JPS63250490A - Production of zn-based alloy plated steel sheet - Google Patents

Abstract

PURPOSE:To improve the adhesion of plating with the simple improvement of equipment by grinding the surface of a steel sheet, then electrolytically degreasing and pickling the sheet, and plating the steel sheet surface while still wet. CONSTITUTION:The surface of a strip steel sheet 1 is ground by a grinder 2, the sheet is then passed through an electrolytic degreasing tank 3, a primary water washing tank 4, a pickling tank 5, and a secondary water washing tank 6, and then the sheet is introduced into a plating tank 7 and plated while still wet. When the base material of the steel sheet is ground, the surface roughness of the base material is increased, hence the true surface area is increased and the apparent adhesion is increased, many dislocations are introduced in the vicinity of the base material surface, and the residual tensile stress is through to be released by the dislocations. Those effects due to grinding are eliminated, because the surface is covered with an oxide when the base material is dried after the pretreatment. Accordingly, the sheet is plated while its surface is still wet. By this method, the effect of the grinding can be fully exhibited, and the epitaxy of the plated film is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a Zn-based alloy plated steel sheet with excellent adhesion such as Zn-Ni or Zn-Fe.

[Conventional technology]

Zn-Ni or Zn-Fe alloy plated steel sheets have a Ni content of 10 to 16% by weight and a Fe content of 1% by weight, respectively.
At 0 to 30% by weight, they become single-phase γ phase and r phase, respectively, and exhibit high corrosion resistance, so they have recently been used as a type of surface-treated steel sheet for rust prevention for automobiles. In particular, in recent years there has been a tendency to use it on the outside of car bodies, but the problem with this is low-temperature chipping and peeling. This peeling is -40
This is a phenomenon in which a pebble hits the car body while it is running at temperatures as low as ℃, and the plating layer peels off due to the impact, exposing the steel plate base.
As a result, a significant decrease in corrosion resistance occurs.

Conventionally, as a method to prevent such low-temperature chipping and peeling, in the case of Zn-Ni plating, nickel plating is applied in advance before Zn-Ni alloy plating (Japanese Patent Application No. 61-70).
379), ■ After Nf thin electroplating, Zn-N
Non-current immersion plating of i-alloy (Patent Application 1986-5151)
Methods such as No. 8) have been proposed.

[Problem that the invention seeks to solve]

However, the conventional method described above not only does not necessarily achieve sufficient adhesion improvement efficiency, but also significantly changes the composition and structure of the plating film, and in the case of Zn-Fe alloy plating, , conventional methods are not very effective.

Therefore, the main purpose of the present invention is to simply improve equipment.
It is an object of the present invention to provide a method for manufacturing a Zn-based alloy plated steel sheet that exhibits excellent adhesion.

[Means for solving problems]

The present invention to solve the above-mentioned problems is characterized in that, when producing a Zn-based alloy plated steel sheet, after grinding the surface of the steel sheet, electrolytic degreasing, and pickling, plating is performed while the surface of the steel sheet is kept wet. It is.

[For production]

According to the present invention, when a steel plate base material is ground, the surface roughness of the base material increases and the true surface area increases, so that the apparent adhesion is improved, and a large number of dislocations are introduced near the surface of the base material due to grinding. It is thought that these dislocations relieve the tensile residual stress in the plated film.

However, if the substrate is dried after grinding and after electrolytic degreasing and pickling as a pre-treatment for plating, the surface will be covered with oxides and the effect of the above-mentioned grinding process will be completely lost. According to the invention, after pre-treatment, if the surface of the steel plate is plated in a wet state in the presence of, for example, 0.1 to 100 g/I of water, the effect of grinding will be fully expressed and evixaxial growth of the plating film can be achieved. .

[Specific structure of the invention]

The present invention will be explained in more detail below.

FIG. 1 shows a typical example of the method of the present invention. After the surface of a strip steel plate 1 is ground by a grinding device 2, an electrolytic degreasing tank 3, a primary washing tank 4, a pickling tank 5, and a secondary washing are performed. After passing through tank 6, it is guided to plating tank 7 while maintaining a wet state for plating.

The grinding device 2 is disposed facing both surfaces of the steel plate 1, and is configured to move in the front-rear direction parallel to the steel plate 1 while pressing the grinding member 2a against the surface.

Instead of such a grinding device 2, a grinding roll 21 coated with an abrasive material may be used as shown in FIG. 2, a metal brush 22 may be used as shown in FIG. 3, or a known grinding means may be used. may be used, or a combination thereof may be used.

In any case, as mentioned above, the effect of grinding disappears when the surface dries and oxides are formed, so for example, as shown in FIG.
Between the secondary washing tank 6 and the secondary washing tank 6 and the plating tank 7
Wetting water spray devices 8A and 8B are provided between the two surfaces of the steel plate 1 to spray water onto both surfaces of the steel plate 1 and guide the steel plate 1 into the plating bath 7 in a wet state.

〔Example〕

Next, the effects of the present invention will be explained using examples.

Each of the grinding methods shown in FIGS. 1 to 3 is A.
, B, and C methods, with no further grinding and wet processing (
For those with only electrolytic degreasing and pickling, and those without wet treatment, Zn-Ni and Zn-
After performing Fe alloy plating and applying 20% tensile deformation to a total of 20 plate-shaped tensile test pieces with a parallel length of 50 fl and a width of 2011 mm, the peeled area ratio of the plating film was quantified using an image analysis device. did.

Here, electrolytic degreasing was performed by applying electricity for 20 seconds at a current density of 5 A/drrl in a 10% by weight aqueous solution of NaO11, and the pickling conditions were as follows: By soaking for 1 minute.

The plating conditions are shown in Table 1, and the peeling area ratio is shown in Figures 4 and 5.
As shown in the figure.

1st table ne α, b, c 烃1, spirits 1, 2. ': 3chota ε [daigo'
Rene completed.

As shown in FIGS. 4 and 5, it can be seen that the plated steel sheet according to the present invention has excellent adhesion.

〔Effect of the invention〕

As described above, according to the present invention, a plated steel sheet with excellent adhesion can be obtained.

[Brief explanation of drawings]

FIGS. 1 to 3 are schematic diagrams of examples of the method of the present invention, and FIGS. 4 and 5 are graphs showing peeling test results of the plating film in the examples. 1... Steel plate, 2.21.22... Grinding means, 3...
・Electrolytic degreasing tank, 5... Pickling tank, 7... Plating tank, 8
A, 8B... Water spray device for wetting. Fig. 4 Fig. 5 Sample No. Sample No. 0

Claims (1)

[Claims] (1) A method for manufacturing a Zn-based alloy-plated steel sheet, which is characterized in that, in manufacturing the Zn-based alloy-plated steel sheet, the surface of the steel sheet is ground, electrolytically degreased, and pickled, and then plated while the surface of the steel sheet is kept wet.