阅读说明：本技术 一种消除镀锌家电板白痕的方法 (Method for eliminating white marks of galvanized household electrical appliance board ) 是由 赵刚 曹垒 张婷 马燕 于 2020-07-17 设计创作，主要内容包括：本发明公开了一种消除镀锌家电板白痕的方法,在经过铁水、板坯、热轧卷、轧硬卷后形成镀锌家电板；其中,热轧卷具体是：利用热轧机,通过加热炉对板坯进行加热,再经粗轧、精轧、层流冷却,最后卷取成热轧卷,其中热轧的工艺参数为：终轧温度880±20℃,卷取温度650±20℃,进入下道酸轧工序,产出轧硬卷。通过本发明镀锌家电板白痕判次量从248吨下降到0吨,按照镀锌次品500元/吨测算,每月可挽回损失12.4万元；其次是间接效益也较高,主要是镀锌家电板白痕问题解决后,进一步提升镀锌家电板产品质量和市场竞争力。(The invention discloses a method for eliminating white marks of galvanized household electrical plates, which is characterized in that the galvanized household electrical plates are formed after molten iron, plate blanks, hot-rolled coils and hard-rolled coils are processed; wherein, the hot-rolled coil is specifically: utilizing a hot rolling mill, heating a plate blank by a heating furnace, then carrying out rough rolling, finish rolling and laminar cooling, and finally coiling into a hot rolled coil, wherein the hot rolling process parameters are as follows: and the final rolling temperature is 880 +/-20 ℃, the coiling temperature is 650 +/-20 ℃, the next acid rolling process is carried out, and the rolled hard coil is produced. The number of times of judging the white marks of the galvanized household electrical panel is reduced from 248 tons to 0 ton, and the loss of 12.4 ten thousand yuan can be saved every month according to the measurement of 500 yuan/ton of galvanized inferior-quality products; and the indirect benefit is higher, and the quality and market competitiveness of the galvanized household appliance plate product are further improved after the problem of white marks of the galvanized household appliance plate is mainly solved.)

1. A method for eliminating white marks on galvanized household electrical boards is characterized by comprising the following steps:

step 1, molten iron: processing the raw materials of the sintered ore and the coke by using blast furnace equipment to produce molten iron, and carrying out the next steelmaking process to produce molten steel and plate blanks;

step 2, slab: molten steel is produced by converter equipment by using the molten iron of the previous procedure as a raw material, and the molten steel is used for producing a slab by a slab caster, wherein the component requirements of the household electrical appliance board are as follows: c is less than or equal to 0.1 percent, Si is less than or equal to 0.04 percent, Mn is more than or equal to 0.1 percent and less than or equal to 0.4 percent, P is less than or equal to 0.02 percent, S is less than or equal to 0.008 percent, Cu is less than or equal to 0.02 percent, Ni is less than or equal to 0.02 percent, and the steel is subjected to hot rolling in the next procedure to produce;

step 3, hot rolling the coil: the method comprises the following steps of heating a plate blank in the previous procedure by a hot rolling mill through a heating furnace, carrying out rough rolling, finish rolling and laminar cooling, and finally coiling into a hot rolled coil, wherein the hot rolling process parameters are as follows: the final rolling temperature is 880 +/-20 ℃, the coiling temperature is 650 +/-20 ℃, the next acid rolling procedure is carried out, and the rolled hard coil is produced;

Step 4, rolling hard rolls: the hot-rolled coil of the previous procedure is processed and rolled by acid continuous rolling equipment, the surface of the hot-rolled coil is firstly pickled, then the hot-rolled coil is rolled by a six-roller five-continuous rolling cold rolling mill, and a hard-rolled coil is produced, wherein the specific technological parameters are as follows: 1) the process stage comprises the following steps: the pickling speed is less than or equal to 200mpm, the acid liquor concentration is more than or equal to 30g/L in the No. 1 tank, more than or equal to 80g/L in the No. 2 tank, more than or equal to 140g/L in the No. 3 tank, and Fe²⁺Concentration: the number 1 tank is not more than 130g/L, the number 2 tank is not more than 100g/L, and the number 3 tank is not more than 50 g/L; 2) A rolling mill section: the concentration of the emulsion is more than or equal to 1 percent and less than or equal to 3 percent of the No. 1-4 stand and more than or equal to 3 percent of the No. 5 stand which is more than or equal to 0.3 percent; the next procedure is hot galvanizing, and finally a finished product of the galvanized household appliance plate is produced;

step 5, galvanizing the household electrical board: the hard rolled coil of the previous procedure is cleaned, annealed, hot galvanized, leveled, passivated and oiled by the hot galvanizing procedure, and the key control point of a hot galvanizing zinc pot is the aluminum content of the zinc pot, and the requirements are as follows: the aluminum content of the zinc pot is more than or equal to 0.18 percent and less than or equal to 0.22 percent, and the finished galvanized household electric board is finally produced after offline judgment, bundling, weighing, packaging and warehousing.

2. The method for eliminating the white mark of the galvanized household appliance board according to the claim 1, wherein the sintering ore in the step 1 is formed by burning the blending ore, the auxiliary material and the fuel.

3. The method for eliminating the white mark of the galvanized household appliance according to the claim 1, wherein the coke in the step 1 is formed by burning mixed coal and coal gas into metallurgical coke.

4. The method for eliminating the white mark of the galvanized household appliance as claimed in claim 1, wherein the aluminum content of the zinc pot in the step 5 is 0.2 percent.

Technical Field

The invention relates to the technical field of galvanized household electrical appliance boards, in particular to a method for eliminating white marks of a galvanized household electrical appliance board.

Background

The sand steel cold rolling has two acid continuous rolling units with annual output of 200 ten thousand 1420mm and one hot galvanizing unit with annual output of 40 ten thousand tons, the hot galvanizing unit is designed and generally responsible for the process by German Simmark company, and core equipment is imported abroad. The production line has advanced technology, can provide high-precision and high-quality hot galvanized plates for the subsequent processes, and mainly positions high-end household appliance plates, automobile plates and high-grade building color-coated plates. The sand steel hot galvanizing line 2015 reaches the production standard, the production of the building boards is mainly used in the initial production period, the production of the household electric boards is gradually debugged from 2017, and the household electric boards are produced in batches in the next half year. However, with the intensified homogeneity competition of galvanized products, the requirements of customers on the product quality are higher and higher, from 8 months in 2017, the white mark defect problem of galvanized household electrical appliance boards is prominent, the monthly judgment number is large, the product quality and the market development are affected, and the market of the galvanized household electrical appliance boards is ensured to occupy a place for improving the product quality.

The appearance of the white mark defect of the galvanized household electrical appliance board is as follows:

(1) morphology and distribution: the galvanized household electrical appliance board white mark defects are irregularly distributed, the upper surface and the lower surface can be generated, the positions of the transverse surface and the longitudinal surface of the strip steel are not fixed, and once the white mark appears, the white mark is continuous, such as the whole half coil or the through coil.

(2) The corresponding relation between the galvanized white mark defect and the hard rolled coil is as follows: the galvanized unit produces the household electrical panel, find the white mark defect, the half coil of the galvanized entrance backs off, through sampling the galvanized entrance and sampling after galvanizing, there is slight white mark defect on the roll hard coil, the white mark defect after galvanizing is continuous before galvanizing, confirm that the white mark defect is that the process produces before galvanizing basically, exclude the possibility that the galvanized unit produces.

(3) Surface roughness of galvanized white marks: the household appliance board white mark defect is sampled and tracked, the roughness is different from the white mark defect and the normal position through low-power and roughness measurement, and the local roughness change forms regular light reflection as seen from the sample wafer inspection condition, so that the reason for causing the hot galvanizing visual white mark defect is shown. The roughness of the galvanized temper mill working roll is measured to be 2.5-3.0 mu m, actually about 2.8 mu m, the white mark area is tiny in crystal grains after being galvanized, the average roughness of the white mark area is 0.701 mu m, the normal area is 0.801 mu m and is slightly lower than the normal area through the measurement of a roughness meter.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a method for eliminating white marks of galvanized household electrical appliances.

The invention adopts the following technical scheme for solving the technical problems:

the method for eliminating the white mark of the galvanized household electrical appliance comprises the following steps:

step 1, molten iron: processing the raw materials of the sintered ore and the coke by using blast furnace equipment to produce molten iron, and carrying out the next steelmaking process to produce molten steel and plate blanks;

step 2, slab: molten steel is produced by converter equipment by using the molten iron of the previous procedure as a raw material, and the molten steel is used for producing a slab by a slab caster, wherein the component requirements of the household electrical appliance board are as follows: c is less than or equal to 0.1 percent, Si is less than or equal to 0.04 percent, Mn is more than or equal to 0.1 percent and less than or equal to 0.4 percent, P is less than or equal to 0.02 percent, S is less than or equal to 0.008 percent, Cu is less than or equal to 0.02 percent, Ni is less than or equal to 0.02 percent, and the steel is subjected to hot rolling in the next procedure to produce;

step 3, hot rolling the coil: the method comprises the following steps of heating a plate blank in the previous procedure by a hot rolling mill through a heating furnace, carrying out rough rolling, finish rolling and laminar cooling, and finally coiling into a hot rolled coil, wherein the hot rolling process parameters are as follows: the final rolling temperature is 880 +/-20 ℃, the coiling temperature is 650 +/-20 ℃, the next acid rolling procedure is carried out, and the rolled hard coil is produced;

Step 4, rolling hard rolls: the hot-rolled coil of the previous procedure is processed and rolled by acid continuous rolling equipment, the surface of the hot-rolled coil is firstly pickled, then the hot-rolled coil is rolled by a six-roller five-continuous rolling cold rolling mill, and a hard-rolled coil is produced, wherein the specific technological parameters are as follows: 1) the process stage comprises the following steps: the pickling speed is less than or equal to 200mpm, the acid liquor concentration is more than or equal to 30g/L in the No. 1 tank, more than or equal to 80g/L in the No. 2 tank, more than or equal to 140g/L in the No. 3 tank, and Fe²⁺Concentration: the number 1 tank is not more than 130g/L, the number 2 tank is not more than 100g/L, and the number 3 tank is not more than 50 g/L; 2) A rolling mill section: the concentration of the emulsion is more than or equal to 1 percent and less than or equal to 3 percent of the No. 1-4 stand and more than or equal to 3 percent of the No. 5 stand which is more than or equal to 0.3 percent; the next procedure is hot galvanizing, and finally a finished product of the galvanized household appliance plate is produced;

step 5, galvanizing the household electrical board: the hard rolled coil of the previous procedure is cleaned, annealed, hot galvanized, leveled, passivated and oiled by the hot galvanizing procedure, and the key control point of a hot galvanizing zinc pot is the aluminum content of the zinc pot, and the requirements are as follows: the aluminum content of the zinc pot is more than or equal to 0.18 percent and less than or equal to 0.22 percent, and the finished galvanized household electric board is finally produced after offline judgment, bundling, weighing, packaging and warehousing.

As a further optimization scheme of the method for eliminating the white marks of the galvanized household electrical appliance board, in the step 1, the sinter is formed by burning uniformly mixed ore, auxiliary materials and fuel.

As a further optimization scheme of the method for eliminating the white marks of the galvanized household electrical appliance board, in the step 1, the coke is formed by burning mixed coal and coal gas into metallurgical coke.

As a further optimization scheme of the method for eliminating the white mark of the galvanized household electrical appliance, the aluminum content of the zinc pot in the step 5 is 0.2 percent.

Compared with the prior art, the invention adopting the technical scheme has the following technical effects:

by adopting the method, the white mark judgment quantity of the galvanized household electrical panel is reduced from 248 tons to 0 ton, and the loss of 12.4 ten thousand yuan can be recovered every month according to the measurement of 500 yuan/ton galvanized defective products; and the indirect benefit is higher, and the quality and market competitiveness of the galvanized household appliance plate product are further improved after the problem of white marks of the galvanized household appliance plate is mainly solved.

Drawings

FIG. 1 is a macroscopic and magnified topographical comparison of white mark areas and normal areas of a galvanized household electrical panel; wherein, (a) is the macroscopic morphology of the white mark area and the normal area of the galvanized household electrical appliance plate; (b) the method comprises the following steps of (1) preparing a galvanized household electrical board sample plate, wherein an area A and an area C are normal board surfaces (without white mark defects), an area B is a white mark area, pictures are magnified by 50 times and form and roughness detection positions at different positions, (C) preparing the form and roughness detection positions of the normal area of the galvanized household electrical board A, (d) preparing the form and roughness detection positions of the white mark area of the galvanized household electrical board B, and (e) preparing the form and roughness detection positions of the normal area of the galvanized household electrical board C.

Fig. 2 is a flow chart of the present invention.

Detailed Description

The technical scheme of the invention is further explained in detail by combining the attached drawings:

FIG. 1 is a macroscopic and magnified topographical comparison of white mark areas and normal areas of a galvanized household electrical panel; wherein, in FIG. 1, (a) is the macroscopic morphology of the white mark area and the normal area of the galvanized household electrical appliance board; fig. 1 (B) shows a galvanized home electric board sample, areas a and C are normal board surfaces (without white mark defects), area B is a white mark area, and the picture is a 50-fold magnification detection position of morphology and roughness at different positions, fig. 1 (C) shows a normal area morphology and a detection roughness position of a galvanized home electric board a, fig. 1 (d) shows a white mark area morphology and a detection roughness position of a galvanized home electric board B, and fig. 1 (e) shows a normal area morphology and a detection roughness position of a galvanized home electric board C.

Firstly, checking the position, rule, distribution and main appearance specification of the white mark defect of the galvanized household electrical appliance plate; secondly, comparing the difference between the roughness of the white mark defect and the normal position, and checking out possible reasons due to the main process changes of the coil with the white mark defect and the normal coil in the processes of steel making, hot rolling, acid rolling and galvanizing; the surface condition is tracked again by properly adjusting the processes of the four procedures; and finally, tracking a comparison result through a comparison and adjustment process, determining the optimized process solidification, forming a standard file, and implementing and executing to thoroughly solve the white mark defect.

The invention relates to a method for formulating white mark defects, which is mainly characterized in that the method is used for optimally controlling the process parameters of controlling the aluminum content in galvanization, managing a zinc pot, managing acid rolling emulsion, controlling the acid rolling period, reducing the speed of a rolling mill, heating and coiling temperature, steelmaking components and the like, and the best method for improving the white mark defects is determined through continuous debugging production.

Table 1 shows roughness test comparison between white mark area and normal area of galvanized household electrical appliance board.

TABLE 1

Roughness/mum	1	2	3	4	Mean value of
						White mark area (B zone)	0.705	0.680	0.718	0.702	0.701
Normal zone (A \ C zone)	0.810	0.796	0.801	0.798	0.801

The galvanized household electrical panel white mark judging rate is 4% in 8 months in 2017, reaches 8.7% in 12 months in 2017, then falls back to some extent, is greatly improved from a small-batch optimized hot rolling process in 3 months in 2018 to 5 months, reaches the lowest 1.6%, and in addition, the mechanical properties such as galvanized yield, tensile strength and the like are all within the judging standard range, so that the coiling temperature of the household electrical panel hot coils in the last ten months of 5 months is all reduced, the household electrical panel white mark judging rate in 6 months is controlled below 1%, reaches 0.3%, and no white mark is judged again from 7 months in 18 years.

1. A galvanizing procedure: aiming at the white mark defect of the galvanized household electrical appliance plate, although the white mark defect is not generated in the galvanizing process, the literature describes that the fluidity of zinc liquid can be improved by reducing the aluminum content of a galvanizing zinc pot, which is beneficial to improving the surface quality, but the secondary defects such as zinc slag and the like can be caused by increasing the zinc slag in the galvanizing zinc pot due to too low aluminum content. By field practice, the aluminum content is reduced from 0.18-0.22% (target 0.2%) to the range of 0.15-0.18% (target 0.165%), and the white mark defect is improved to a certain extent. However, after the aluminum content is reduced, the slag amount in the zinc pot is obviously increased, the occurrence risk of the strip steel zinc slag is increased, the working strength and the working capacity can be greatly increased only by increasing the slag fishing amount and the slag fishing frequency, and then the aluminum content in the zinc pot is increased to 0.17% -0.19% (target 0.18%), the white mark judgment amount is slightly reduced, but the problem is not completely solved.

2. Acid rolling process: the method has the advantages that the white mark defect and the surface cleanliness of a hard rolled coil are in a certain relation, the problem of the hard rolled coil cleanliness is the key work of acid rolling, and aiming at improving the cleanliness of rolled hard strip steel, measures are taken in an acid rolling workshop, namely, the concentration of emulsion is reduced, the concentration of 1# -4# frame emulsion is reduced from 2.0% to 1.0% -1.5%, and the concentration of 5# frame emulsion is reduced from more than 1.0% to less than 0.5%; and secondly, when the household electrical board is rolled, the acid rolling saponification value is ensured to be more than 150mgKOH/g, the magnetic filter is normally opened, and the iron powder and the ash content in the emulsion are specified in detail. Through the measures, the surface cleanliness of the rolled hard strip steel of the household appliance plate is greatly improved, but the number of the white marks is reduced to some extent, but the complete prevention is not completely avoided.

3. A hot rolling procedure:

(1) DX52D + Z of SPHD (1) with the same composition as galvanized household electrical appliance board totally 4 rolls, and all defects are judged by white marks. According to the examination that the average value of the coiling temperature is more than 680 ℃, if the average value of the coiling temperature of D808165801 exceeds 710 ℃, further, the direct relation between the white mark defect of the galvanized household electrical appliance plate and the hot rolling coiling temperature is further explained under the composition;

(2) adjusting the hot rolling coiling temperature of the galvanized household electrical appliance board DX51D + Z-E for debugging, as shown in Table 2;

TABLE 2

Hot rolling coiling temperature	White mark	Total amount of examination	White mark ratio	Remarks for note
					650 plus or minus 20 ℃ (after adjustment)	37	2597	1.42%
680 +/-20 ℃ (before adjustment)	144	1901	7.57%
					Total of	181	4498	4.02%

From the appearance of white mark defects of galvanized household electrical boards in batches to the two aspects of galvanizing and acid rolling, a great deal of improvement work is done after half a year, but the white mark defects are not obviously improved. And then, the hot rolling process is optimized through debugging, the improvement condition of the white mark defect is tracked mainly by reducing the hot rolling coiling temperature, the coiling temperature coil is reduced through small batch debugging, the temperature is regulated to 650 +/-20 ℃ from 680 +/-20 ℃, the surface quality of the galvanized household appliance plate is greatly improved, and the effect is good. Preliminarily determining that the white mark defect of the galvanized household appliance plate has a great relationship with the surface state of the high-temperature coil, and from the subsequent white mark judgment ratio of the high-temperature coil to the low-temperature coil, judging that the low-temperature coil basically has no white mark, and indicating the direction for subsequent attack and customs.

4. A steel making process: DX52D + Z is for guaranteeing the performance, and coiling temperature can not descend, can only change from SPHD (1) to SPHE from the inside steel grade through modifying steelmaking composition, is close to IF (6) composition, and DX52D + Z hot coil coiling temperature still is according to 680 ℃ control, and the galvanizing production does not have white marks.

To sum up:

(1) the galvanized household electrical appliance plate white mark defect is actually a galvanized original plate rolled hard coil with inconsistent roughness, and the roughness of the white mark defect position is higher than that of a normal position by about 0.1 mu m for macroscopic expression of roughness difference after galvanization is leveled;

(2) aiming at the white mark defect of the galvanized household electrical appliance plate, the aluminum content of a zinc pot is reduced in the galvanization; the acid rolling ensures the cleanness of the emulsion by reducing the concentration of the emulsion and controlling iron powder, ash content and the like of the emulsion, and after the measures, the cleanness of the surface of the strip steel is greatly improved, the cold rolling quality management level is also improved, but the problem of the white mark defect is not thoroughly solved;

(3) in the household appliance plate with the SPHD (1) component, the white mark defect is obviously improved by reducing the coiling temperature, the number of times of judgment is reduced from 248 tons to 0 ton per month originally, the coiling temperature of the hot rolling process of the household appliance plate is adjusted from 680 +/-20 ℃ to 650 +/-20 ℃, and a process file is formed and issued; DX52D + Z is changed into SPHE (approximate IF (6)) after avoiding SPHD (1) component, the coiling temperature is 680 ℃, the galvanized household electrical board has no white mark defect, but the final mechanical property does not meet the requirement, and the production cost is greatly increased;

(4) Through the analysis, the galvanized household appliance plate white mark defect is not caused by a single factor, is caused by mismatching of steel-making components and hot rolling coiling temperature, belongs to the result of combined action of double factors, and is more suitable for reducing the coiling temperature through balancing quality and cost for common household appliance plates; for large household appliances with higher requirements on galvanization performance, the white mark defect of a galvanized household appliance plate is solved only by adjusting steel-making components.

The method for eliminating the white mark of the galvanized household electrical appliance board disclosed by the invention comprises the following steps of:

step 1, molten iron: processing raw materials of sinter (uniformly mixed ore, auxiliary materials and fuel are combusted into sinter) and coke (mixed coal and coal gas are combusted into metallurgical coke) by using blast furnace equipment to produce molten iron, and entering a next steelmaking process to produce molten steel and plate blanks;

step 2, slab: molten steel is produced by converter equipment by using the molten iron of the previous procedure as a raw material, and the molten steel is used for producing a slab by a slab caster, wherein the component requirements of the household electrical appliance board are as follows: c is less than or equal to 0.1 percent, Si is less than or equal to 0.04 percent, Mn is more than or equal to 0.1 percent and less than or equal to 0.4 percent, P is less than or equal to 0.02 percent, S is less than or equal to 0.008 percent, Cu is less than or equal to 0.02 percent, Ni is less than or equal to 0.02 percent, and the steel is subjected to hot rolling in the next procedure to produce;

Step 3, hot rolling the coil: the plate blank in the previous process is heated by a heating furnace by using a hot rolling mill, and then is subjected to rough rolling, finish rolling and laminar cooling, and finally is coiled into a hot rolled coil, wherein the main process parameters of hot rolling are that the final rolling temperature is 880 +/-20 ℃, the coiling temperature is 650 +/-20 ℃, the next acid rolling process is carried out, and the hard rolled coil is produced. The process is a key process for solving the white mark defect of the galvanized household electrical plate, wherein the coiling temperature set by a pyrometer before coiling plays a decisive factor for solving the white mark defect, and the formation condition of iron oxide on the surface of a hot-rolled coil is changed by reducing the coiling temperature set value, the structure, compactness and the like of the iron oxide are optimized, so that the iron oxide on the surface can be removed more easily in a process acid washing section of a subsequent acid rolling process, and the white mark defect is favorably solved. The hot rolling coiling temperature is high, the occurrence rate and the judgment rate of white marks are high, the coiling temperature is mainly high, the thickness of iron scales on the surface of a hot rolled coil is large and compact, the iron scales are not easy to remove after acid cleaning, similar white mark defects appear after rolling, the white mark judgment rate of the galvanized household electrical plate is more than 4 percent after galvanizing. The hot rolling coiling temperature is reduced through small batch debugging, the coiling temperature process is reduced from 680 +/-20 ℃ to 650 +/-20 ℃, the occurrence rate and the frequency judging rate of white marks are greatly reduced, but the white mark defects are sporadically found, the white mark defects are found to be the upper limit of the target value of the hot rolling coiling temperature, after the hot rolling coiling temperature is continuously adjusted and set to be 650 +/-20 ℃ in batches through multiple debugging and verification, the actual coiling temperature is also in the range, the galvanized household electrical plate has no cause white mark judgment, and the effect is obvious;

Step 4, rolling hard rolls: the hot-rolled coil of the previous procedure is processed and rolled by acid continuous rolling equipment, the surface of the hot-rolled coil is firstly pickled, then the hot-rolled coil is rolled by a six-roller five-continuous rolling cold mill, and a hard-rolled coil is produced, wherein the specific main technological parameters are as follows: 1) the process stage comprises the following steps:the pickling speed is less than or equal to 200mpm, the acid liquor concentration is more than or equal to 30g/L in the No. 1 tank, more than or equal to 80g/L in the No. 2 tank, more than or equal to 140g/L in the No. 3 tank, and Fe²⁺Concentration: the number 1 can is not more than 130g/L, the number 2 can is not more than 100g/L, the number 3 can is not more than 50g/L, and the optimized pickling speed is favorable for defect improvement; 2) a rolling mill section: the concentration of the emulsion is more than or equal to 1 percent and less than or equal to 3 percent of the No. 1-4 stand and more than or equal to 3 percent of the No. 5 stand, and the concentration optimizing effect is limited. The next procedure is hot galvanizing, and finally, a finished product of the galvanized household appliance plate is produced. The acid washing section of the process is also a key process for solving the white mark defect of the galvanized household electrical board, the coiled household electrical board is reduced mainly by the previous hot rolling, and the acid washing speed is properly reduced by the acid washing section of the process, so that the surface of a hot-rolled coil is ensured to be washed clean by oxidized ferrite, and the white mark defect is favorably solved;

step 5, galvanizing the household electrical board: the hard rolled coil of the previous procedure is cleaned, annealed, hot galvanized, leveled, passivated, oiled and the like by the hot galvanizing procedure, and the key control point of a hot galvanizing zinc pot is the aluminum content of the zinc pot, and the requirements are as follows: the aluminum content of the zinc pot is more than or equal to 0.18 percent and less than or equal to 0.22 percent, the target is 0.2 percent, and the finished galvanized household electric board is finally produced through the working procedures of off-line judgment, bundling, weighing, packaging, warehousing and the like. The effect of adjusting the aluminum content of the zinc pot is limited.

The above description is only for the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.