阅读说明：本技术 一种厚规格厚镀层锌铝镁带钢表面质量的控制方法 (Control method for surface quality of thick zinc-aluminum-magnesium strip steel with thick coating ) 是由 李建英 谭文振 姜嘉玮 王言峰 张斌 纪明龙 邵延泽 韩冰 池永清 于 2021-08-12 设计创作，主要内容包括：一种厚规格厚镀层锌铝镁带钢表面质量的控制方法,属于冶金技术领域。其包括：根据带钢的厚度调整带钢的入锅温度,根据带钢的厚度调节气刀刀唇与带钢之间的距离、气刀的压力；所述带钢的厚度为1.8～3.0mm,镀层双面厚度≥275g/m～(2),热浸镀工序中镀液温度为470～495℃。本发明通过锌铝镁生产线气刀工艺、镀锅的温度制度与镀层、带钢厚度之间的关联关系,摸索出一套适合生产不同厚度规格及镀层厚度的工艺参数使镀层横纹以及边部的结晶斜线得到很好的控制,很好的保证了产品的表面质量,且未对生产难度以及生产成本造成大的影响。(A method for controlling the surface quality of a thick zinc-aluminum-magnesium strip steel with a thick coating belongs to the technical field of metallurgy. It includes: adjusting the temperature of the strip steel entering the boiler according to the thickness of the strip steel, and adjusting the distance between the knife lip of the air knife and the strip steel and the pressure of the air knife according to the thickness of the strip steel; the thickness of the strip steel is 1.8-3.0mm, and the thickness of the two sides of the coating is more than or equal to 275g/m 2 And the temperature of the plating solution in the hot dip plating process is 470-495 ℃. According to the invention, a set of materials suitable for producing different thickness specifications is obtained through the correlation among the air knife process of the zinc-aluminum-magnesium production line, the temperature system of the plating pot, the thickness of the plating layer and the thickness of the strip steelAnd the technological parameters of the thickness of the plating layer enable the cross striations of the plating layer and the crystal oblique lines at the edge part to be well controlled, the surface quality of the product is well ensured, and large influence on the production difficulty and the production cost is not caused.)

1. A control method for the surface quality of a thick-specification thick-coating zinc-aluminum-magnesium strip steel is characterized by comprising the following steps:

adjusting the temperature of the strip steel entering the boiler according to the thickness of the strip steel;

adjusting technological parameters of the air knife according to the thickness of the strip steel, wherein the technological parameters comprise the distance between a knife lip of the air knife and the strip steel and the pressure of the air knife;

the thickness T of the strip steel is 1.8-3.0mm, and the thickness of the two sides of the coating is more than or equal to 275g/m²Temperature of plating solution in Hot Dip plating ProcessThe temperature is 470-495 ℃.

2. The method for controlling the surface quality of the thick zinc-aluminum-magnesium strip steel with the thick coating according to claim 1, wherein the plating solution in the hot dip plating process comprises the following components: al: 0.5-3.0wt%, Mg is less than or equal to 2.2wt%, Fe: 0.008 to 0.020wt%, and the balance of Zn and inevitable impurities.

3. The method for controlling the surface quality of the thick-specification and thick-coating zinc-aluminum-magnesium strip steel according to claim 2, wherein the step of adjusting the pan-in temperature of the strip steel according to the thickness of the strip steel comprises the following steps:

when T is more than or equal to 1.8mm and less than 2.2mm, the temperature of the strip steel in the boiler is 485 +/-5 ℃;

when T is more than or equal to 2.2mm and less than 2.6mm, the temperature of the strip steel in the pot is 475 +/-5 ℃;

when T is more than or equal to 2.6mm and less than or equal to 3.0mm, the temperature of the strip steel entering the pot is 465 +/-5 ℃.

4. The method for controlling the surface quality of the thick-specification thick-coating zinc-aluminum-magnesium strip steel according to claim 3, wherein the step of adjusting the distance between the knife lip of the air knife and the strip steel according to the thickness of the strip steel comprises the following steps:

when T is more than or equal to 1.8mm and less than 2.2mm, the distance between the knife lip of the air knife and the strip steel is 12-14 mm;

when T is more than or equal to 2.2mm and less than 2.6mm, the distance between the knife lip of the air knife and the strip steel is 10-12 mm;

when T is more than or equal to 2.6mm and less than or equal to 3.0mm, the distance between the knife lip of the air knife and the strip steel is 8-10 mm.

5. The method for controlling the surface quality of the thick-gauge zinc-aluminum-magnesium coated steel strip according to claim 4, wherein the step of adjusting the pressure of the air knife according to the thickness of the steel strip comprises the following steps:

when T is more than or equal to 1.8mm and less than 2.2mm, the pressure of the air knife is 120-150 mbar;

when T is more than or equal to 2.2mm and less than 2.6mm, the pressure of the air knife is 100-120 mbar;

when T is more than or equal to 2.6mm and less than or equal to 3.0mm, the pressure of the air knife is 80-100 mbar.

Technical Field

The invention belongs to the technical field of metallurgy, and particularly relates to a method for controlling the surface quality of thick-specification thick-coating zinc-aluminum-magnesium strip steel.

Background

The corrosion prevention of steel materials is a problem which always troubles the use of steel. In order to solve or reduce the corrosion problem of steel, various metal coatings have been developed. However, due to the limited use environment, the corrosion prevention problem is still the main problem of the steel material.

The zinc-aluminum-magnesium product has better corrosion resistance and unique trimming protection characteristic compared with a pure zinc product, and is widely used for manufacturing parts with high corrosion in working environments, in particular photovoltaic brackets, various rainwater pipelines, guardrails on roads and seasides and the like. The corrosion of the using environment is strong, and although the zinc-aluminum-magnesium product has good corrosion resistance, the thicker plating layer can meet the using requirement within a certain period. The steel plate is generally thick because it plays a certain supporting role. For steel plate manufacturers, the steel plate is thick, the production speed is low, the coating requirement is thick, the production line is required to be as fast as possible, and the production difficulty of the products is high. Generally, in order to ensure the processing and using performance, the lower production speed is adopted, so the surface quality is poorer.

Disclosure of Invention

In order to solve the technical problem, the invention provides a method for controlling the surface quality of thick-specification thick-coating zinc-aluminum-magnesium strip steel. The invention adopts the following technical scheme:

a control method for the surface quality of a thick-specification thick-coating zinc-aluminum-magnesium strip steel comprises the following steps: adjusting the temperature of the strip steel entering the boiler according to the thickness of the strip steel; adjusting technological parameters of the air knife according to the thickness of the strip steel, wherein the technological parameters comprise the distance between a knife lip of the air knife and the strip steel and the pressure of the air knife; the thickness T of the strip steel is 1.8-3.0mm, and the thickness of the two sides of the coating is more than or equal to 275g/m²And the temperature of the plating solution in the hot dip plating process is 470-495 ℃.

The plating solution in the hot dip plating process comprises the following components: al: 0.5-3.0wt%, Mg is less than or equal to 2.2wt%, Fe: 0.008 to 0.020wt%, and the balance of Zn and inevitable impurities.

The pot entering temperature of the strip steel is adjusted according to the thickness of the strip steel, and the pot entering temperature adjusting method comprises the following steps:

when T is more than or equal to 1.8mm and less than 2.2mm, the temperature of the strip steel in the boiler is 485 +/-5 ℃;

when T is more than or equal to 2.2mm and less than 2.6mm, the temperature of the strip steel in the pot is 475 +/-5 ℃;

when T is more than or equal to 2.6mm and less than or equal to 3.0mm, the temperature of the strip steel entering the pot is 465 +/-5 ℃.

The distance between the air knife lip and the strip steel is adjusted according to the thickness of the strip steel, and the method comprises the following steps:

when T is more than or equal to 1.8mm and less than 2.2mm, the distance between the knife lip of the air knife and the strip steel is 12-14 mm;

when T is more than or equal to 2.2mm and less than 2.6mm, the distance between the knife lip of the air knife and the strip steel is 10-12 mm;

when T is more than or equal to 2.6mm and less than or equal to 3.0mm, the distance between the knife lip of the air knife and the strip steel is 8-10 mm.

The adjusting of the pressure of the air knife according to the thickness of the strip steel includes:

when T is more than or equal to 1.8mm and less than 2.2mm, the pressure of the air knife is 120-150 mbar;

when T is more than or equal to 2.2mm and less than 2.6mm, the pressure of the air knife is 100-120 mbar;

when T is more than or equal to 2.6mm and less than or equal to 3.0mm, the pressure of the air knife is 80-100 mbar.

The invention is suitable for the thickness of strip steel of 1.8-3.0mm and the thickness of the two sides of a coating of 275g/m²And the low-aluminum low-magnesium coating component. The general steel plate with thick strip steel, low running speed and thick coating thickness has serious coating cross striation defects and edge crystallization oblique line defects on the surface of the steel plate, and is difficult to accept by customers. The invention mainly aims to control the amount of slag in the plating solution and ensure the surface quality of the plating layer. In order to ensure the sufficient fluidity of the plating solution, the temperature of the plating solution is increased to 470-495 ℃, and the temperature of the strip steel entering the pot is different by combining the different core heat of the strip steel with different thicknesses. According to the invention, a set of process parameters suitable for producing different thickness specifications and coating thicknesses are obtained by searching the incidence relation among the air knife process of the zinc-aluminum-magnesium production line, the temperature system of the plating pot, the coating and the strip steel thickness, so that the surface quality of the product is well ensured. The cross grain of the plating layer and the crystal oblique line of the edge part are well controlled, the surface quality of the strip steel product is greatly improved, and the production difficulty and the production cost are not greatly influenced.

Detailed Description

The present invention will be described in further detail with reference to examples.

The method for controlling the surface quality of the thick-specification thick-coating zinc-aluminum-magnesium strip steel is suitable for controlling the thickness T of 1.8-3.0mm and the thickness of the double surfaces of the coating to be more than or equal to 275g/m²The galvanized aluminum-magnesium strip steel. In the hot dip plating process, the temperature of the plating solution is 470-495 ℃, and the plating solution comprises the following components: al: 0.5-3.0wt%, Mg is less than or equal to 2.2wt%, Fe: 0.008 to 0.020wt%, and the balance of Zn and inevitable impurities. The method specifically comprises the following steps:

(1) adjusting the temperature of the strip steel entering the boiler according to the thickness of the strip steel:

when T is more than or equal to 1.8mm and less than 2.2mm, the temperature of the strip steel in the boiler is 485 +/-5 ℃;

when T is more than or equal to 2.2mm and less than 2.6mm, the temperature of the strip steel in the pot is 475 +/-5 ℃;

when T is more than or equal to 2.6mm and less than or equal to 3.0mm, the temperature of the strip steel entering the pot is 465 +/-5 ℃.

(2) Adjusting the distance between the air knife lip and the strip steel according to the thickness of the strip steel:

when T is more than or equal to 1.8mm and less than 2.2mm, the distance between the knife lip of the air knife and the strip steel is 12-14 mm;

when T is more than or equal to 2.2mm and less than 2.6mm, the distance between the knife lip of the air knife and the strip steel is 10-12 mm;

when T is more than or equal to 2.6mm and less than or equal to 3.0mm, the distance between the knife lip of the air knife and the strip steel is 8-10 mm.

(3) Adjusting the pressure of the air knife according to the thickness of the strip steel:

when T is more than or equal to 1.8mm and less than 2.2mm, the pressure of the air knife is 120-150 mbar;

when T is more than or equal to 2.2mm and less than 2.6mm, the pressure of the air knife is 100-120 mbar;

when T is more than or equal to 2.6mm and less than or equal to 3.0mm, the pressure of the air knife is 80-100 mbar.

Examples 1 to 13: the thickness of the strip steel and the plating layer, the plating solution components and the process control parameters are shown in the table below.

TABLE 1 thickness, bath composition, process control parameters for strip and coating of each example

The surface quality of the galvanized aluminum-magnesium strip steel product produced by the invention reaches FB level or above, no obvious zinc flow lines and edge crystallization lines exist on the surface, and the product percent of pass is 99.8%.