JPH02198832A - Rustproof processed thick steel plate and preparation thereof - 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 [Field of Industrial Application] The present invention relates to a rust prevention treatment suitable for thick steel plates, particularly thick steel plates with a thickness of 4.5 to 200 am. This invention relates to a thick steel plate that has been subjected to anti-corrosion treatment using a mechanical plating method in combination with zinc coating and primer coating.

[Conventional technology]

BACKGROUND ART Conventionally, it has been known to provide a zinc coating to the surface of a steel material as one of the typical rust prevention treatments for steel materials.

Commonly used zinc coating methods include hot-dip galvanizing and electrogalvanizing. Although this type of zinc coating is suitable for thin steel sheets and wire rods, it is suitable for hot-dip galvanizing baths, electroplating bathtubs, etc. It is not economical for processing thick steel plates due to the equipment.

Therefore, in recent years, as an alternative to zinc coating methods such as hot-dip galvanizing method and electrolytic galvanizing method, for example,
Zinc coating by a mechanical plating method as disclosed in No. 9312 and Japanese Unexamined Patent Publication No. 81-38870 is attracting attention. In zinc coating using the mechanical plating method, a blasting material consisting of iron powder or iron alloy powder as a core and zinc or zinc alloy coating on the outside is sprayed onto the steel surface using an ordinary shot blasting device. The zinc coating on the powder surface is transferred to the steel surface, resulting in a zinc coating layer with excellent adhesion.

By applying zinc coating using such a mechanical plating method, it is possible to economically apply zinc coating to thick steel plates having a thickness of 4.5 mm or more without causing thermal distortion.

[Problem to be solved by the invention]

Now, when a thick steel plate that has been subjected to rust prevention treatment is used as a steel relic material for ships, bridges, buildings, etc., the rust prevention treatment is guaranteed for at least six months after the steel plate is shipped from the factory under extremely harsh conditions. 0 For example, assuming that thick steel plates are used for bridges over straits, etc., the rust prevention treatment will be 60% when exposed outdoors in the presence of sea salt particles.
In other words, the rust prevention treatment shall be maintained for at least 6 months, which is the time required for the steel plates to be assembled by bolting, welding, etc. as a component of the structure. It is said that Note that after the thick steel plate is assembled as an element of a structure, another anti-corrosion treatment is applied to the entire structure.

Therefore, the object of the present invention is to prevent red rust from forming on thick steel plates, especially thick steel plates with a thickness of 4.5 mm or more and 200 I or less, for a long period of 6 months or more even under harsh conditions in the presence of salt water, etc. The object of the present invention is to provide a rust prevention treatment method that can be easily and economically applied to such thick steel plates, and a thick steel plate subjected to the rust prevention treatment.

[Means to solve the problem]

The rust-prevention treated thick steel plate according to the present invention includes a thick steel plate material, a zinc coating layer of 10g7m2 to 50g/m" formed on the surface of the thick steel plate material by a mechanical plating method, and a ~15μ- resin-based zinc primer coating.

In addition, according to the rust prevention treatment method of the present invention, 10g7
A zinc coating layer of m2~50g/+*2 is formed, and a resin-based zinc primer is applied on this zinc coating layer.
A resin-based paint layer of 5μ thick is formed.

[For production]

According to the present invention as described above, it is possible to coat a thick steel plate with zinc without causing thermal distortion, and the formation of a zinc coating layer on a thick steel plate can be easily performed by using a shot blasting device or the like. The application of the primer paint on the zinc coating layer is also easily carried out using a spray device or the like. In addition, in the rust prevention treatment method according to the present invention, by combining the rust prevention treatment with a zinc coating layer and the rust prevention treatment with the application of a resin-based zinc paint, the steel plate can last for 6 months even under harsh conditions such as the presence of salt water. It can exhibit red rust resistance over a long period of time.

〔Example〕

The present inventor has found that when a thick steel plate is coated with zinc using a mechanical plating method, when only a resin-based zinc primer is applied, and after a zinc coat is applied to a thick steel plate using a mechanical plating method, a resin-based zinc primer is applied. Tests were conducted to determine how long the anti-rust treatment could be maintained during outdoor exposure and in the presence of salt water. The test results are shown in Table 1.

The test conditions are as follows.

(1) Outdoor exposure period: 9 months from December 28, 1988 to September 30, 1988 (2) Test piece: A 5 x 100 x 150 thick steel plate piece (SS41) was descaled by shot blasting. After that, several sheets were coated with zinc by mechanical plating method at 10 g/m" and 24 g/m2, respectively, and were coated with resin-based zinc primer (Z/P).
After applying a zinc coating of 10 g/m by mechanical plating to multiple sheets of 5.3μ ring, 9.7μ ring, and 16.1μ ring, resin-based zinc primer (Z/P) was applied. A plurality of sheets were prepared, one coated with only 5.3 μm layer and one coated with only 9.7 μm layer.

(3) Test details: Two test pieces with each surface treatment were prepared, one of which was left outdoors, and the other was sprayed with salt water once a week.

(4) Evaluation method: As is clear from Table 1, the red rust occurrence area rate, when only zinc coating was performed by mechanical plating, it was left outdoors (atmospheric exposure).
ff), thick zinc coating has a rust-preventing effect, but after 6 months, red rust occurred even on the test piece coated with 24g/m'' of zinc.When salt water was sprayed, almost all test specimens were coated with zinc. Red rust was observed over the entire surface of the piece.

In addition, with regard to rust prevention treatment using only zinc-based primer (Z/P'), when left outdoors (exposed to the atmosphere), almost no red rust is observed except for coatings with a thickness of 5.3 μ-; In the case of spraying, red rust with an area ratio of 10% did not occur even on a test piece with a coating thickness of 16.1μ after 9 months had passed.

As is clear from the above description, it has been found that the rust prevention treatment using only zinc coating using the mechanical plating method cannot completely rust prevent a thick steel plate for a long period of more than 6 months. In addition, in the case of rust prevention treatment using a resin-based zinc primer, it is necessary to ensure a coating thickness of at least 16.1μ or thicker steel plates under harsh conditions such as the presence of salt water.
f! : It has become clear that it cannot be completely rust-proofed over a long period of time.

On the other hand, in the case of rust prevention treatment in which a resin-based zinc primer is applied after zinc coating is performed by mechanical plating, the coating thickness of the resin-based zinc primer is 5.5 mm.
Even at 3μ-, no red rust was observed when left outdoors (exposed to the atmosphere) or when salt water was sprayed.

Next, with reference to FIG. 1, an embodiment of the rust prevention treatment method according to the present invention will be described. Referring to FIG. 1, an outline of a rust prevention treatment line for carrying out the rust prevention treatment method according to the present invention is shown, and this rust prevention treatment line is disposed downstream of a thick steel plate rolling line. It is now possible to immediately apply rust prevention treatment to the thick steel plate material obtained from the line.

The anti-corrosion treatment line is the final rolling stage of the thick steel plate rolling line.
A descaling station 12, a zinc coating forming station 14, a first preheating station 16, a first primer application station 18, a second preheating station 20, and a first preheating station 16 are arranged downstream in order from the o side. It consists of two primer application stations 22.

The descaling station 12 is provided with, for example, a shot blasting device, and this shot blasting device performs surface treatment, ie, scale removal, on the rolled thick steel plate material.

After removing the black scale, the steel plate material is sent to the zinc coating forming station 1.
4, and here, while conveying the thick steel plate material,
A zinc coating is applied to both surfaces of the thick steel plate material using a mechanical plating method. At the zinc coating forming station 14, as mentioned earlier, a blasting material consisting of iron or iron alloy as a core and zinc or zinc alloy coated on the outside through an iron-zinc alloy layer is processed using ordinary shot blasting equipment. is projected onto both surfaces of the steel plate material, thereby providing a zinc coating layer on the surface of the steel plate material. The surface roughness of the zinc coating layer thus obtained was 10
Although the zinc coating layer has a rough surface of about 100 .mu.m to 100 .mu.m, the apparent surface area of the zinc coating layer is at least Log/si' or higher. Also, from the economical point of view of forming the zinc coating layer, the upper limit of the coating layer is considered to be 50 g/si''.
A zinc-coated rII layer of 0 to 20 g/m2 is preferred.

The steel plate material provided with the zinc coating layer is then sent to a first preheating station 16 and a first primer application station 18. The first preheating station 16 is configured, for example, as a suitable oven or furnace, in which the steel sheet stock is preheated to a predetermined temperature. The first primer application station 18 is equipped with, for example, a spray device, which applies a resin-based zinc primer (Z/P) onto the zinc coating layer on one surface of the thick steel plate material, and The thickness of the paint layer is preferably within the range of 5 μm to 15 μm.

Considering the deviation in coating thickness when painting thick steel plates, sufficient rust prevention effect can be obtained with less than 5μ theory, and 1
If it exceeds 5μ, it is thought that the resin-based zinc primer alone has an anti-corrosion effect, and there is little need for a zinc coating layer.Since the thick steel plate material has been preheated at the first preheating station 16, it can be applied there. The resin-based paint is immediately dried.

Note that instead of providing the first preheating station 16,
A heating station may be provided downstream of the first primer application station 18 to heat and dry the resin-based paint after application, and if desired, the first preheating station 16 and the heating station may be omitted. The resin-based paint layer may be naturally dried.

On the other hand, when painting the back side, after reversing the thick steel plate material, the second preheating station 20 and the second
A resin-based zinc primer is applied at a primer application station 22.

Both surfaces of the thick steel plate, which has been subjected to anti-corrosion treatment in this way, are coated with 10g/+
A zinc coating layer ranging from m2 to 50 g/st" is formed,
Further, a resin-based zinc paint layer having a thickness of 5 to 15 μm is formed on the zinc coating layer.

〔Effect of the invention〕

As is clear from Table 1, in the rust prevention treatment technology according to the present invention, since the rust prevention treatment by zinc coating and the rust prevention effect by applying a resin-based zinc primer are used together, harsh conditions such as the presence of salt water, etc. The rust prevention treatment of the thick steel plate will be maintained for a long period of at least 9 months, at least 6 months.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing a rust prevention treatment line for performing rust prevention treatment according to the present invention. 12... Descaling station, 14... Zinc coating forming station, 16... First
preheating station, 18... first primer application station, 20...
...Second preheating station, 22...Second primer application station.

Claims (1)

[Claims] (1) Thick steel plate material and 10g/m^2 ~ formed on the surface of this thick steel plate material by mechanical plating method.
A rust-prevention treated thick steel plate comprising a zinc coating layer of 50 g/m^2 and a resin-based zinc primer coating of 5 to 15 μm coated on the zinc coating layer. (2) 1 by mechanical plating method on the surface of thick steel plate material
Forming a zinc coating layer of 0g/m^2 to 50g/m^2,
A method for producing a rust-proof thick steel plate, which comprises forming a primer coating film with a thickness of 5 to 15 μm on the zinc coating layer.