阅读说明：本技术 一种热镀铝锌钢板的生产方法 (Production method of hot-dip aluminum-zinc steel plate ) 是由 丁志龙 穆海玲 魏宝民 闫秉昊 于 2018-08-29 设计创作，主要内容包括：本发明公开了一种热镀铝锌钢板的生产方法,主要解决现有技术中热镀铝锌钢板镀层锌花尺寸大、锌花控制成本高的技术问题。本发明提供的热镀铝锌钢板的生产方法,包括以下步骤：冷轧轧硬带钢经卧式连续退火炉退火、热浸镀铝锌、镀后冷却、平整,卷取得到厚度为0.4～0.6mm成品热镀铝锌钢板；所述冷轧轧硬带钢的化学成分重量百分比为：C：0.02-0.08％,Si：0-0.05％,Mn：0.1-0.4％,P：0-0.015％,S：0-0.015％,Alt：0.015-0.05％,其余为Fe和不可避免夹杂；冷轧轧硬带钢表面粗糙度为0.8-1.5μm。本发明方法生产的热镀铝锌钢板镀层锌花为60-100个/100mm。(The invention discloses a production method of a hot-dip aluminum-zinc steel plate, which mainly solves the technical problems of large size of spangles and high spangle control cost of a coating of the hot-dip aluminum-zinc steel plate in the prior art. The invention provides a production method of a hot-dip aluminum-zinc steel plate, which comprises the following steps: annealing the cold-rolled hard strip steel through a horizontal continuous annealing furnace, hot-dipping aluminum and zinc, cooling and leveling after plating, and coiling to obtain a finished hot-dipped aluminum and zinc steel plate with the thickness of 0.4-0.6 mm; the cold-rolled hard strip steel comprises the following chemical components in percentage by weight: c: 0.02 to 0.08%, Si: 0-0.05%, Mn: 0.1-0.4%, P: 0-0.015%, S: 0-0.015%, Alt: 0.015-0.05%, the balance being Fe and inevitable impurities; the surface roughness of the cold-rolled hard strip steel is 0.8-1.5 mu m. The hot-dip aluminum-zinc plated steel plate produced by the method has 60-100 zinc spangles per 100 mm.)

1. The production method of the hot-dip aluminum-zinc steel plate is characterized by comprising the following steps of:

annealing the cold-rolled hard strip steel through a horizontal continuous annealing furnace, hot-dipping aluminum and zinc, cooling and leveling after plating, and coiling to obtain a finished hot-dipped aluminum and zinc steel plate with the thickness of 0.4-0.6 mm; the cold-rolled hard strip steel comprises the following chemical components in percentage by weight: c: 0.02 to 0.08%, Si: 0-0.05%, Mn: 0.1-0.4%, P: 0-0.015%, S: 0-0.015%, Alt: 0.015-0.05%, the balance being Fe and inevitable impurities; the surface roughness of the cold-rolled hard strip steel is 0.8-1.5 mu m, the tensile strength is more than 700MPa, and the thickness is 0.4-0.6 mm;

the annealing process comprises the steps that the temperature of a cold-rolled strip steel in a hard rolling state in a soaking section of annealing of a horizontal continuous annealing furnace is 730-780 ℃, and the annealing time of the strip steel in the soaking section is 28-40 s;

the hot-dip aluminum-zinc plating process comprises the steps that the temperature of strip steel entering a zinc pot is 600-610 ℃, the temperature of aluminum-zinc liquid in the zinc pot is 591-595 ℃, and the speed of the strip steel passing through the zinc pot is 90-130 m/min;

the post-plating cooling is three-stage cooling, the first stage cooling, the second stage cooling and the third stage cooling are all air cooling, the first stage cooling is to cool the hot-dip aluminum-zinc steel plate after passing through the air knife, the first stage cooling speed is 10-15 ℃/S, and the first stage cooling finishing temperature is 560-; the second section of cooling is to cool the hot-dip aluminum-zinc steel plate from 560-570 ℃ to 480-500 ℃, the second section of cooling speed is 30-50 ℃/S, and the second section of cooling finishing temperature is 480-500 ℃; the third section of cooling is to cool the hot-dip aluminum-zinc steel plate from 480 ℃ to 280 ℃ to 300 ℃, the third section of cooling speed is 15-25 ℃/S, and the third section of cooling finishing temperature is 280 ℃ to 300 ℃;

the flattening process comprises flattening elongation of 1.0-1.2%.

2. The method for producing the hot-dip aluminum-zinc steel plate as claimed in claim 1, wherein the aluminum-zinc liquid in the zinc pot comprises the following chemical components in percentage by weight: al: 50-60%, Si: 1.2-1.8%, La: 0.06-0.1 percent, and the balance of zinc and inevitable impurities.

3. The method for producing the hot-dip Al-Zn steel plate as claimed in claim 1, wherein the yield strength RP0.2, the tensile strength Rm and the elongation after fracture A of the hot-dip Al-Zn steel plate are 220-350MPa, 350-420MPa and_80mm30-36%; the coating spangles of the hot-dip aluminum-zinc steel plate are 60-100 per 100 mm.

Technical Field

The invention relates to a hot-dip aluminum-zinc steel plate, in particular to a production method of the hot-dip aluminum-zinc steel plate, and particularly relates to a method for controlling zinc flowers on a coating of the hot-dip aluminum-zinc steel plate, belonging to the technical field of continuous hot-dip aluminum-zinc steel plate manufacturing.

Background

The American Berley constant (Bethlehem) iron and steel company develops and develops an aluminum-zinc plated steel plate in 1964, and the aluminum content of an alloy coating is 55%, the zinc content is 43.5% (+ -0.5-1.0%) and the silicon content is 1.5% (+ -0.5%) so that the aluminum-zinc plated steel plate has the best corrosion resistance and service performance.

The hot-dip aluminum-zinc substrate has many excellent characteristics and thus has wide industrial applicability, and for example, the hot-dip aluminum-zinc substrate has good corrosion resistance due to a protective function of a plating layer (particularly, aluminum), and also has good heat resistance and heat reflectivity, and thus is widely used in the fields of buildings, automobiles, home appliances, and the like. So far, a great deal of research on aluminum and zinc is mainly to improve the corrosion resistance of the coating.

With the rapid development of the liquid crystal module industry and the electric appliance cabinet industry at home and abroad, smaller spangles have better aesthetic property, clear requirements are provided for spangles on the surface of a hot-dip aluminum-zinc steel plate, the number of the spangles is usually required to be more than or equal to 60/100 mm, and the spangles on the surface of the hot-dip aluminum-zinc steel plate in the prior art relate to a method for adding elements with more control parameters.

The Chinese patent document with application publication number CN106319416A discloses a method for controlling the spangle size of a hot-dip aluminum-zinc steel plate, and the production method comprises the steps of controlling an acid washing process, a rolling process and a hot-dip aluminum-zinc process. The conductivity and the temperature of the rinsing water are respectively within 50 mu s/m and below 70 ℃, and the acid inlet amount is between 2.0 and 3.5m 3/h; the oil concentration and the miscellaneous oil content of the rolling emulsion are respectively 1.5-3.0% and less than 18%, and the iron soap content in the rolling emulsion is within 0.5%; after an aluminum-zinc plating unit is cleaned, the residual oil content is controlled within 80mg/m2, the switching time of the high power and the low power of a zinc pot is controlled within 60min, and the titanium content is stably controlled to be 0.08-0.125 ppm of the plating solution amount.

Chinese patent application publication No. CN103849828A discloses a method for producing hot-dip aluminum-zinc strip steel, wherein the production method comprises sequentially annealing the substrate base material by using an annealing furnace and hot-dip aluminum-zinc alloy plating the substrate base material in a zinc pot, wherein the temperature of the substrate base material in the outlet section is 590-595 ℃, the temperature of the alloy liquid in the zinc pot is 595-605 ℃, which mainly provides a process method for producing thin gauge.

Disclosure of Invention

The invention aims to provide a production method of a hot-dip aluminum-zinc steel plate, which mainly solves the technical problems of large spangle size and high spangle control cost of a coating of the hot-dip aluminum-zinc steel plate in the prior art.

The technical idea of the invention is to control the size of the spangles of the coating of the hot-dip aluminum-zinc steel plate by scientifically designing the control parameters of the hot-dip process. The method is based on the following research to discover that the main reasons of the grain size of the coating of the aluminum-zinc plated steel plate are the components of the aluminum-zinc coating and the cooling process; after the steel plate is annealed, the steel plate enters zinc liquid at a certain temperature, interface reaction occurs between the steel plate and Al in the plating liquid, the degree of interface reaction is influenced by the pot-entering temperature of the steel plate, and the distribution of Fe at the interface is determined, so that conditions are provided for the solidification of a plating layer at the interface nucleation; the La trace element in the plating solution plays a role of a nucleating agent due to higher melting point. The cooling after plating plays a role in controlling the spangle nucleation, and particularly, the cooling speed ranging from the freezing point to 480 ℃ has obvious influence on the spangle.

The invention adopts the technical scheme that the production method of the hot-dip aluminum-zinc steel plate comprises the following steps:

annealing the cold-rolled hard strip steel through a horizontal continuous annealing furnace, hot-dipping aluminum and zinc, cooling and leveling after plating, and coiling to obtain a finished hot-dipped aluminum and zinc steel plate with the thickness of 0.4-0.6 mm; the cold-rolled hard strip steel comprises the following chemical components in percentage by weight: c: 0.02 to 0.08%, Si: 0-0.05%, Mn: 0.1-0.4%, P: 0-0.015%, S: 0-0.015%, Alt: 0.015-0.05%, the balance being Fe and inevitable impurities; the surface roughness of the cold-rolled hard strip steel is 0.8-1.5 mu m, the tensile strength is more than 700MPa, and the thickness is 0.4-0.6 mm;

the annealing process comprises the steps that the temperature of a cold-rolled strip steel in a hard rolling state in a soaking section of annealing of a horizontal continuous annealing furnace is 730-780 ℃, and the annealing time of the strip steel in the soaking section is 28-40 s;

the hot-dip aluminum-zinc plating process comprises the steps that the temperature of strip steel entering a zinc pot is 600-610 ℃, the temperature of aluminum-zinc liquid in the zinc pot is 591-595 ℃, and the speed of the strip steel passing through the zinc pot is 90-130 m/min;

the post-plating cooling is three-stage cooling, the first stage cooling, the second stage cooling and the third stage cooling are all air cooling, the first stage cooling is to cool the hot-dip aluminum-zinc steel plate after passing through the air knife, the first stage cooling speed is 10-15 ℃/S, and the first stage cooling finishing temperature is 560-; the second section of cooling is to cool the hot-dip aluminum-zinc steel plate from 560-570 ℃ to 480-500 ℃, the second section of cooling speed is 30-50 ℃/S, and the second section of cooling finishing temperature is 480-500 ℃; the third section of cooling is to cool the hot-dip aluminum-zinc steel plate from 480 ℃ to 280 ℃ to 300 ℃, the third section of cooling speed is 15-25 ℃/S, and the third section of cooling finishing temperature is 280 ℃ to 300 ℃;

the flattening process comprises flattening elongation of 1.0-1.2%.

Further, the aluminum-zinc liquid in the zinc pot comprises the following chemical components in percentage by weight: al: 50-60%, Si: 1.2-1.8%, La: 0.06-0.1 percent, and the balance of zinc and inevitable impurities.

The yield strength RP0 of the hot-dip aluminum-zinc plated steel plate produced by the method_.2220-350MPa, tensile strength R_m350-420MPa, and the elongation A80mm after fracture is 30-36%; the coating spangles of the hot-dip aluminum-zinc steel plate are 60-100 per 100 mm.

The production process adopted by the invention has the following reasons:

1. setting of annealing temperature and annealing time

In order to realize complete recrystallization in the annealing process, the recrystallization completion temperature in the chemical composition range is 700 ℃, so that in order to ensure the production reliability, the annealing temperature is 730-780 ℃; the annealing time is related to the recrystallization time of the material and the heating capacity of a machine set, the speed of strip steel in actual production is 90-130 m/min, and the time of a corresponding re-soaking period is 28-40 s.

2. Setting of hot-dip aluminum-zinc plating process parameters

The invention sets the chemical components of the aluminum-zinc liquid in the zinc pot in weight percentage as follows: al: 50-60%, Si: 1.2-1.8%, La: 0.06-0.1 percent of La, the balance of zinc and inevitable impurities, rare earth element La is added into the aluminum zinc liquid, the melting point is 921 ℃, the aluminum zinc liquid is in a simple substance state, meanwhile, the addition of the La element can increase the wettability of the steel plate and the plating liquid, and plays a good role of a nucleating agent in the solidification process of the plating layer, but the excessive addition can cause the enrichment of the La element to form a slag phase, so the addition amount of the La element is 0.06-0.1 percent; the Al content is set to be 50-60% according to the requirement of the corrosion resistance of the material; the Si content is usually determined according to the platability requirement, a certain amount of silicon is added, the bonding force between the plating layer and the substrate can be improved, and the set content is 1.2-1.8%.

The temperature of the substrate of the hot-dip aluminum-zinc steel plate is set when the substrate is put into a zinc pot, the iron in the substrate reacts with the aluminum in the zinc liquid after the substrate is put into the zinc liquid, the pot-entering temperature determines the reaction of the Fe in the steel plate and the Al in the plating solution, the high temperature can cause the thickening of an alloy layer, the performance of a plating layer is unfavorable, but the content of the iron at the interface of the plating layer is enriched, the nucleation of the interface is facilitated, the refining of the structure of the plating layer is facilitated, the reaction is insufficient when the pot-entering temperature is too low, the binding force is insufficient, the grain refining effect is not obvious, and the temperature of the substrate of the hot-dip aluminum-.

Setting the temperature of the zinc pot, wherein the reaction between the substrate and the zinc liquid is influenced by the temperature and is related to the temperature of the substrate and the temperature of the zinc liquid, and setting the temperature of the zinc pot 591-595 ℃ when the substrate of the hot dip coating aluminum-zinc steel plate is hot dipped by combining the capability and the actual surface quality of the zinc pot.

3. Setting of post-plating cooling process parameters

Cooling after plating is three-stage cooling, wherein the first stage cooling, the second stage cooling and the third stage cooling are all air cooling, the first stage cooling is to cool the hot-dip aluminum-zinc steel plate after passing through the air knife, the first stage cooling speed is 10-15 ℃/S, and the first stage cooling finishing temperature is 560-; since the galvanizing temperature is still in a liquid state, the size of the coating grains is not influenced, and the section generally belongs to a free cooling stage and is not controlled in actual production.

The second section of cooling is to cool the hot-dip aluminum-zinc steel plate from 560-570 ℃ to 480-500 ℃, the second section of cooling speed is 30-50 ℃/S, and the second section of cooling finishing temperature is 480-500 ℃; phase diagram calculation and tests show that the solidification starting temperature of the aluminum-rich phase of the aluminum-zinc liquid of the design component under the equilibrium condition is 556 ℃, the end temperature is 510 ℃, the actual solidification end temperature is reduced by 20-30 ℃, and experimental researches show that rapid cooling at 556 and 480 ℃ is beneficial to nucleation and has obvious refining effect on coating grains.

The third section of cooling is to cool the hot-dip aluminum-zinc steel plate from 480 ℃ to 280 ℃ to 300 ℃, the third section of cooling speed is 15-25 ℃/S, and the third section of cooling finishing temperature is 280 ℃ to 300 ℃; conditions are created for the solidification and nucleation of the coating through the components of the plating solution, the pot-entering temperature and the two-stage cooling process, and because the plating solution can release a large amount of latent heat in the solidification process and a large amount of nucleation points can be melted again in the solidification process, the continuity of the cooling of the coating is very important. Phase diagram calculation and experiment show that the solidification finishing temperature of the zinc-rich phase of the design composition under the equilibrium condition is 320 ℃.

The applicant researches and accumulates for many years to solve the industrial problem of controlling the grain size of the coating of the hot-dip aluminum-zinc steel plate, and provides a method for controlling the coating components and cooling after coating to solve the nucleation point when the coating is solidified so as to form fine grains. The invention solves the problem of the grain size of the plating layer by controlling the addition of trace elements of the components of the plating layer, the temperature of the hot-dip plating substrate when the substrate is put into a pot, the temperature of a zinc pot and the cooling speed of different sections after plating.

Compared with the prior art, the invention has the following positive effects: 1. the method solves the technical problem of grain refinement of the coating of the hot-dip aluminum-zinc product with the thickness of 0.4-0.6mm by adding trace elements in the hot-dip coating solution and controlling the process, achieves similar effect by adding titanium element and boron element in the prior art, but has the advantage that a large amount of TiAl cannot be generated in a zinc pot₃Mass points, thereby reducing the generation of a large amount of slag in the production process, being beneficial to the stable operation of the zinc pot, and avoiding the problems of low qualification rate and high production cost caused by quality defects in the production process. 2. The invention can realize the control of the grain size of the coating of the product by adjusting the air cooling speed, has flexible control method and convenient implementation, and brings beneficial effects to the surface quality of the coated steel plate, thereby obtaining the effects of smooth surface and uniform spangles. 3. The method generates a grain refining effect through rapid cooling, is a good method for obtaining uniform and consistent tissues, is favorable for improving the binding force of the plating layer and the steel substrate on the premise of ensuring the corrosion resistance of the plating layer, and effectively improves the processing reliability of materials.

Drawings

FIG. 1 is a photograph showing a metallographic structure of a plated layer of an Al-Zn hot-dipped steel sheet according to example 2 of the present invention.

FIG. 2 is a photograph showing the appearance of fine spangles on the surface of a coating layer of a hot-dip aluminum-zinc coated steel sheet according to example 2 of the present invention.

Detailed Description

The invention is further illustrated below with reference to examples 1 to 6. Table 1 shows the chemical composition (in weight percent) of the substrate of the hot-dip aluminum-zinc coated steel sheet according to the embodiment of the present invention, and the balance Fe and inevitable impurities.

Table 1 chemical composition of substrate of hot-dip aluminum-zinc coated steel sheet of example of the present invention, unit: and (4) weight percentage.

Element(s)	C	Si	Mn	P	S	Alt
							The invention	0.02-0.08	0-0.05	0.1-0.4	0-0.015	0-0.015	0.015-0.05
Example 1	0.03	0.03	0.2	0.010	0.015	0.030
							Example 2	0.05	0.05	0.3	0.014	0.014	0.015
Example 3	0.02	0.03	0.1	0.012	0.013	0.050
							Example 4	0.08	0.04	0.4	0.015	0.010	0.015
Example 5	0.07	0.03	0.3	0.010	0.009	0.020
							Example 6	0.055	0.02	0.3	0.011	0.013	0.026

Annealing the rolled hard steel strip with the surface roughness of 0.8-1.5 mu m and the tensile strength of more than 700MPa by a horizontal continuous annealing furnace, hot-dipping aluminum and zinc, cooling in three sections after plating, flattening, and coiling to obtain a finished hot-dipped aluminum and zinc steel plate with the thickness of 0.4-0.6 mm. The annealing process comprises the following steps: the temperature of the soaking section of the commercial strip steel annealed in the horizontal continuous annealing furnace is 730-780 ℃, the annealing time of the strip steel in the soaking section is 28-40s, and the flat elongation is 1.0-1.2%. The control parameters of the annealing, hot-dip aluminum-zinc plating, cooling after plating and flattening process are shown in table 2.

TABLE 2 control parameters of annealing, hot-dip aluminizing and galvanizing, post-plating cooling and leveling processes according to the examples of the present invention

Table 3 shows that the aluminum-zinc liquid in the zinc pot of the embodiment of the invention comprises the following chemical components in percentage by weight: al: 50-60%, Si: 1.2-1.8%, La: 0.06-0.1 percent, and the balance of zinc and inevitable impurities.

Table 3 chemical composition of the aluminum-zinc liquid in the zinc pot of the embodiment of the present invention, unit: weight percent of

Element(s)	Al	Si	La
				The invention	50-60	1.2-1.8	0.06-0.10
Example 1	58	1.6	0.08
				Example 2	52	1.7	0.1
Example 3	60	1.2	0.06
				Example 4	55	1.5	0.07
Example 5	50	1.8	0.05
				Example 6	58	1.6	0.08

TABLE 4 parameters of spangles in the coating of hot-dip aluminum-zinc coated steel sheets according to the examples of the present invention

Categories	Thickness/mm of hot-dip aluminum-zinc steel plate	Spangles/number/100 mm
			The invention	0.4-0.6	60-100
Example 1	0.4	71
			Example 2	0.45	83
Example 3	0.6	60
			Example 4	0.5	94
Example 5	0.55	100
			Example 6	0.48	78

Referring to fig. 1, the metallographic structure of the coating of the hot-dip aluminum-zinc coated steel sheet obtained by the method comprises an aluminum-rich phase, a zinc-rich phase, a silicon phase and a rare earth phase; referring to fig. 2, the surface of the hot-dip aluminum-zinc steel plate coating forms fine spangles, the number of spangles on the surface of the hot-dip aluminum-zinc steel plate coating is 83/100 mm, and the spangles on the surface of the steel plate are fine, uniform and beautiful; yield strength R of hot-dip aluminum-zinc steel plate_P0.2220-350MPa, tensile strength R_m350-420MPa, elongation after fracture A_80mmIs 30-36%.

In addition to the above embodiments, the present invention may have other embodiments. All technical solutions formed by adopting equivalent substitutions or equivalent transformations fall within the protection scope of the claims of the present invention.