JPH051353A - Galvanized steel sheet excellent in adhesion - Google Patents

Abstract

PURPOSE:To manufacture a galvanized steel sheet excellent in adhesion of plating by arranging a steel having a specified compsn. constituted of high C, low Si and low Mn on the surface and back faces of a steel having a specified compsn. constituted of low C, high Si and high Mn. CONSTITUTION:A steel contg. <=0.01% C, 0.05 to 3.0% Si, 0.1 to 4.0% Mn, <=0.2% P, <=0.025% S, 0.010 to 0.1% sol Al, <=70ppm N and one or >=two kinds among <=0.1% Nb,<=0.1% Ti and <=50ppm B and the balance Fe with impurities is used as an internal layer. A steel contg. 0.01 to 0.2% C, <0.05% Si, <l.5% Mn, <0.03% P,<=0.025% S, 0.010 to 0.1% sol Al and <=70ppm N and the balance Fe with impurities is arranged on the surface and back faces of the above steel as the internal layer. This steel sheet is galvanized and is subjected to alloying treatment under heating to improve its adhesion of plating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot-dip galvanized steel sheet having excellent plating adhesion.

[0002]

2. Description of the Related Art Conventionally, when a high-strength hot-dip galvanized steel sheet is manufactured, cold-rolled steel sheet is generally produced by adding high Si, high Mn, and high P to the steel during cold-rolled steel sheet production. However, when a large amount of the additive material as described above is contained, particularly when the addition ratio of Si is high, plating cannot be performed at all when the plating adhesion is deteriorated. It may be plating,
Prior to plating, it is also practiced to remove the concentrated Si or the like from the surface portion of the steel sheet in the grinding surface layer portion and then perform plating.
For this reason, it is difficult to surely eliminate the non-plating, and the productivity is lowered. When iron-zinc alloy-plated steel sheet is formed by heat-alloying after plating, iron (steel sheet) cannot be uniformly diffused into the plating layer due to the thickening element in the steel sheet surface layer. It is a companion.

[0003]

Therefore, the present inventors have
As a result of various studies to solve the above problems, the solution is to change the composition of the inner and outer layers of the steel sheet. Its characteristic is that C: 0.
01% or less, Si: 0.05 to 3.0%, Mn: 0.1
~ 4.0%, P: 0.2% or less, S: 0.025% or less, sol.Al: 0.010 to 0.1%, N: 70p
pm or less and Nb: 0.1% or less, Ti: 0.1% or less, B: 50 ppm or less of one or more, and the balance: impurities: and Fe on the front and back surfaces of steel, C: 0.01 to. 0.
2%, Si: less than 0.05%, Mn: less than 1.5%,
P: 0.03% or less, S: 0.025% or less, sol.
Al: 0.010 to 0.1%, N: 70 ppm or less,
Residue: A hot-dip galvanized steel sheet excellent in plating adhesion obtained by hot-dip galvanizing a steel sheet on which a steel made of impurities and Fe is arranged.

[0004]

The present invention will be described in detail below. As described above for the present invention, the high-strength steel sheet as the inner layer, as the outer layer on the front and back surfaces of the inner layer, a high ductility steel sheet with a small amount of additive material is arranged, and a plating original plate with less surface defects and plating, the plating adhesion is improved. It will improve. Further, the component as the inner layer imparts a function as a high-strength steel sheet, so C: 0.01% or less, Si: 0.05 to 3.0.
%, Mn: 0.1 to 4.0%, P: 0.2% or less, so
l.Al: 0.01 to 0.1%, and to impart aging property, Nb: 0.1% or less, Ti: 0.1% or less, B:
One or two or more 50 ppm or less is contained. If the content of C in the above components exceeds 0.01%, the workability may deteriorate, and if the content of Mn exceeds 4.0%, the same difficulties may occur, which is not preferable. When P exceeds 0.2%, there is a risk of deterioration of secondary working brittleness, which is not preferable. The upper limits of Nb, Ti, and B are the above C amount and N amount 70p.
It is pm or less, and is an amount necessary for fixing these (imparting aging).

Next, as a component of the outer steel sheet to be placed on the front and back surfaces of the steel sheet as described above, high ductility steel is used to prevent surface defects during rolling and the like, improve plating adhesion, and heat treatment after plating. For uniform alloying by
Reduce additive elements other than iron. C: 0.01 to 0.2
%, Si: less than 0.05%, Mn: less than 1.5%, P:
0.03% or less, S: 0.025% or less, sol.A
l: 0.010 to 0.1%, N: 70 ppm or less. The outer layer steel sheet as described above prevents the surface flaws of the inner layer from being exposed, improves the plating adhesion, and makes the iron diffusion into the plating layer uniform during the heat alloying treatment. In order to improve the value of Si, the content of Si is less than 0.05%, and the amount of Mn, which easily oxidizes and damages the surface properties of inclusions, is less than 1.5%. The outer layer serves to prevent the surface flaws from being exposed and improve the plating adhesion, as described above, and may be thin or well arranged. As the overall plate thickness, 0.3 to 3.2 mm used as a plated steel plate is sufficient. Next, as a method of manufacturing a plating base plate, for example, a slab is formed by a casting method, a hot press bonding method, an explosive bonding method, etc., and then a cold rolled steel plate (strip) is formed by a normal steel plate manufacturing process, and then a continuous hot dip galvanizing line. The steel sheet is passed through to make hot-dip galvanized steel sheet (band). If necessary, it is introduced into an alloying furnace in the line after plating and subjected to heat alloying treatment to obtain a galvannealed steel sheet.

[0006]

EXAMPLES Next, examples of the present invention will be given together with comparative examples.

[0007]

[Table 1]

[0008]

[Table 2]

Note 1: Examples 1 to 4 are cast by continuous casting,
The slab is hot-rolled (finishing temperature: 780-930 ° C., coiling temperature 500-800 ° C.), pickled, cold-rolled, continuously annealed (770 ° C. × 40 seconds), and temper-rolled. Cold rolled steel sheet. In Examples 5 to 7, hot-pressing was used to form a slab, and then cold-rolled steel sheets were prepared as described above. Note 2: In each of the comparative examples, a cold-rolled steel sheet was obtained by continuously casting the components of the inner layer steel as described above. Note 3: As for the outer layer, the same components as the front and back surfaces of the inner layer were used in each of the examples. Note 4: Hot dip galvanizing was carried out in a continuous hot dip galvanizing line, and the alloying treatment in which the coating weight was controlled to 40 g / m ² was performed by heat treatment in an alloying furnace (plate temperature 500 ° C x 10 seconds) in the line. . Note 5: In the comparative example of the alloying situation, the plated steel sheet (strip) in which the non-plating occurred was alloyed and the alloying situation of the plated part was investigated.

[0010]

As described above, according to the present invention, Si
In high-strength steel and the like due to addition of etc., non-plating can be reliably eliminated, and a great industrial effect can be achieved.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yu Niwa             5-3 Tokai-cho, Tokai-shi, Aichi Nippon Steel Corporation             Ceremony Company Nagoya Steel Works

Claims (2)

[Claims] 1. C: 0.01% or less, Si: 0.05 to
3.0%, Mn: 0.1-4.0%, P: 0.2% or less, S: 0.025% or less, sol.Al: 0.010
~ 0.1%, N: 70 ppm or less and Nb: 0.1% or less, Ti: 0.1% or less, B: 50 ppm or less, one or more kinds, and the balance: front and back surfaces of steel consisting of impurities and Fe In addition, C: 0.01 to 0.2%, Si: less than 0.05%,
Mn: less than 1.5%, P: 0.03% or less, S: 0.0
25% or less, sol.Al: 0.010 to 0.1%,
A hot-dip galvanized steel sheet having excellent plating adhesion, which is obtained by performing hot-dip galvanizing on a steel sheet on which a steel consisting of N: 70 ppm or less and the balance: impurities and Fe is arranged. 2. A hot-dip galvanized steel sheet having excellent plating adhesion according to claim 1, which is heat-alloyed after plating.