2. The method for solving the dominant white spot defect on the surface of the PTG316 cold plate for the tank and the tank as claimed in claim 1, wherein the improving the quality of the emulsion comprises the following steps: the concentration of the emulsion was set to 1.5% or more.

3. The method for solving the dominant white spot defect on the surface of the PTG316 cold plate for the tank and the tank as claimed in claim 1, wherein the improving the quality of the emulsion comprises the following steps: the heating mode of the 10# rolling mill is set as steam indirect heating.

4. The method for solving the dominant white spot defect on the surface of the PTG316 cold plate for the tank and the tank as claimed in claim 1, wherein the improving the quality of the emulsion comprises the following steps: the emulsion crude oil is stored in a crude oil storage tank.

5. The method for solving the dominant white spot defect on the surface of the PTG316 cold plate for the tank and the tank as claimed in claim 1, wherein the improving the quality of the emulsion comprises the following steps: 2 sets of magnetic filtration systems were configured in a 10# rolling mill.

6. The method for solving the dominant white spot defect on the surface of the PTG316 cold plate for the tank and the tank as claimed in claim 1, wherein the reducing of the surface residual oil amount of the steel strip in the rolling process comprises the following steps: the oil scraping roller on the outlet side of the 10# rolling mill is set as a felt roller.

7. The method for solving the dominant white spot defect on the surface of the PTG316 cold plate for the tank and the tank as claimed in claim 1, wherein the reducing of the surface residual oil amount of the steel strip in the rolling process comprises the following steps: 1 group of air knife devices are arranged at the outlet side of the 10# rolling mill.

8. The method for solving the dominant white spot defect on the surface of the PTG316 cold plate for the tank and the container as claimed in claim 1, wherein the optimized cold line process degreasing and annealing process comprises the following steps: the conductivity of the cold line degreasing section is controlled to be more than 7.5 mu S/cm.

9. The method for solving the dominant white spot defect on the surface of the PTG316 cold plate for the tank and the container as claimed in claim 1, wherein the optimized cold line process degreasing and annealing process comprises the following steps: the sleeve punching speed of the cold wire is controlled to be less than or equal to 50 m/min.

10. The method for solving the dominant white spot defect on the surface of the PTG316 cold plate for the tank and the container as claimed in claim 1, wherein the optimized cold line process degreasing and annealing process comprises the following steps: controlling the furnace temperature of a 9-12 area in the furnace area process to be 1000-1050 ℃.

Technical Field

The invention relates to cold rolling of stainless steel, in particular to rolling of a PTG316 cold plate for a tank, and particularly relates to a method for solving the apparent white spot defect on the surface of the PTG316 cold plate for the tank.

Background

The PTG316 for the tank industry is developed by the cooperation of Tai-Gai stainless steel Limited company and Nantong centralized company in 2006, and has special specifications of thickness and width of products, excellent pitting corrosion resistance, intercrystalline corrosion resistance and excellent mechanical properties. It is used for manufacturing tank containers, can be used for transporting various goods including gas, powder, liquid and other dangerous goods and non-dangerous goods, and can also be used for transporting various perishable and non-perishable foods, such as: orange juice, wine, even liquid chocolate, and other food grade products. The annual output of the PTG316 cold plate for the Tai steel in the tank industry is about 4 ten thousand tons, the profit reaches 1.2 million yuan, the profit of each ton of steel is high, the market added value is large, and the PTG316 cold plate for the tank industry is a star-shaped product of the Tai steel in the stainless steel industry.

The PTG316 cold plate for the tank industry is produced in a wide area of a Tai steel cold rolling plant, a large number of 'white spot' defects appear after degreasing and annealing of a cold line (see figure 1), the surface quality level of a product is seriously influenced, and a large number of complaints and dissatisfaction are proposed by customers, so that the production cost is greatly increased. Therefore, a solution to the "white spot" defect is urgently needed.

Disclosure of Invention

The invention aims to reduce the white spot defect reject ratio of the PTG316 cold plate used in the tank industry to be less than 1%, improve the quality level of the PTG316 cold plate material object and meet the customer requirements with high standard. To achieve the above object, the present invention provides a method for solving the dominant white spot defect on the surface of the PTG316 cold plate for a tank.

Specifically, the method for solving the dominant white spot defect on the surface of the PTG316 cold plate for the tank comprises the following steps:

the quality of the emulsion is improved, and various indexes of the emulsion are accurately controlled;

the residual oil quantity on the surface of the steel strip in the rolling procedure is reduced;

and the degreasing and annealing processes of the cold wire process are optimized, and the residual oil of the emulsion is removed.

The method for solving the dominant white spot defect on the surface of the PTG316 cold plate for the tank comprises the following steps: the concentration of the emulsion was set to 1.5% or more.

The method for solving the dominant white spot defect on the surface of the PTG316 cold plate for the tank comprises the following steps: the heating mode of the 10# rolling mill is set as steam indirect heating.

The method for solving the dominant white spot defect on the surface of the PTG316 cold plate for the tank comprises the following steps: the emulsion crude oil is stored in a crude oil storage tank.

The method for solving the dominant white spot defect on the surface of the PTG316 cold plate for the tank comprises the following steps: 2 sets of magnetic filtration systems were configured in a 10# rolling mill.

The method for solving the apparent white spot defect on the surface of the PTG316 cold plate for the tank comprises the following steps of: the oil scraping roller on the outlet side of the 10# rolling mill is set as a felt roller.

The method for solving the apparent white spot defect on the surface of the PTG316 cold plate for the tank comprises the following steps of: 1 group of air knife devices are arranged at the outlet side of the 10# rolling mill.

The method for solving the dominant white spot defect on the surface of the PTG316 cold plate for the tank comprises the following steps of: the conductivity of the cold line degreasing section is controlled to be more than 7.5 mu S/cm.

The method for solving the dominant white spot defect on the surface of the PTG316 cold plate for the tank comprises the following steps of: the sleeve punching speed of the cold wire is controlled to be less than or equal to 50 m/min.

The method for solving the dominant white spot defect on the surface of the PTG316 cold plate for the tank comprises the following steps of: controlling the furnace temperature of a 9-12 area in the furnace area process to be 1000-1050 ℃.

The technical scheme of the invention has the following beneficial effects:

(1) according to the invention, through equipment improvement and field management promotion, various indexes of 10# rolling mill emulsion are accurately controlled, and various indexes of concentration, temperature, acid value, iron powder and saponification value are completely controlled;

(2) the user evaluates the height of the PTG316 cold plate produced by the invention, the satisfaction degree of the user is greatly improved, and by comparison, the quality of the PTG316 cold plate is superior to that of an imported product;

(3) the white spot defect fraction defective of the PTG316 cold plate for the tank industry produced by the method is reduced to 0 percent from the previous 10 percent;

(4) the invention fundamentally solves the problem of white spot defect of the PTG316 cold plate for the tank and box industry of the company in recent years, the surface quality of the product is greatly improved (figure 2), the market share reaches more than 85 percent, and the profit is increased by 600 ten thousand yuan through accumulation in one year.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention.

FIG. 1 is a white spot defect of a PTG316 cold plate for the tank and container industry;

fig. 2 is a PTG316 cold plate produced by the method of the invention for solving the dominant white spot defect on the surface of the PTG316 cold plate for a tank.

Detailed Description

The present invention will be described in detail with reference to the following embodiments in order to fully understand the objects, features and effects of the invention. The process of the present invention employs conventional methods or apparatus in the art, except as described below. The following noun terms have meanings commonly understood by those skilled in the art unless otherwise specified.

Specifically, the method for solving the dominant white spot defect on the surface of the PTG316 cold plate for the tank comprises the following steps:

(1) the quality of the emulsion is improved, and various indexes of the emulsion are accurately controlled;

(2) the residual oil quantity on the surface of the steel strip in the rolling procedure is reduced;

(3) and the degreasing and annealing processes of the cold wire process are optimized, and the residual oil of the emulsion is removed.

Through comparison, analysis and field tracking, the inventor finds that the apparent white spot defect on the surface of the PTG316 cold plate for the tank is mainly caused by four aspects of large emulsion quality fluctuation, more surface emulsion residues, insufficient degreasing effect and low-temperature annealing. In order to solve the white spot defect, the inventor improves the emulsion quality, reduces the surface residual oil quantity of the steel strip in the rolling process and optimizes the degreasing and annealing process of the cold wire process by improving equipment and promoting field management, so that the white spot defect fraction defective of the PTG316 cold plate for the tank industry is reduced to 0 percent from the previous 10 percent, and the user satisfaction is greatly improved.

In some preferred embodiments, the invention provides a method for solving the dominant white spot defect on the surface of a PTG316 cold plate for a tank, which comprises the following steps:

(1) improve the quality of the emulsion and accurately control various indexes of the emulsion.

The emulsion, also called "emulsion", is used for lubricating cooling of the PTG316 cold plate for rolling tank containers.

The PTG316 cold plate for the tank box is produced by adopting a 10# rolling mill, wherein the 10# rolling mill is a 2100mm wide S6-HighSUDWING eighteen-roller rolling mill.

The traditional heating mode of the 10# rolling mill is electric heating, and the electric heating has the defects of low heating efficiency and unstable temperature control. The heating mode is changed into steam indirect heating, and particularly, the indirect heating of the steam and the emulsion is realized through a U-shaped tubular heat exchange device. The invention can improve the heating efficiency and stably control the temperature at 45-65 ℃ by steam indirect heating.

In the prior art, the mode of storing the crude oil of the emulsion in the 10# rolling mill is an oil drum mode, and the oil filling amount is not accurate and the labor intensity of personnel is high easily caused by the oil drum mode. According to the invention, the emulsion crude oil is stored in the crude oil storage tank, so that the accurate control of the oil adding amount, the accurate control of the concentration and the great reduction of the labor intensity of personnel can be realized.

According to the invention, two sets of magnetic filtration systems are prepared in the 10# rolling mill, so that the content of ferromagnetic impurities in the emulsion can be reduced to below 150ppm, and the white spot defect of a PTG316 cold plate is further reduced.

The invention also increases the concentration of the emulsion from the previous 1% to more than 1.5% (preferably 1.5% -4.0%), and is beneficial to improving the lubricity and reducing the generation of iron powder by increasing the concentration of the emulsion.

(2) The residual oil quantity on the surface of the steel strip in the rolling procedure is reduced.

Emulsion oil is remained on the surface of the steel strip after oil scraping in the rolling process, and when the residual oil on the surface of the steel strip is high, the degreasing load of the cold line process is increased, so that the surface of the steel strip is difficult to clean, and the white spot defect is increased. According to the invention, the oil scraping roller on the outlet side of the 10# rolling mill is replaced by the felt roller from the copper roller, so that the surface residual oil quantity of the steel strip in the rolling process can be effectively reduced.

The invention is provided with 1 group of air knife devices at the outlet side of a 10# rolling mill and used for blowing residual oil and other impurities on the surface of a steel strip. Therefore, the defect of white spots of the PTG316 cold plate caused by too high residual oil on the surface of the steel strip can be effectively reduced.

(3) And the degreasing and annealing processes of the cold wire process are optimized, and the residual oil of the emulsion is removed.

The conductivity of the cold line degreasing section is used for measuring the content index of the degreasing agent. When the conductivity of the cold line degreasing section is low, the content of the degreasing agent is low, and the degreasing effect is poor. According to the invention, the conductivity of the cold line degreasing section is controlled to be more than 7.5 muS/cm, so that the degreasing effect can be improved, and the emulsion residual oil on the surface of the steel strip can be reduced.

The cold line sleeve punching speed refers to the quality inspection loop of the degreasing section and the furnace area, so that the two process sections can normally run, the sleeve punching speed is the speed of the strip steel entering the loop area, and the faster the speed is, the shorter the retention time of the strip steel in the degreasing section area is. According to the invention, the sleeve punching speed of the cold line is controlled to be less than or equal to 50m/min, so that the degreasing time of the rolled steel strip in a degreasing section can be prolonged, and the degreasing effect is improved.

Preferably, the furnace temperature of a 9-12 area in the furnace area process is controlled to be 1000-1050 ℃. In the prior art, the furnace temperature of a 9-12 area in the furnace area process is 930 ℃, and the invention can increase the surface oxide scale after annealing by one time compared with the prior art on the premise of not influencing the mechanical property of the final steel strip by increasing the furnace temperature of the 9-12 area in the furnace area process to 1000-1050 ℃, thereby effectively removing the oxide scale at the emulsion residue during acid cleaning.

The invention can accurately control various indexes of the emulsion by optimizing the prior art. Specifically, the indexes of the emulsion are as follows: the concentration is 1.5-4.0%, the temperature is 45-65 ℃, and the acid value is 15-50mgKOH g^-150-150ppm of iron powder, and a saponification value of 155-^-1。

Through the effective implementation of the invention, the problem of white spot defect of the PTG316 cold plate for the tank and container industry of the company which is puzzled all the time in recent years is fundamentally solved, the surface quality of the product is greatly improved (figure 2), the market share reaches more than 85 percent, the annual cumulative increase of the profit is 600 ten thousand yuan, and the quality objection rate of white spot reasons is reduced to 0 percent.