JPH03221273A - Production of aluminum laminated steel sheet - Google Patents

Abstract

PURPOSE:To obtain the aluminum laminated steel sheet having an excellent adhesive property, workability and working adhesive property by coating a steel sheet with a specific film, heat treating the steel in a neutral or reducing atmosphere, then laminating and press welding aluminum or aluminum alloy foil of a limited thickness and heat treating the steel sheet under specific temp. conditions. CONSTITUTION:The steel sheet is coated with chromium, chromium alloy, chromium oxide or chromium hydroxide at 0.01 to 0.5g/m<2> in terms of chromium and is heat treated for 1 to 600 seconds at 200 to 800 deg.C in the neutral or reducing atmosphere. The aluminum or aluminum alloy foil having 5 to 200mum thickness is then laminated and after the entire part is press welded at 1 to 15% draft, the steel sheet is subjected to the heat treatment for 1 to 600 seconds at the temp. below the m. p. of the coated aluminum or aluminum alloy from 400 deg.C. The aluminum laminated steel sheet having the excellent adhesive property, workability and working adhesive property is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing an aluminum laminated steel plate by roll pressing and heating.

[Prior Art] Aluminum has excellent properties such as being lightweight, showing good workability, and high corrosion resistance, and can improve its mechanical properties by containing other metals. In terms of mechanical strength, it is inferior to other materials such as iron. In order to give this aluminum the characteristics of iron, the development of a cladding material of aluminum plate and steel plate is underway.

The rolling method, diffusion bonding method, and brazing method are known methods for joining aluminum plates and steel plates, but continuous production is difficult with the brazing method. The diffusion bonding method induces diffusion bonding by applying heat under a pressurized state below plastic deformation, but generally requires a vacuum atmosphere. The rolling methods most suitable for continuous production include cold rolling and hot rolling. Joining by cold rolling generally requires a rolling reduction of several tens of percent, and it is difficult to find appropriate rolling conditions. Further, at a rolling rate lower than this, sufficient bonding cannot be obtained and it is necessary to further perform heat treatment after rolling. However, during hot rolling or heat treatment after cold rolling, a fragile alloy layer grows at the joint interface, reducing workability.

In order to solve these drawbacks, we have developed a method that uses ion etching with a non-oxidizing, low-pressure gas such as argon to remove oxides before rolling, which requires no heat diffusion treatment at a low rolling rate, and a method that eliminates the need for heat diffusion treatment at the bonding interface. There is a method of rolling by inserting insert materials such as nickel or copper to suppress the brittle alloy that forms during heat treatment. In addition, a method of joining the steel plate and aluminum foil by interposing copper at the interface and applying pressure and heat treatment below plastic deformation (Japanese Patent Application No. 1983-
No. 269545). Furthermore, there is a method (Japanese Patent Application No. 1-264856) in which the joint interface is plated with nickel or copper and then rolled to suppress the formation of a brittle alloy.

[Problem to be solved by the invention] When laminating aluminum and steel, which have significantly different amounts of plastic deformation, the conventional cold rolling method generally requires a rolling reduction of 20% or more, which is accompanied by technical difficulties. .

Furthermore, when heat diffusion treatment is performed to improve bonding strength, a brittle alloy grows at the interface, degrading the workability of the laminated steel plate. In addition, in the method of using insert material to suppress alloy formation, a thickness of 10 μm is used when handling the insert material.
It requires more than that and is less economical. In addition, the method of removing oxides from aluminum foil or plate and steel plate by ion etching, which does not require a heating diffusion process, requires vacuum equipment and vacuum technology, and does not require continuity.

There is a problem in terms of economic efficiency.

[Means for Solving the Problems] An object of the present invention is to continuously and economically provide an aluminum laminated steel plate having excellent adhesion and workability through a low rolling reduction.

The gist is chromium, chromium-based alloys, steel sheets coated with chromium oxide or chromium water-retention oxide, or chromium or chromium-based alloys that have been heat-treated in a neutral or reducing atmosphere. , steel plate coated with chromium oxide or chromium water-conserving oxide,
The process involves stacking aluminum or aluminum alloy foils, pressing down and crimping the whole thing, then heat-treating it, and using diffusion bonding to produce an aluminum laminated steel plate with aluminum or aluminum alloy foil coated on one or both sides.

The steel sheet of the present invention is a steel sheet manufactured by a cold rolling method, and includes a low carbon steel sheet, a chromium-added steel sheet, and a nickel diffusion treated steel sheet, and does not matter whether or not it has been softened and annealed. Furthermore, the plate thickness can be selected depending on the application.

On the other hand, the aluminum or aluminum alloy foil is aluminum or aluminum alloy having a thickness of 5 to 200 μm manufactured by a rolling method. Aluminum alloys include alloys containing magnesium, manganese, silicon, and copper. The reason why the thickness is limited is that a foil of less than 5 μm reduces workability and is unsuitable for high-speed production, and a foil of more than 200 μm is uneconomical in terms of material costs.

During manufacturing, the joint surfaces of steel plates are treated with an alkaline solution.
Degrease by immersion treatment or cathodic or anodic electrolysis treatment. Liquid composition and liquid concentration in this case.

Processing conditions such as processing temperature and processing time are not particularly limited. In addition, pickling treatment is performed to remove scale from the surface of the steel plate. The pickling conditions are not particularly limited either, but excessive treatment may cause hydrogen absorption and impede the uniformity of bonding. These degreasing,
If pickling is not performed, the adhesion of the film will be poor (it will be difficult to obtain an aluminum laminated steel plate with sufficient bonding strength).

Next, the joint surfaces of the steel plates are coated with chromium, an alloy containing chromium as a main component, chromium oxide, or chromium water-containing oxide.

The coating method is not particularly limited, but it is economical to use electroplating for chromium and chromium alloys, and to use chemical conversion treatment for chromium oxide and hydrated chromium oxide. At this time, the amount of film of chromium, chromium alloy, chromium oxide, and chromium hydrated oxide is 0.0 as the total amount of chromium.
1 to 0.5 g/m2 is suitable. The reason for limiting the amount of film is that if it is less than 0.01 g/m2, sufficient improvement effect will not be observed, and if it exceeds 0.5 g/m2, the bonding force will be reduced.

When chromium is coated by electroplating, heat treatment of the steel sheet can remove gases or liquids such as hydrogen that have been occluded or adsorbed by the electric treatment, improving the uniformity of the bond. The atmosphere for this desorption process is hydrogen,
Any non-oxidizing atmosphere such as nitrogen or argon may be used.

In this atmosphere, a chromium-coated steel plate was
Heat for 1 to 600 seconds at a board temperature of ~800°C. Desorption treatment is possible at temperatures below 200°C, but the treatment time becomes longer and workability becomes worse. Further, if the heating time is less than 1 second, the effect of the desorption treatment is not observed even at a plate temperature of 800° C., and if the heating time is 600 seconds or more, the effect is saturated. Preferably it is 60 seconds, but 600 seconds may be required to improve mechanical properties.

Next, the treated steel sheet and aluminum or aluminum alloy foil are stacked on top of each other, and the whole is rolled down at a rolling rate of 1 to 15%. The rolling rate varies depending on the steel plate used and the thickness and hardness of the aluminum or aluminum alloy foil. For steel plates that have not been annealed, sufficient bonding strength can be obtained with a rolling reduction of about 1%. Also, 1
If the rolling rate is increased to 5% or more, wrinkles may occur.

Aluminum or aluminum alloy foil can be coated on both sides or one side of a steel plate, but if the foils are laminated symmetrically and rolled down, warping caused by a difference in linear expansion coefficient can be eliminated.

Next, in order to impart good adhesion to the aluminum laminated steel sheets temporarily joined by rolling, heat treatment is performed for 1 to 600 seconds at a temperature of 400° C. below the melting point of the coated aluminum or aluminum alloy foil. If the temperature is lower than 400°C and the temperature is lower than 1 second, the effect of improving adhesion is weak. Although bonding continues even after 600 seconds, the effect is saturated. When performing continuous high-speed production, 60 seconds or less is preferable. Of course, the heat treatment at a certain temperature or higher can also serve as softening annealing.

The atmosphere during heating is not limited and may be hydrogen, nitrogen, argon, or a mixed gas thereof. Alternatively, heating may be performed in air. The pressure applied during heating is not particularly limited.

[Function] A strong oxide film exists on the surface of aluminum or aluminum alloy foil, but by rolling the foil over a steel plate, this oxide film is destroyed at the joint surface and a new surface appears, causing oxidation. There is no need to remove the membrane. The chromium, chromium alloy, chromium oxide, or chromium hydrated oxide that coats the steel sheet not only covers defects on the surface of the steel sheet, but also prevents the growth of brittle iron-aluminum intermetallic compounds during heat treatment, which is promoted by the newly formed surfaces. It is thought that an aluminum laminated steel sheet with excellent processing adhesion can be obtained in order to suppress this. Furthermore, the presence of a chromium layer in the aluminum and iron content suppresses the formation of a carburized layer, making it possible to perform heat treatment under conditions that can improve the machining properties that deteriorated during rolling.

[Example] The present invention will be specifically explained with examples.

Example 1 A 0.30 mm thick steel plate that had been subjected to normal degreasing and pickling treatment was treated with 100 g/I of chromic anhydride! , 5 g/I of sodium fluoride! In a solution containing chromium at a temperature of 50°C, a steel plate is used as a cathode at a current density of 4000 A/m2, and metallic chromium and chromium hydrated oxide are 0.5 g/m2 in terms of chromium content.
It was processed so that The treated steel plate was heat-treated in a hydrogen gas atmosphere for 60 seconds at a plate temperature of 200°C, then layered with 200 μm thick aluminum foil, rolled at a rolling reduction of 5%, and then placed in air. Board temperature 400℃
Heat treatment was performed for 60 seconds under the following conditions to obtain an aluminum laminated steel plate.

Example 2 A 1.0 mm thick steel plate that had been subjected to conventional degreasing and pickling treatment was heated at 60°C in the presence of 80 g/l of chromic anhydride, 0.3 g/l of sulfuric acid, and 0.6 g/l of fluoroboric acid.
The metal chromium and chromium hydrated oxide were treated in a solution using a steel plate as a cathode so that the amount of chromium was 0.01 g/m2. The steel plate subjected to this treatment is heat treated for 1 second at a plate temperature of 800°C in an argon gas atmosphere,
Next, aluminum alloy foil (JIS-
3003) and rolled at a rolling reduction of 12%, heat treatment was performed in air at a plate temperature of 550°C for 10 seconds to obtain an aluminum laminated steel plate.

Example 3 A 0.5 mm thick steel plate that had been subjected to normal degreasing and pickling treatment was treated with 10og/7 of chromic anhydride and 5/5 of sodium fluoride.
In a solution containing g/l at a temperature of 50°C, using a steel plate as a cathode, treatment was carried out so that metallic chromium and chromium hydrated oxide had a chromium content of 0.1 g/m''.

The treated steel plate and aluminum foil with a thickness of 30 μm were stacked and rolled at a reduction rate of 8%, and the plate was heated to 65% in air.
Heat treatment was performed for 5 seconds at 0'C to obtain an aluminum laminated steel plate.

Example 4 A 0.6 mm thick steel plate that had been subjected to normal degreasing and pickling treatment was treated with 5 g/I of sodium dichromate! temperature including 60
The steel plate was used as a cathode in a solution at 0.degree. C., and treated so that the amount of chromium and chromium oxide was 0.5 g/m2. Next, aluminum alloy foil (J
IS-IN30) were piled up and the whole was rolled at a rolling reduction of 5%, and then heat treated for 30 seconds at a plate temperature of 400°C in a hydrogen gas atmosphere to obtain an aluminum laminated steel plate.

Example 5 Thickness 0.10++++n after normal degreasing and pickling treatment
steel plate, ammonium dichromate 10g/41! In an acidic solution at a temperature of 60°C, the steel plate was treated as an anode so that the amount of chromium oxide was 0.01 g/m2, and then in an atmosphere containing 95% nitrogen gas and 5% hydrogen gas. Then, heat treatment was performed for 30 seconds at a plate temperature of 300°C. Layer the treated steel plate with 50 μm thick aluminum alloy foil (JIS-3004) and
After rolling at a reduction rate of 500℃ in a nitrogen gas atmosphere,
A heat treatment was performed for 30 seconds at ℃ to obtain an aluminum laminated steel plate.

Example 6 A steel plate with a thickness of 0.10 aun that has been subjected to normal degreasing and pickling treatment is treated with chromium chloride 20og/I! , nickel chloride 25g/l! , sodium citrate 50g/I! and a temperature of 40°C containing 130g/l of ammonium chloride.
A chromium-nickel alloy was plated in an acidic solution with a chromium content of 0.5 g/m2 using a steel plate as a cathode. The treated steel plate and aluminum alloy foil (JIS-1085) with a thickness of 100 μm were stacked and rolled at a reduction rate of 5%, and then heat treated for 30 seconds at a plate temperature of 500 ° C in a nitrogen gas atmosphere. An aluminum laminated steel plate was obtained.

For the obtained aluminum laminated steel plate, use a cutter to make a 1 mm square base mark on the aluminum surface until it reaches the base metal part, and then use an Erichsen tester to cut the aluminum side by 6 m.
The process adhesion was tested by protruding 8 mm or 8 mm and forcibly peeling off with cellophane tape.

As a result, in the aluminum laminated steel sheets of Examples 1 to 6 according to the present invention, no peeling of the aluminum or aluminum alloy foil from the steel sheet was observed.

[Effects of the Invention] According to the method for producing an aluminum laminated steel sheet according to the present invention, aluminum or aluminum alloy foil and the steel sheet can be uniformly joined at a low rolling rate, and the diffusion treatment can also serve as softening annealing, improving adhesion.

An aluminum laminated steel plate with excellent workability and work adhesion was economically obtained.

Claims (2)

[Claims] (1) When manufacturing aluminum laminated steel sheets, add chromium, chromium alloy, chromium oxide, or chromium hydrated oxide to the steel sheet in an amount of 0.01 to 0.5 g/m^2.
200-800 in a neutral or reducing atmosphere.
℃ for 1 to 600 seconds, and then the thickness was 5 to 600 seconds.
After laminating 200 μm aluminum or aluminum alloy foils and crimping the whole thing at a reduction rate of 1 to 15%,
A method for producing an aluminum laminated steel sheet, characterized in that heat treatment is performed for 1 to 600 seconds at a temperature from 00°C to less than the melting point of the coated aluminum or aluminum alloy. (2) A method for producing an aluminum laminated steel plate, in which the chromium, chromium alloy, chromium oxide, or chromium hydrated oxide according to claim 1 is coated and then laminated without heat treatment.