JPH0417652A - Hot-dip al-mn alloy coating method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an Al--Mn alloy melt coating method.

(Prior art and its problems) As an alloy hot-dip plating method, for example, Japanese Patent Application Laid-Open No. 64-2
No. 1049 discloses that a steel plate is introduced into an alloy bath containing 1 to 12% iron in a zinc bath and plated. This alloy plating contains iron and has some difficulty in corrosion resistance when used, for example, in construction materials, civil engineering materials, etc., and there is a strong demand for plated steel sheets with excellent corrosion resistance.

(Means for solving problems) The gist of the invention is as follows.

An A I-M n alloy hot-dip plating method, which comprises plating a steel plate by bringing it into contact with a molten alloy plating bath consisting of 0M n:0, 5 to 20%, and the balance A1.

■ Cr, 1'i Sn, SbS P% Mg,
The A I-M n alloy hot-dip plating method as described in (1) above, characterized in that the steel plate is brought into contact with an alloy plating bath containing 0.1 to 5% of one or more types of Ni.

(2) The Al-Mn alloy hot-dip plating method as described in (1) or (2) above, characterized in that the plated steel sheet is cooled from over 600°C to 450°C or less at a cooling rate of 30°C/s or more after plating.

(2) The Al-1 according to any one of (11) to (11) above, characterized in that the steel plate is plated with one of P, Cr, Fe-P, and Fe-B in advance, and then hot-dipped with Al-Mn alloy. M
n-alloy hot-dip plating method.

(Function) The present invention is a method of plating with a molten alloy bath consisting of 0.5 to 20% Mn and the remainder Al. If the Mn content is less than 0.5%, corrosion resistance will be poor, and if it exceeds 20%, the bath temperature must be lowered even more. There is a problem that impurities mainly composed of F phase accumulate, and furthermore, during the cooling process, a large amount of alloy mainly composed of F phase is generated, which deteriorates plating adhesion (workability). With such an Al-Mn alloy bath, fluidity suitable for plating can be ensured at a bath temperature of 700 to 1000°C, and the alloy becomes reliable, allowing industrially stable plating.

By applying such alloy hot-dip plating, the crystal grains of the plating are fine, isotropically and uniformly distributed, with almost no crystal gaps, and are stably generated as intermetallic compounds, resulting in improved corrosion resistance and workability. It becomes an excellent plating layer. moreover,
Since the temperature of the toothpick bath can be raised, plating can be done in a short time and sufficient adhesion can be achieved in 1 to 10 seconds. The plating method may be any method, such as immersing the steel plate in a plating bath, spraying the paint bath in a spray form, or the roll coater meniscus method. Plating is possible and the amount of adhesion is 30-5
00. /2 is enough.

After plating is applied in this manner, the amount of adhesion is controlled by, for example, swiping as necessary, and then the plated metal is air-cooled to solidify at an early stage to form a product.

If the product is manufactured in this way, the latent heat of the plated steel plate will also be high if it is plated on the high temperature side, and the iron (steel plate) after plating will
diffuses to the bottom of the plating layer, and during cooling, the F becomes hard and brittle.
An alloy layer mainly consisting of phase is likely to be formed, which may reduce the adhesion of the plating layer. In order to reliably avoid this, for example, a plated steel plate that has been heated to over 600°C after plating must be heated to 30°C.
It is sufficient to cool down to 450°C or less (the lower limit is room temperature) at a cooling rate of /s or more.

In addition, for example, before applying alloy hot-dip plating, P
, Cr, Fe-P (P: 1-50000pp
m), 1 of Fe-B (B: 1 to 50,000 ppm)
By plating 0.2 to 10g/-2 seeds (electroplating, vapor deposition plating, etc.), this acts as a barrier, preventing diffusion of iron (steel plate) into the plating layer, and reducing F at the interface between the steel plate surface and the plating layer. The formation of an alloy layer mainly composed of phases can be reliably suppressed. This is preferable because rapid cooling becomes unnecessary. Furthermore, when plating a steel plate by immersing it in a 7-ply bath, it is possible to reliably prevent iron (steel plate) from leaching into the plating bath, prevent changes in the plating bath composition, and prevent quality deterioration. Therefore, it can bring about excellent effects. If the adhesion amount is less than 0.211/112, it is difficult to obtain a sufficient effect, and if it exceeds 10 g/m2, the effect will be saturated.
It may be 0.2 to 10 g/m2.

Furthermore, in order to improve the - layer heavy erodibility, the Al-M
Cr, Ni, Ti, Sn, Sb into the n-alloy bath.

It is preferable to add one or more of P and M in an amount of 0.1 to 5%; if it is less than 0.1%, the effect is small, and if it exceeds 5%, the effect of improving corrosion resistance tends to be saturated. This is not preferable because it increases the viscosity of the plating bath, lowers its fluidity, and deteriorates the controllability of a low coating amount and the appearance finish.

By adding such alloying elements in the form of powder, they can be easily melted and an alloy bath can be reliably obtained. In addition, it can be dissolved in granular or plate form by immersing it in high temperature for a long period of time. Industrially, the plating bath concentration can be easily and reliably controlled by creating an ingot of a constant composition from a master alloy.

When applying such plating, for example, a steel plate (including a pre-plated steel plate) is annealed in a normal plating pre-treatment furnace and the surface is cleaned, and then alloy hot-dip plating can be applied as described above. Usually, the annealing temperature is 70
The 6-alloy plating layer is heated to a temperature of 0 to 800°C by, for example, gas, induction, energization, electric arc, plasma arc, or the like. In order to improve heating cost and temperature controllability, two or more of the above heating methods can be combined.

(Example) Examples of the present invention are shown in Table 1 along with comparative examples.

Note 1: Steel plate is Ni, Ti-based ultra-thin low carbon steel (C: 0.02
%, Mn: 0.14%, P: 0,011%, S: 0
．． 005%, Si2 0.013%, Ti:0.011
%, Nb:o, 0.16%, remaining Fe and impurities, thickness 0.71).

Note 2: Pre-plating was performed by electroplating.

Note 3: Annealing was performed at 828%, residual N, and atmosphere.

Note 4 Metal elements are added to the second plating bath in the form of powder with an average size of 300μ.

Note 5: The amount of plating deposited was controlled to 60 H/w2 by swiping the amount of plating on the plated steel sheet that passed through the bath.

Note 6: For cooling, water was atomized to form air water, which was sprayed onto the plated steel plate (otherwise, the plated metal was air-cooled to about 350°C at about 14°C/s).

Note 7 = Corrosion resistance is 70℃ drying for 3 hours → salt water (3% x 50
°C) 2 hours → Leave at room temperature for 2 hours → Salt water spray test (JIS
Based on Z 2371) 1.5 hours → wet (80% humidity, 50°C) 15.4 hours cycle, measure the red rust area (%) after 10 cycles of treatment.

◎: 3% or less ○: More than 3% and less than 5% Δ: More than 5% Note 8 2. Adhesion is determined by bending a plated steel plate into a U-shape and adhering it to the 0.8Iw4 plate, returning it to Heisei, and applying cellophane to the inside of the bent part. Adhesive tape is applied and peeled off to measure the peeling of the plated metal at the bend.

◎: Within 0.51 ○: More than 0.5s+s 1. Within Omw △: 1. OLIIm Super (Effects of the Invention) The present invention can improve the corrosion resistance and workability of steel sheets, and can produce industrially while reliably maintaining high productivity, resulting in extraordinary industrial effects. can get.

Claims (4)

[Claims] (1) An Al-Mn alloy hot-dip plating method, which comprises plating a steel plate by bringing it into contact with a molten alloy plating bath consisting of Mn: 0.5-20% and residual Al. (2) The steel plate is brought into contact with an alloy plating bath containing 0.1 to 5% of one or more of Cr, Ti, Sn, Sb, P, Mg, and Ni. Al
-Mn alloy hot-dip plating method. (3) 30℃/s from over 600℃ after plating plated steel plate
3. The Al--Mn alloy hot-dip plating method according to claim 1, wherein the Al--Mn alloy hot-dip plating method is performed at a cooling rate of 450 DEG C. or less. (4) P, Cr, Fe-P, Fe-B medium 1 on the steel plate in advance
Al according to any one of claims 1 to 3, characterized in that the seed is plated and then Al-Mn alloy hot-dip plating is applied.
-Mn alloy hot-dip plating method.