JPS6046359A - Surface treatment of stainless steel plate - Google Patents

Abstract

PURPOSE:To simultaneously perform the plating and annealing of a stainless steel plate, by immersing the cold rolled stainless steel plate in molten copper in a non-oxidative atmosphere. CONSTITUTION:A cold rolled stainless steel plate is immersed in molten copper or copper alloy in a non-oxidative or reductive atmosphere. In this case, the temp. of the molten plating bath is set to a somewhat higher temp. as compared with the m.p. of copper or the copper alloy to be used. By this method, the plating and annealing of the stainless steel can be simultaneously performed and, because no oxide scale is formed on the surface of the steel plate, a plating layer good in the adhesiveness of plating and having a smooth glossy surface is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface treatment method for a stainless steel sheet, and more particularly, to a surface treatment method for simultaneously performing heat treatment and hot-dip metal plating on a stainless steel sheet that has been rolled into a stainless steel sheet.

Recently, copper-plated stainless steel sheets have been developed and are used as decorative materials, utensil materials, interior and exterior materials. The purpose of copper plating on stainless steel sheets is to increase the design of the surface appearance of the stainless steel sheet, and to increase added value by taking advantage of the excellent strength, corrosion resistance, and weather resistance inherent to stainless steel. This is to demonstrate its characteristics as a composite material.

Conventional copper plating: Fi is a so-called electroplating method in which electrochemical plating is performed. In this plating method, since an acidic or alkaline solution such as a sulfuric acid steel bath, a sulfated steel bath, a cyanide copper bath, a birophosphate copper bath, etc. is used as a plating bath, there is a problem of pollution in waste liquid treatment.

Also, the plating g, the bottle is ``the product of breaking wave density and time (quantity of electricity)
Therefore, constructing an electroplating facility with a high production volume requires a long tank and large-capacity pox equipment, which requires a huge amount of equipment service costs, and furthermore, the plating quality becomes unstable. Copper plating of stainless steel also has problems such as requiring a great deal of effort to manage the bath and electrodes.

- In the manufacturing process of electroplating, the base metal stainless steel plate is usually subjected to an annealing process after cold rolling, and then electroplating is applied to the surface, and in some cases, rolling -aA7
t Stainless steel sheets are sometimes electroplated and then annealed, but conventionally both methods involve two processes: main drying and electroplating, and annealing and plating are performed simultaneously in one manufacturing process. □; The purpose of the invention is to eliminate the drawbacks of conventional electroplating and to provide a method for surface treatment of stainless steel plate that can perform plating and annealing at the same time.

The gist of non-invention is as follows.

That is, cold rolling involves tt7' (a step of immersing a stainless steel sheet in molten copper or copper alloy in a non-oxidizing atmosphere or a reducing atmosphere).

The method of surface treatment for stainless steel sheets requires that the steel sheet be annealed at the same time as it is plated or copper alloy plated.

The present inventors focused on the annealing temperatures of various stainless steels and the melting points of copper and copper alloys. That is, the annealing temperatures for softening, recrystallization, and re-solution solidification of the rL stainless steel during rolling are as shown in Table 1 <f! The annealing temperature is slightly different depending on the type, and the annealing temperature is higher in the order of austenitic, ferritic, and martensitic, but all of them have a high annealing temperature of 750
It is within the range of ~1150°C.

Table 1: 10,000, copper alloy The melting point of copper alloy is 1083 when copper alone
℃, but in the case of copper alloys, copper-tin alloys are shown in Figure 1, copper-tin alloys are
As shown in Figure 2 for the zinc alloy and the relationship between the alloy composition and the 76 melting point for the steel/aluminum alloy as the third factor, both have lower melting points than when only the metal is used.

Therefore, by appropriately selecting the composition of Fi copper or copper alloy, the present inventors determined that copper or It has been discovered that by immersing a rolled stainless steel sheet in a molten copper alloy bath, it can be completely annealed and hot-dip plated. The present invention is based on this knowledge.The temperature of the actual hot-dip plating bath is 4L (ki). It is necessary to do so.

Next, in the present invention, the immersion step is limited to a non-oxidizing atmosphere or a reducing atmosphere for the following reason. Rolled tight stainless steel plate at 750℃ in an oxidizing atmosphere
If heated above the above level, Vc scale will be generated on the surface, and even if immersed in a hot-dip plating bath, wettability will be poor and plating will be impossible. Further, in oxidizing atmosphere 2, the surface of the hot-dip plating bath is oxidized, and a shiny plating layer cannot be obtained. However, in a non-oxidizing or reducing atmosphere, no oxide scale is generated on the surface of the stainless steel sheet even if it is heated, so the plating activation is good and a smooth and glossy plating layer can be obtained. Out.

In the present invention, instead of immersing cold-rolled stainless steel in a molten bath of @ or copper alloy having a melting point compatible with the annealing temperature of stainless steel, the two processes can be carried out in one step in a short time. Kotokade@之.

Example 1.

Austenitic stainless steel m5Us304 was cold rolled into a plate yl-1,0m, and the cold rolled plate was immersed in a copper hot-dip plating bath at 1120°C for 60 seconds in a reducing atmosphere of AX gas, and then rapidly cooled in the same reducing atmosphere. As a result, a plating layer with a plating film thickness of 10 to 50 μm and a good appearance is formed, and at the same time, the strain during cold rolling is removed, the stainless steel plate is softened, recrystallized, and re-solid solutionized. Tried.

Example 2 Ferritic stainless steel faS US 444t
/'t The plate thickness was reduced to 0.8 by IHI rolling, and the cold rolled plate was reduced to 9A80%-A820% in a reducing atmosphere using AX gas.
After immersing the brass in hot-dip plating bath 11C at 1050°C for 30 seconds, it was rapidly cooled in the same reducing atmosphere. False brass plated stainless steel plate plating film thickness 10
As is clear from the above examples, this invention was developed during cold rolling at the same time that a shiny brass plating layer of ~50μ was formed. By immersing the cold-rolled steel sheet in molten copper or copper alloy in a molten atmosphere, it is possible to perform annealing and plating of the cold-rolled steel sheet at the same time. I was able to achieve this effect.

(b) Annealing of the rolled NFL-stainless steel sheet is carried out at the same time as the surface treatment, and the annealing time is significantly shortened compared to the conventional continuous annealing furnace, so the number of man-hours is reduced and It is possible to significantly reduce manufacturing costs and improve product yield.

1 bite) The plating layer is l! J1. Because it adheres tightly, uniformly, and firmly, and has few defects such as pinholes, the plating film will not peel off at all even if residual processing is performed on the plated stainless steel plate.

(c) The thickness of the plating film can be easily adjusted by changing the temperature of the hot-dip plating bath, wiping, etc., so even if the plating film thickness increases, there is no need to increase equipment costs and the cost can be reduced. ”
Therefore, since products with various plating thicknesses can be easily manufactured, the range of use thereof is extremely wide, from products in the field of clad steel plates, such as kitchen appliances, equipment for the chemical industry, and components to conventional plated parts.

2) There is no need to treat waste liquid from the plating bath, so there is no problem with pollution.

[Brief explanation of drawings]

The attached pages are binary phase diagrams showing the relationship between the formulation, gold composition, and melting point, and the 7! The ji types are as follows. Figure 1: Copper-tin alloy Figure 2: Copper-zinc alloy Figure 3: Steel-aluminum alloy Representative: Takeo Nakaji, Patent Attorney 1 Figure - C-S,'/, Le No. Figure 2 u Iu 20 50 40 Ko@(170mOSo
100 Figure 3 Cm (, 41% L Procedural Amendment (Method) December q, 1980 Director General of the Patent Office Kazuo Wakasugi L, T:,,:). 1. Indication of the case 1982 Patent Application No. 152672 Chome 1-28 Name (125) Kawasaki Steel Corporation Representative Yagi Sekiho 4, Agent 187 7, Column for brief explanation of the drawings of the specification subject to amendment & Page 8 of the statement of contents of the amendment In lines 8 to 13, ``All attached drawings...3 diagrams of both cylinders...-Copper, aluminum, two metals'' were deleted, and ``Figure 1 shows the alloy composition of copper-tin alloy. Figure 2 is a phase diagram showing the relationship between the alloy composition of steel-zinc alloy and the melting point. Figure 3 is the alloy composition of copper-aluminum alloy and the S melting point. It is a state diagram showing the relationship between j
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Claims (1)

[Claims] (1) A process of immersing a cold-rolled stainless steel plate in molten copper or copper alloy in a non-oxidizing atmosphere or a reducing atmosphere, and applying copper or copper alloy plating to the stainless steel plate. A method for surface treatment of a stainless steel plate, characterized by simultaneously annealing the steel plate.