KR101388364B1 - High corrosion resistant galvannealed steel sheet with excellent surface property and method for manufacturing the steel sheet - Google Patents

Abstract

A high corrosion resistant hot dip zinc alloy plated steel sheet having excellent surface characteristics, a method for manufacturing the same, and a hot dip zinc alloy plating solution for producing the same are disclosed.
In the hot-dip zinc alloy plated steel sheet according to the present invention, a hot-dip zinc alloy plated layer is formed on the surface of the base steel sheet, and the hot-dip zinc alloy plated layer is in weight%, magnesium (Mg): 0.5-2.0%, aluminum (Al): 1.0- 3.0%, misch metal (misch metal): characterized in that consisting of 0.02 ~ 0.5% and the remaining zinc (Zn).

Description

High corrosion resistance hot dip zinc alloy plated steel sheet with excellent surface properties and manufacturing method thereof {HIGH CORROSION RESISTANT GALVANNEALED STEEL SHEET WITH EXCELLENT SURFACE PROPERTY AND METHOD FOR MANUFACTURING THE STEEL SHEET}

The present invention relates to a hot-dip zinc alloy plated steel sheet manufacturing technology used in automobile exterior panels, and more particularly, to a hot-dip zinc alloy plated steel sheet having excellent corrosion resistance and excellent surface properties, a method of manufacturing the same, and a hot-dip zinc alloy plating solution for producing the same. It is about.

In the case of automotive exterior steel sheets, high corrosion resistance and high surface quality are required.

In the case of high strength, it is achieved through control of components or control of process conditions at the time of steel sheet production.

In the case of corrosion resistance, it is mainly achieved through hot dip zinc alloy plating. In the case of the hot-dip zinc alloy plating, it can greatly contribute to improving the corrosion resistance of the steel sheet, there is a problem that the surface quality is not very good, many researches for improving this.

Background art related to the present invention is a hot-dip galvanized steel sheet, an alloyed hot-dip galvanized steel sheet and a manufacturing method thereof having excellent surface quality disclosed in Republic of Korea Patent Publication No. 10-2009-0016852 (2009.02.18. Publication).

It is an object of the present invention to provide a hot-dip zinc alloy plated steel sheet having excellent corrosion resistance and excellent surface properties through plating layer composition control.

Another object of the present invention is to provide a method for producing a hot-dip zinc alloy plated steel sheet excellent in corrosion resistance and surface properties.

Still another object of the present invention is to provide a hot dip zinc alloy plating solution used for producing a hot dip galvanized steel sheet having excellent corrosion resistance and surface properties.

Hot-dip zinc alloy plated steel sheet according to an embodiment of the present invention for achieving the above object is a hot-dip zinc alloy plated layer is formed on the surface of the base steel sheet, the hot-dip zinc alloy plated layer by weight, magnesium (Mg): 0.5 2.0%, aluminum (Al): 1.0 to 3.0%, and a misch metal (misch metal): 0.02 to 0.5% and the remaining zinc (Zn) is characterized in that it consists of.

In this case, the molten zinc alloy plating layer may further include silicon (Si): 0.02 ~ 1.0% by weight.

Method for producing a molten zinc alloy plated steel sheet according to an embodiment of the present invention for achieving the above another object is (a) wt%, magnesium (Mg): 0.5 ~ 2.0%, aluminum (Al): 1.0 ~ 3.0%, Misch Metal: preparing a molten zinc alloy plating solution consisting of 0.02 ~ 0.5% and the remaining zinc (Zn); And (b) continuously immersing the base steel sheet in the molten zinc alloy plating solution to form a plating layer on the surface of the base steel sheet.

In this case, the molten zinc alloy plating solution may further include silicon (Si): 0.02 ~ 1.0% by weight.

In addition, in the step (b), it is preferable to maintain the temperature of the molten zinc alloy plating solution at 430 ~ 480 ℃.

Hot-dip zinc alloy plating solution according to an embodiment of the present invention for achieving the above another object by weight, magnesium (Mg): 0.5 ~ 2.0%, aluminum (Al): 1.0 ~ 3.0%, Misch metal: 0.02 ~ 0.5 It is characterized by consisting of% and the remaining zinc (Zn).

In this case, the molten zinc alloy plating solution may further include silicon (Si): 0.02 ~ 1.0% by weight.

Hot-dip zinc alloy plated steel sheet according to the present invention has excellent corrosion resistance by the hot-dip zinc alloy plating layer.

In particular, the hot-dip zinc alloy plated steel sheet according to the present invention exhibited a smooth surface and glossiness as a result of containing 0.02-0.5% by weight of a misch metal in the hot-dip zinc alloy plated layer.

Figure 1 schematically shows a hot-dip zinc alloy plated steel sheet according to the present invention.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described in detail below. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

Hereinafter, with reference to the accompanying drawings, it will be described in detail with respect to the high corrosion-resistant hot-dip zinc alloy plated steel sheet having excellent surface properties according to the present invention, a manufacturing method and a hot-dip zinc alloy plating solution for producing the same.

Figure 1 schematically shows a hot-dip zinc alloy plated steel sheet according to the present invention.

Referring to FIG. 1, the illustrated hot-dip zinc alloy plated steel sheet 100 includes a base steel plate 110 and a hot-dip zinc alloy plated layer 120.

The base steel sheet 110 may be a hot rolled steel sheet manufactured by slab reheating, hot rolling, and cooling / rolling. In addition, the base steel sheet 110 may be a cold rolled steel sheet produced by the process of pickling, cold rolling and annealing the hot rolled steel sheet.

The hot-dip zinc alloy plating layer 120 is formed on the surface of the base steel sheet 110.

At this time, the hot-dip zinc alloy plating layer 120 in weight%, magnesium (Mg): 0.5 ~ 2.0%, aluminum (Al): 1.0 ~ 3.0%, misch metal: 0.02 ~ 0.5% and the remaining zinc (Zn) )

In addition, the molten zinc alloy plating layer 120 may further include 0.02 to 1.0% by weight of silicon (Si).

Hereinafter, the role and content of each component included in the molten zinc alloy plating layer 120 will be described.

Magnesium (Mg)

Magnesium (Mg) Contributes to improving corrosion resistance.

The magnesium is preferably added in 0.5 to 2.0% by weight of the total weight of the plating layer. When the addition amount of magnesium is less than 0.5% by weight, the addition effect is insufficient. On the contrary, when the addition amount of magnesium exceeds 2 weight%, it causes a dross generation of a plating liquid.

Aluminum (Al)

Aluminum (Al) contributes to improvement in corrosion resistance and also contributes to suppressing the formation of dross in the plating liquid.

The aluminum (Al) is preferably added at 1.0 to 3.0% by weight of the total weight of the plating liquid. When the addition amount of aluminum is less than 1.0 weight%, the addition effect is inadequate. On the contrary, when the addition amount of aluminum exceeds 3.0 weight%, there exists a problem that weldability falls.

Misch metal

Mish Metal is a rare earth metal mixture prepared from ores such as Monazite, Bastnaesite and the like. Such a mesh metal is mainly composed of cerium (Ce), and includes lanthanum (La), neodymium (Nd), praseodymium (Pr), and the like.

In the present invention, the mesh metal refines the crystal grains of the primary Al-FCC phase in the Zn-Mg-Al three-way process to smooth the surface of the hot-dip zinc alloy plated steel sheet and improve the glossiness.

The mesh metal is preferably added at 0.02 to 0.5% by weight of the total weight of the plating liquid. It is possible to sufficiently improve the surface characteristics of the hot-dip zinc alloy plated steel sheet while suppressing the dross generation of the plating liquid in the addition range of the above-mentioned mesh metal.

When the added amount of the misch metal is less than 0.02% by weight, the improvement of the surface properties due to the addition of the misch metal may be insufficient. On the contrary, when the addition amount of the miscellaneous metal exceeds 0.5% by weight, the mismetal may cause dross in the plating solution, which may rather hinder the surface characteristics of the molten zinc alloy plated steel sheet.

Silicon (Si)

Silicon (Si) may be added to suppress the growth of the Fe—Zn or Fe—Al alloy layer of the hot dip zinc alloy plating layer and to improve plating adhesion.

When the silicon is added, the amount is preferably limited to 0.02 ~ 1.0% by weight of the total weight of the plating liquid. When the amount of silicon added is less than 0.02% by weight, not only is it insufficient to suppress the growth of the Fe alloy layer, but also does not contribute to the improvement of the corrosion resistance. On the other hand, when the addition amount of silicon exceeds 1.0% by weight, the solid solution in the zinc solid phase is out of the solution may be a peeling of the plating layer by a press or other processing process.

As for the molten zinc alloy plating layer 120 which consists of the said composition, it is more preferable that it is formed in thickness of 3-25 micrometers. In order to adjust the thickness of the hot-dip zinc alloy plating layer, an air knife or the like may be used.

When the thickness of the hot-dip zinc alloy plating layer is less than 3 μm, it may be difficult to ensure sufficient sacrificial corrosion resistance. On the contrary, when the thickness of the hot-dip zinc alloy plating layer is more than 25 μm, the anticorrosive period in which the base metal can be sacrificed is further extended, but the steel sheet manufacturing cost may increase.

The hot-dip zinc alloy plated steel sheet according to the present invention may be manufactured by a process including a hot-dip zinc alloy plating solution preparing step and a plating layer forming step.

In the molten zinc alloy plating solution preparing step, a molten zinc alloy plating solution having the above-described composition is prepared.

Next, in the plating layer forming step, the base steel sheet is continuously immersed in the molten zinc alloy plating liquid to form a plating layer on the surface of the base steel sheet. At this time, the plating liquid is preferably maintained at a temperature of 430 ~ 480 ℃. When the plating solution temperature is less than 430 ° C. during plating, the plating solution may be insufficient in fluidity of the plating solution and thus it may be difficult to form a plating layer on the surface of the base steel sheet sufficiently. On the contrary, when the temperature of the plating liquid exceeds 480 ° C during plating, the plating adhesion may be reduced.

Example

Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

Details that are not described herein will be omitted since those skilled in the art can sufficiently infer technically.

1. Fabrication of hot-dip zinc alloy plated steel sheet

After preparing the plating liquids according to Examples 1 to 3 and Comparative Examples 1 to 3 having the compositions shown in Table 1, the cold rolled steel sheets were immersed in the state where each plating liquid was maintained at 470 ° C. to form a plating layer having a thickness of 10 μm. To prepare a molten zinc alloy plated steel sheet.

[Table 1] (unit:% by weight)

2. Property evaluation method

(1) Evaluation of corrosion resistance

Corrosion resistance was measured by spraying brine continuously on the surface of the plated steel sheet prepared using the plating solution according to Examples 1 to 3 and Comparative Examples 1 to 3 according to the method specified in ASTM B117 to reduce the resistance time until the formation of red blue Evaluation was made based on the criteria.

○: 1000 hours or more

△: 500 hours or more, less than 1000 hours

X: less than 500 hours

(2) Evaluation of adhesion

The adhesion was evaluated by pressing with a flange or a cup according to the pullout test method defined in KS D0254 to generate metal parts and plated partial deformation, and then observing the peeling of the plating layer.

◎: No peeling of the plating layer (excellent)

○: Fine peeling of the plating layer (excellent)

(Triangle | delta): Peeling of a plating layer a little generate | occur | produces (usually)

X: Peeling occurrence of all plating layers (defect)

(3) Surface roughness

Surface roughness was measured using the SURFTEST (Mitutoyo, Japan) to measure the average roughness (Ra) of the plated steel sheet produced using the plating solution according to Examples 1 to 3 and Comparative Examples 1 to 3.

(4) glossiness

Glossiness was plated using a plating solution according to Examples 1 to 3 and Comparative Examples 1 to 3 at an incident angle of 60 ° using a glossmeter (Tri-Microgloss-20-60-85, Sheen Instruments Ltd., England). The glossiness of the steel sheet was measured.

3. Results of physical property evaluation

Table 2 shows the results of evaluation of physical properties of the molten zinc alloy plated steel sheet manufactured using the plating solutions according to Examples 1 to 3 and Comparative Examples 1 to 3.

[Table 2]

Referring to Table 2, in the case of the hot-dip zinc alloy plated steel sheet prepared using the plating solution according to Examples 1 to 3, the corrosion resistance and adhesion was excellent, the surface roughness is 1.0㎛ or less and the glossiness is 200 or more Comparative Example It was remarkably superior to 1-2.

On the other hand, in the case of the hot-dip zinc alloy plated steel sheet prepared using the plating solution according to Comparative Examples 1 to 2 without the addition of the miss metal or the trace amount, the corrosion resistance and adhesion were excellent, but the surface roughness was higher than those of the Examples 1 to 3 And glossiness was poor.

In addition, in the case of the hot-dip zinc alloy plated steel sheet manufactured using the plating solution according to Comparative Example 3 in which the miss metal was over-added, the gloss was excellent, but the surface roughness was not good.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Accordingly, the true scope of protection of the present invention should be defined by the claims.

100: hot dip zinc alloy plated steel sheet
110: base steel plate
120: hot dip zinc alloy plating layer

Claims (8)

delete Hot-dip zinc alloy plating layer is formed on the surface of the base steel sheet 3 ~ 25㎛ thick,
The hot-dip zinc alloy plating layer by weight, magnesium (Mg): 0.5 ~ 2.0%, aluminum (Al): 1.0 ~ 3.0%, misch metal (misch metal): 0.02 ~ 0.5% and the remaining zinc (Zn), A hot-dip zinc alloy plated steel sheet having a surface roughness Ra of 1.0 µm or less and showing glossiness of 200 or more at an incident angle of 60 °.
3. The method of claim 2,
The hot dip zinc alloy plating layer
Silicon (Si): Hot-dip zinc alloy plated steel sheet, characterized in that it further comprises 0.02 ~ 1.0% by weight.
(a) preparing a molten zinc alloy plating solution composed of magnesium (Mg): 0.5 to 2.0%, aluminum (Al): 1.0 to 3.0%, misc metal: 0.02 to 0.5% and the remaining zinc (Zn) in weight% ; And
(b) continuously immersing a base steel sheet in the molten zinc alloy plating solution to form a plating layer having a surface roughness Ra of 1.0 µm or less and a glossiness of 200 or more for an incident angle of 60 ° on the surface of the base steel sheet; Hot-dip zinc alloy plated steel sheet manufacturing method comprising a.
5. The method of claim 4,
The molten zinc alloy plating solution
Silicon (Si): hot dip zinc alloy plated steel sheet manufacturing method characterized in that it further comprises 0.02 ~ 1.0% by weight.
5. The method of claim 4,
In the step (b)
Hot-dip zinc alloy plated steel sheet manufacturing method characterized in that the temperature of the hot-dip zinc alloy plating solution is maintained at 430 ~ 480 ℃.
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