JPS5834192A - Surface treatment steel plate which is excellent in corrosion resistance and water adherence resistance after painting - Google Patents

Abstract

PURPOSE:To obtain a surface treatment steel plate which is excellent in corrosion resistance and water adherence resistance after painting, by forming a Ze-Fe alloy electroplating layer containing Fe of a specific quantity, on a steel plate, and also forming an iron plating layer on said layer. CONSTITUTION:On a steel plate, a Zn-Fe alloy electroplating layer containing 7-40% Fe is formed as the first layer. Thickness of the plating layer of the first layer is set to >= about 1g/m<2>, and electroplating is executed by a sulfate bath, etc. Subsequently, the second layer is formed by executing iron plating on the first layer. As for the second layer, thickness of >= about 1g/m<2> is required. In this regard, as for this second layer, an iron plating layer containing <=40% Zn is also available.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a surface treated steel sheet K11 which has excellent corrosion resistance and water resistant adhesion after I11 hair.

First, galvanized steel sheets have excellent corrosion resistance, so they are widely used in places exposed to high corrosion conditions.

In recent years, various types of N-lead plated steel sheets have been developed to prevent rust in automobiles. [K has been installed and is now mainly used for the inner plate KI2. In this case, use galvanized steel sheet F!
In addition to bare corrosion resistance, corrosion resistance after painting is 1%, and paint adhesion is 1%.
Adhesion after immersion in hot water has become increasingly important - Electric galvanized medium steel sheets and hot-dip galvanized steel sheets in li dormitories have difficulty in water-resistant adhesion, and even alloyed hot-dip galvanized steel sheets have poor water-resistant adhesion. It has the disadvantage of being inferior. However, although the water resistant adhesion of 1-alloy hot-dip galvanized steel sheet is improved compared to that of non-alloy galvanized steel sheet, cold abrasive steel sheet is slightly inferior.

In addition, because it is manufactured in a continuous fIII metal life line, steel 1 [0] is inferior to electrolytic 1 lead plating in terms of workability, uniformity of plating adhesion, ability to handle thin coatings, etc.

There? , the well-known 7, N-PE alloy electroplating method is called 1-alloy hot-dip galvanizing and approximately #I! l
We manufactured 20-re alloy electroplated steel plates for company cars, but the water resistance adhesion was the same as that of 1-alloy molten zinc, but it was not as good as cold rolling steel.

The present invention solves the various problems of conventional galvanized steel sheets as described above.

The object of the present invention is to provide a surface-treated steel sheet that has excellent corrosion resistance and paint adhesion after painting, especially adhesion after immersion in hot water.

I11 According to the present invention, the surface-treated steel corrugated steel sheet C having excellent corrosion resistance and water-resistant adhesion after mounting may be referred to as the steel sheet according to the present invention. ) is (1) a steel plate containing Zn containing 7 to 40 Fe.
- A surface-treated copper plate with excellent corrosion resistance and water-resistant adhesion, which is characterized by having a first layer of Fe alloy electroplating layer and a second layer of iron plating layer thereon. (2) Zn-F containing 7 to 40 min of Fe in one plate;
A first layer of e-alloy electroplated layer and above K Zn
401 The second invention is a surface-treated steel sheet with excellent post-painting resistance and water-resistant adhesion, characterized by having two layers of Fe plating layers containing: .

Details about one plate related to the present invention mrc! B2WiJsu b.

A ZN-PE alloy electroplating containing 7 to 40 Is of Fa is applied to a steel plate to form a first NI.
The thickness of the plating layer is desirably about 1 g/- or more in order to maintain good durability of the copper plate.

However, the F content of ZFI-Pa alloy, 7 ducks.
If untreated, the resistance will deteriorate by %. If the content exceeds 40%, the liqueurability will not improve much and will be saturated.
The Fe content is 7 to 40. This zn-F alloy electroplating can be performed by a conventional method from, for example, a sulfate bath or a chloride bath.

On top of this first layer of Zn-7F alloy plating layer containing 7 to 40% Fe, iron plating is applied to form the second layer. The phosphate treatment carried out resulted in approximately 1 g of flaking of the surface layer. Taking into consideration the fact that the plating thickness decreases due to pressing with the mold during press work, etc., it is necessary to set the amount to about 1 g/- or more. Electroless metal plating or thickening may be considered as a plating method for this iron plating, but electroplating is effective from the viewpoint of durability.

In the iron plating of the 2nd layer: If Z1140 or less is contained, the IkII adhesion will be as hot as when only Fs is used. In this case, the corrosion potential of the 2nd layer will shift to a more base direction. However, since the potential difference in the first layer is reduced, the loincloth aging resistance becomes more advantageous than when only iron plating is used. And the Zn content is 4
If it exceeds 0%, this effect will decrease. In addition, Ni is included in the iron plating of the second layer of teeth.

When containing a trace amount (20% or less) of Cot MO, Zn
-It has an effect on the water-resistant adhesion of Ni alloy plating.

Examples of the copper plate according to the present invention will be described together with comparative examples.

EXAMPLE Four cold-rolled steel sheets were electrolytically degreased and pickled according to a conventional method.The first layer of Zn--Fe alloy electroplating was performed under the conditions described below.

(1) Plating bath 1 iron sulfuric acid (Fe3O3 7 x 0) 300g/A
Zinc sulfate (ZnSOa ・7&O) 120g/A
Aimo senrimu sulfate (, (NH4) Mayuzumi 5O4)
PH of 30g/4 bath: 2.0 Bath temperature: 60°C Electrical RII variation: 30A/dm After washing with water, the steel plate coated with one-layer OZr*-Pa alloy electroplating was subjected to the second layer electroplating under the following conditions. Iron plating was done.

(2) Plating bath ferrous sulfate (Fe80a ・7HsO) 500
g/LiIII! Ammonium ((NH4) Yuki 804)
30g/j bath OPH: 2.0 Bath temperature: 60℃ R density: 50h/dd Including Zn in the second layer of iron plating, the above plating bath K11II! Zinc (znSO4・7Hs
O) It is better to use a bath containing 15g/14,
In case of kernels, Zn content is 26 capsules.

The copper plate according to the present invention obtained by the above-described method and the electric galvanized medium pot 11i% alloyed molten summer lead medium steel sinter as a comparative example were each tested based on the specifications of the automotive m-loading type. The process of acid treatment (dip method), cationic electrodeposition painting, intermediate coating, wet sanding, and top coating] makes it possible to achieve the desired results! Then, tests were conducted on water resistant adhesion and corrosion resistance after electrodeposition.

The result is number 115! Shown below.

Table 1 1) The test piece after the top coating was immersed in 40° C. hot water for 240 hours and then subjected to a 2wm goblin test, and evaluated by the number of goblets that peeled out of 100 goblets.

◎: 0 pieces - ○: 1 to 10 pieces, Δ: 11 to 20 pieces tx: 21 pieces or more.

2) A cross cut was made on the test piece after electrodeposition coating! & Hanasui g test (JIS Z 2371) fr6001
11 MI was conducted and evaluation was made based on the width of the bulge from the cross cut of the coating film.

◎: 1- or less, ○: 1~2■, Δ: 2~5+wnX
:3- That's all.

As is clear from this table, the steel plate according to the present invention is
Regardless of the water resistance adhesion and the corrosion resistance after painting,
Conventionally used electrogalvanized steel sheet, or
It has much superior properties compared to alloyed hot-dip galvanized steel sheets.

As explained above, since the present invention has the above-described configuration, it is a press-fit surface-treated steel sheet that has excellent post-painting resistance and water-resistant adhesion.

471

Claims (2)

[Claims] (1) 7,n- containing fe7-404I in steel plate
The resistance after Ik mounting is characterized by having a first layer of PE alloy electroplating layer and a second layer of iron metal layer thereon.
Surface-treated steel sheet with excellent water resistance and adhesion. (2) Zn-1i containing Fe7-401 in steel plate
"e-alloy electroplated layer first layer, and KZn4D on top
- A surface-treated steel sheet with excellent corrosion resistance and water-resistant adhesion after I11 loading, characterized by having a second layer of Femets dP layer containing: