CN113817949A - Manufacturing method of 230 MPa-grade high-grade computer case plate - Google Patents

Abstract

The invention discloses a manufacturing method of a 230 MPa-grade high-grade computer case plate, which comprises the steps of strictly controlling C, N content, formulating a reasonable process, carrying out chromium-free fingerprint-resistant passivation treatment on the surface of strip steel, ensuring that a computer case has certain strength (pit resistance and drop resistance), realizing that the yield strength of a finished product is 230-270 MPa, the tensile strength is controlled at 310-360 MPa, the elongation rate reaches 35-45%, and meanwhile, the product has good corrosion resistance (the corrosion resistance area in 72 hours is less than or equal to 5%), fingerprint resistance, humidity and heat resistance, high temperature resistance, low surface resistance (the surface resistance is less than or equal to 1m omega) and good coating performance, so that the product meets the processing requirements of the computer case.

Description

Manufacturing method of 230 MPa-grade high-grade computer case plate

Technical Field

The invention relates to the field of research and development of special steel products, in particular to a manufacturing method of a 230 MPa-grade computer case plate.

Background

With the rapid upgrade of electronic products, hot-dip galvanized fingerprint-resistant steel sheets are favored by users due to their advantages of excellent fingerprint resistance, corrosion resistance, high temperature resistance, humidity resistance, good conductivity, good coating property, and the like. The high-grade computer case is required to have certain strength and simultaneously has the requirements of pit resistance, falling resistance and dust resistance. In order to achieve the indexes, the design idea of low-carbon aluminum killed steel is adopted, and the strip steel surface treatment agent in the galvanizing procedure adopts Shanghai Paka fingerprint-resistant agent. Reasonable process control is added to meet the requirements of high-grade computer cases, the steel is a product with stamping performance and certain formability, the steel accords with the development and design concept of steel for the high-grade computer cases, the steel has high technical content, and the production difficulty is higher.

The prior documents and patents are studied as follows:

the search literature, the development of the galvanized fingerprint-resistant steel plate made of Bao steel and the application of the galvanized fingerprint-resistant steel plate in the electronic industry, writes the development process of the galvanized fingerprint-resistant steel plate made of Bao steel and the application of the galvanized fingerprint-resistant steel plate in the aspect of computer cases.

The search patent 'development and development of color plates for computer cases' mainly explains the development and development of color-coated plates, and has high production cost.

The composition and physical properties of the surface treating agent in the galvanizing procedure, the performance of the chromium-free fingerprint-resistant film and the surface quality control technology of the strip steel are explained in the retrieval literature 'development of chromium-free fingerprint-resistant galvanized steel plates for household appliances'.

Disclosure of Invention

The invention aims to provide a manufacturing method of a 230 MPa-grade high-grade computer case board, which solves the problem.

In order to solve the technical problems, the invention adopts the following technical scheme:

the invention relates to a manufacturing method of a 230 MPa-grade computer case board, which comprises the following steps:

the steel-making process comprises the following steps: KR desulfurization → converter → RH refining → slab casting;

the hot rolling process comprises the following steps: heating furnace → rough rolling high pressure water descaler → fixed width press → E1R1 rough rolling mill → E2R2 rough rolling mill → heat preservation cover → flying shear → finish rolling high pressure water descaler → F1-F7 finishing mill → encrypted laminar cooling → coiler; the heating temperature of the plate blank is 1180-1220 ℃, the finish rolling temperature is 875-905 ℃, and the coiling temperature is 665-695 ℃;

acid rolling process: acid rolling and uncoiling → welding → straightening → acid washing → rinsing → drying → trimming → rolling → coiling → acid rolling reduction rate is more than or equal to 70%;

and (3) a galvanizing process: hot galvanizing decoiling → welding → inlet loop → cleaning → annealing furnace → zinc pot → cooling after plating → water quenching → middle loop → finishing machine → straightening machine → roller coater → drying machine → air cooling device → outlet loop → trimming → surface inspection → oil coating → sampling → coiling; the outlet temperature of a galvanizing annealing/soaking section is 750-780 ℃, the outlet temperature of a slow cooling section is 670-690 ℃, the elongation of a leveler is 1.0-1.20%, the elongation of a tension leveler is 0.15-0.25%, and the production line speed is 90-130 m/min; the roller coater adopts reverse coating, the pressure of a coating roller is more than or equal to 100kgf, and the pressure of a dipping roller is more than or equal to 150 kgf.

Furthermore, in order to achieve the desired mechanical property index, the chemical components are as follows: less than or equal to 0.05 percent of C, less than or equal to 0.02 percent of Si, less than or equal to 0.3 percent of Mn which is more than or equal to 0.15 percent, less than or equal to 0.02 percent of P, less than or equal to 0.015 percent of S, more than or equal to 0.020 percent of Alt, and less than or equal to 0.0050 percent of N; the balance of Fe and inevitable impurities.

Furthermore, the KR desulfurization procedure requires that the sulfur content of the molten iron fed into the converter is less than 0.005 percent, and the slag removing area of the molten iron is more than 95 percent.

Further, the control of the end point of the converter requires that the tapping temperature is more than or equal to 1660 ℃, normal turnover ladles are used for tapping, and the tapping temperature drop is required to be less than 70 ℃; adding a top slag modifier according to the oxygen content and the slag amount of the molten steel.

Further, carrying out decarburization treatment according to the in-place components and the temperature of RH molten steel supplied by the converter; after the decarburization is finished, adding aluminum particles for deoxidation according to the oxygen determination condition, and adding alloy such as ferromanganese and the like after the deoxidation is finished to adjust the components of the molten steel to a target value;

the casting machine in the continuous casting process is controlled by adopting a constant drawing speed, and the drawing speed range is 1.0-1.8 m/min; the nitrogen increasing amount in the continuous casting process is required to be less than 5 ppm.

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

according to the chemical components, the hot rolling process, the acid rolling process and the galvanizing process, the steel strip which has good stability of mechanical performance, good corrosion resistance, fingerprint resistance, high temperature resistance and other indexes and meets the use requirements of high-grade computer cases and large-scale servers can be manufactured.

The invention relates to the development of hot galvanizing fingerprint resistant plate, which is designed and developed from the whole flow of chemical components, smelting, hot rolling, cold rolling and hot galvanizing processes, and the development process is elaborated by the perfection of a comparison system. Not only has low production cost, but also meets the environmental protection requirements of international ROSH and Reach. The yield strength is controlled to be 230-270 MPa, the tensile strength is controlled to be 310-360 MPa, the elongation rate reaches 35% -45%, and the phenomena of cracking and the like in the process of punching the computer case due to large performance fluctuation are effectively avoided.

Drawings

The invention is further illustrated in the following description with reference to the drawings.

FIG. 1 is a structural diagram of a high-grade computer case board manufactured by the present invention;

FIG. 2 is a photograph of a 72 hour salt spray corrosion;

FIG. 3 shows the results of the wet heat and humidity resistance test, wherein the left side is a single sheet and the right side is a laminate;

FIG. 4 shows the results of coating performance tests, in which the amino alkyd coating is on the left, the Acksol polyester powder coating is in the middle, and the chromium-free colored paint is on the right;

FIG. 5 is a test picture after being pressed with a finger;

Detailed Description

A manufacturing method of a 230 MPa-grade high-grade computer case plate comprises the following steps:

smelting process

KR desulfurization step: the sulfur content of the molten iron fed into the converter is required to be less than 0.005%, and the slag-removing area of the molten iron is required to be more than 95% (the surface of the molten iron after slag removal is cleaner).

A converter smelting process: the control requirements of the converter end point are as follows: the tapping temperature is more than or equal to 1660 ℃, normal turnover ladles are used for tapping, and the tapping temperature drop requirement is less than 70 ℃. Adding a top slag modifier according to the oxygen content and the slag amount of the molten steel.

RH process: and carrying out decarburization treatment according to the in-place components and the temperature of RH molten steel supplied by the converter. After the decarburization is finished, aluminum particles are added for deoxidation according to the oxygen determination condition, and after the deoxidation is finished, alloy such as ferromanganese is added to adjust the molten steel components to a target value.

And (3) continuous casting process: the casting machine is controlled by adopting a constant drawing speed, and the drawing speed range is 1.0-1.8 m/min; the nitrogen increasing amount in the continuous casting process is required to be less than 5 ppm.

Hot rolling process

A step-type heating furnace is adopted to heat a casting blank (the heating process is shown in table 1), a 3+3 mode is adopted for rough rolling, the finish rolling temperature is 875-905 ℃, the coiling temperature is 665-695 ℃, and the specific hot rolling process is shown in table 2.

TABLE 1 casting blank heating System

TABLE 2 Rolling Process

The control conditions of the outlet temperature of each section of the galvanizing annealing furnace are shown in Table 3, and the elongation rates of the leveler and the withdrawal and straightening unit are set in Table 4.

TABLE 3 annealing Process

TABLE 4 temper mill, withdrawal and straightening machine process

Examples analysis

Steelmaking compositions

The actual slab chemical composition (mass%) is shown in table 5 according to the above steelmaking process requirements.

Table 5 example chemical composition wt. -%)

Mechanical properties

The tensile mechanical properties at room temperature of the finished product are shown in Table 6, the yield and tensile strength of the product are stable, the user allowable range is 50MPa, the fluctuation range of the product manufactured according to the invention is less than 40MPa, the metallographic structure is ferrite and a small amount of pearlite, and the structure morphology is shown in figure 1.

TABLE 6 tensile Properties of the finished product

Salt spray performance

The neutral salt spray corrosion test results of the product are shown in table 7 and figure 2, the salt spray test can meet the requirement that the corrosion area is less than or equal to 5 percent in 72 hours, and the requirements of users and markets are met.

Table 7 neutral salt spray test results

Surface resistance

In order to ensure that the electronic and electric appliance shells have good antistatic performance, manufacturers generally require that the surface resistance of fingerprint-resistant products is less than 1m omega, the result of the surface resistance of fingerprint-resistant plates is shown in table 8, and test results show that the antistatic performance and the conductive performance of each fingerprint-resistant plate can meet the requirements.

TABLE 8 surface resistance at various positions

Resistance to humidity, heat and high temperature

And (3) placing the sample plate in a constant temperature and humidity box with the temperature of 150 ℃ and the humidity of 95% in a single-piece and laminated mode, taking out and drying after 120h, observing the surface condition of the sample plate, and measuring the color difference change before and after single-piece and laminated. The results of the humidity and heat resistance and high temperature resistance tests and the appearance are shown in table 9 and fig. 2, and after the single-piece/laminated plate is subjected to humidity and heat, the plate surface color difference of the passivated plate meets the requirements and is free of white rust.

TABLE 9 Damp and Heat test

Coating performance

The sample is cleaned by the degreasing agent at normal temperature, washed and dried, and then is respectively coated with the amino alkyd resin coating, the aksu polyester powder coating and the chromium-free color paint, so that the binding force between the fingerprint-resistant plate and the amino alkyd resin, the aksu polyester powder and the chromium-free color paint is good, the coating does not fall off in a Baige test, the coating is 100 percent qualified, and the test result and the appearance are shown in table 10 and figure 4.

TABLE 10 coating Properties

Fingerprint resistance

The sample was degreased at 50 ℃ and easily immersed for 1min, then immersed in a silane bath solution at 40 ℃ for 3min, washed with water and dried, and then pressed with a finger, so that no finger mark remained on the surface, as shown in table 11 and fig. 5.

TABLE 11 fingerprint resistance

Situation of use

The product manufactured according to the invention has good stamping condition after being processed by users and parts thereof.

According to the invention, a reasonable process is formulated by strictly controlling C, N content, and chromium-free fingerprint-resistant passivation treatment is carried out on the surface of strip steel, so that the computer case is ensured to have certain strength (pit resistance and drop resistance), the yield strength of a finished product is controlled to be 230-270 MPa, the tensile strength is controlled to be 310-360 MPa, the elongation reaches 35% -45%, and meanwhile, the computer case has good corrosion resistance (the corrosion resistance area is less than or equal to 5% in 72 hours), fingerprint resistance, humidity and heat resistance, high temperature resistance, low surface resistance (the surface resistance is less than or equal to 1m omega) and good coating performance, so that the product meets the processing requirements of the computer case.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.

Claims (5)

1. A manufacturing method of a 230 MPa-grade high-grade computer case board is characterized by comprising the following steps:

the steel-making process comprises the following steps: KR desulfurization → converter → RH refining → slab casting;

the hot rolling process comprises the following steps: heating furnace → rough rolling high pressure water descaler → fixed width press → E1R1 rough rolling mill → E2R2 rough rolling mill → heat preservation cover → flying shear → finish rolling high pressure water descaler → F1-F7 finishing mill → encrypted laminar cooling → coiler; the heating temperature of the plate blank is 1180-1220 ℃, the finish rolling temperature is 875-905 ℃, and the coiling temperature is 665-695 ℃;

acid rolling process: acid rolling and uncoiling → welding → straightening → acid washing → rinsing → drying → trimming → rolling → coiling → acid rolling reduction rate is more than or equal to 70%;

and (3) a galvanizing process: hot galvanizing decoiling → welding → inlet loop → cleaning → annealing furnace → zinc pot → cooling after plating → water quenching → middle loop → finishing machine → straightening machine → roller coater → drying machine → air cooling device → outlet loop → trimming → surface inspection → oil coating → sampling → coiling; the outlet temperature of a galvanizing annealing/soaking section is 750-780 ℃, the outlet temperature of a slow cooling section is 670-690 ℃, the elongation of a leveler is 1.0-1.20%, the elongation of a tension leveler is 0.15-0.25%, and the production line speed is 90-130 m/min; the roller coater adopts reverse coating, the pressure of a coating roller is more than or equal to 100kgf, and the pressure of a dipping roller is more than or equal to 150 kgf.

2. The method for manufacturing a 230 MPa-level high-grade computer case board according to claim 1, wherein: in order to achieve the expected mechanical property index, the chemical components are as follows: less than or equal to 0.05 percent of C, less than or equal to 0.02 percent of Si, less than or equal to 0.3 percent of Mn which is more than or equal to 0.15 percent, less than or equal to 0.02 percent of P, less than or equal to 0.015 percent of S, more than or equal to 0.020 percent of Alt, and less than or equal to 0.0050 percent of N; the balance of Fe and inevitable impurities.

3. The method for manufacturing a 230 MPa-level high-grade computer case board according to claim 1, wherein: the KR desulfurization procedure requires that the sulfur content of the molten iron fed into the converter is less than 0.005 percent, and the slag-off area of the molten iron is more than 95 percent.

4. The method for manufacturing a 230 MPa-level high-grade computer case board according to claim 1, wherein: the tapping temperature is required to be more than or equal to 1660 ℃ by the control of the converter end point, normal turnover ladles are used for tapping, and the tapping temperature drop is required to be less than 70 ℃; adding a top slag modifier according to the oxygen content and the slag amount of the molten steel.

5. The method for manufacturing a 230 MPa-level high-grade computer case board according to claim 1, wherein: carrying out decarburization treatment according to the in-place components and the temperature of RH molten steel supplied by the converter; after the decarburization is finished, adding aluminum particles for deoxidation according to the oxygen determination condition, and adding alloy such as ferromanganese and the like after the deoxidation is finished to adjust the components of the molten steel to a target value;

the casting machine in the continuous casting process is controlled by adopting a constant drawing speed, and the drawing speed range is 1.0-1.8 m/min; the nitrogen increasing amount in the continuous casting process is required to be less than 5 ppm.

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