JP2543430B2 - Aluminum laminated steel sheet manufacturing method - Google Patents

Description

The present invention relates to a method for producing an aluminum laminated steel sheet by roll reduction and heat treatment.

[Prior Art] Aluminum has excellent properties such as light weight, good workability and high corrosion resistance, and the improvement of mechanical properties by containing other metals. In terms of mechanical strength, it is inferior to other materials such as steel. In order to impart the characteristics of steel to this aluminum, the development of a clad material of aluminum and steel is under way.

Although several methods are known for joining aluminum and steel, joining by cold rolling and hot rolling is suitable for continuous production of plates or foils. Of these, joining by cold rolling (JP-A-56-109183 and JP-A-
No. 58-141882) has been studied a lot, but when heat treatment is applied to improve the bonding strength or to improve the mechanical properties, a fragile alloy layer composed of aluminum and iron grows, Workability is reduced.

As a method for solving this drawback, a method in which a heat diffusion treatment is unnecessary at a low pressure reduction rate by performing ion etching with a non-oxidizing low pressure gas such as argon to remove oxides and then reducing the pressure (Japanese Patent Laid-Open No. 1-224184) No.), or a method of inserting and reducing an insert material such as nickel or copper at the joint interface to suppress the formation of a brittle alloy that forms during heat treatment; No. 1-264856), and a layer containing chromium as a main component (Japanese Patent Application No. 2-16038) and a layer containing molybdenum as a main component (Japanese Patent Application No. 2-16039) are applied to the bonding interface to reduce rolling. There is a way to do it.

[Problems to be Solved by the Invention] When aluminum and steel having greatly different plastic deformation amounts are joined by a cold rolling method, in order to obtain a sufficient joining force, it is necessary to perform a heat treatment as a diffusion treatment after rolling. However, the brittle alloy grows at the interface, which causes the workability of the laminated steel sheet to deteriorate. One of the methods to solve this drawback is to use an insert material to suppress alloy formation, but the handling of the insert material requires a thickness of 10 μm or more, which is economically inferior. Also, the oxide of aluminum foil or plate and steel plate is removed by ion etching,
Methods that eliminate the need for heat diffusion processes that cause the formation of brittle alloys require vacuum equipment and techniques,
There is a problem in terms of economy. Furthermore, in order to suppress the formation of brittle alloys at the bonding interface, nickel, nickel,
There is a method of applying a plating layer of copper, a method of applying a layer containing chromium as a main component, and a method of applying a layer containing molybdenum as a main component, but these methods are basically applied to the cold rolled steel sheet surface after softening annealing. In the entire process of producing a laminated steel sheet, softening annealing of the steel sheet after cold rolling, heat treatment for the purpose of improving the uniformity of bonding during lamination, and
A total of three or more heat treatments for heat diffusion treatment to improve the bonding strength are required.

[Means for Solving the Problems] The present invention provides a method for producing an aluminum laminated steel sheet having excellent adhesion, workability, and processing adhesion by performing heat diffusion treatment after pressure bonding, and in the method of softening annealing and lamination. By simultaneously performing heat treatment for improving the uniformity of bonding, it is an object to reduce the number of heat treatment steps and to provide economically.

The gist is that the cold-rolled steel sheet before softening annealing is coated with nickel, an alloy containing nickel as a main component, chromium or an alloy containing chromium as a main component, or a plurality of them, and then neutralized or reduced. In an atmosphere, heat treatment is carried out for the purpose of improving the uniformity of softening annealing and joining after lamination, and then aluminum foil or aluminum alloy foil is superposed on the steel sheet, and the whole is pressed and pressure-bonded and then heat-treated again. Then, the aluminum laminated steel sheet coated with aluminum foil or aluminum alloy foil on one side or both sides is manufactured by diffusion bonding.

The cold-rolled steel sheet of the present invention is a steel sheet obtained by cold-rolling a hot-rolled steel sheet, and includes, for example, a low carbon steel sheet, a chromium-added steel sheet, and a nitrogen-added steel sheet. Further, the plate thickness can be freely selected according to the intended use after manufacturing.

On the other hand, the aluminum foil 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 workability decreases with a foil of less than 5 μm, which is not suitable for high-speed production.
If the thickness exceeds 200 μm, it is uneconomical in terms of material costs.

At the time of production, the joint surface of the steel sheet contaminated with rolling oil or the like immediately after cold rolling is cleaned by degreasing and pickling. Degreasing is performed with an alkaline solution by dipping treatment or cathodic or anodic electrolytic treatment. In this case, the processing conditions such as liquid composition, liquid concentration, processing temperature and processing time are not particularly limited, but electrolytic processing is suitable for continuous processing. The pickling is a treatment for removing the scale on the surface of the steel sheet, but the conditions of this pickling are not particularly limited.
However, excessive treatment causes hydrogen absorption in the steel sheet, and swelling or the like occurs during diffusion heating after pressure bonding, which impairs the uniformity of bonding. Further, if the degreasing and pickling treatments are insufficient, it is difficult to obtain an aluminum-laminated steel sheet having sufficient bonding strength due to poor adhesion of the treated film thereafter.

The joint surface of this steel sheet is coated with nickel, an alloy containing nickel as a main component, chromium, an alloy containing chromium as a main component, or a plurality of them. The method of coating is not particularly limited, but electroplating is suitable and economical for continuous treatment. Nickel-based alloys include nickel and phosphorus, cobalt, copper, zinc, tin or iron alloy platings or composite platings, and chromium-based alloys include chromium-zinc or iron alloy platings. Alternatively, it does not matter if it includes composite plating and contains chromium oxide and hydrated chromium oxide. At this time, the total coating amount is preferably 0.05 to 30 g / m ² . Here, the coating amount is limited to less than 0.05 g / m ² ,
A sufficient improvement effect is not recognized, and if it exceeds 30 g / m ² ,
This is to reduce the bonding force.

Then, in a non-oxidizing atmosphere represented by hydrogen, nitrogen, or argon, the steel sheet is heated to 500 to 800 ° C at 10 ° C.
Heat treatment is carried out under the soaking conditions of ~ 200 seconds or 400 ~ 700 ° C for 1 ~ 15 hours. The former uses heating means like a continuous annealing furnace, and the latter uses heating means like a box-type batch annealing furnace. This heat treatment is softening annealing for improving the mechanical properties of the steel sheet deteriorated by cold rolling, and also serves to improve the uniformity of bonding during lamination. Improving the uniformity of joining means that when nickel, nickel alloy, chromium or chromium alloy is coated on the steel sheet by electroplating method, gas or liquid such as hydrogen absorbed or adsorbed is heated and released from the steel sheet. This suppresses the formation of blisters that occur during the heat diffusion treatment after pressure bonding. Further, nickel or chromium diffuses into the steel by this heat treatment, and suppresses corrosion from minute pinholes existing in the aluminum foil or aluminum alloy foil after lamination.

Desorption of gas or liquid is possible even if heat treatment is performed under the conditions below the temperature and time described, but the mechanical properties of the steel sheet are improved, and diffusion treatment of nickel, nickel alloy, chromium or chromium alloy is performed. Is not enough for Further, if the heating condition exceeds the stated range, the effect is saturated.

The heat-treated steel sheet and aluminum foil or aluminum alloy foil are overlaid, and the entire reduction rate is 1 to 80.
Roll down in%. The rolling reduction depends on the thickness and hardness of the steel sheet and the aluminum foil or aluminum alloy foil used, but a sufficient rolling force cannot be obtained with a rolling reduction of 1% or less. If the reduction rate is increased to 80% or more, it may cause wrinkles or blurring of the foil. When the laminated steel sheet is required to have good working characteristics, a reduction rate of 10% or less is suitable. If the rolling reduction is 15% or more, the effect of rolling and thinning the entire laminated steel sheet becomes large. A plurality of reductions may be performed to obtain a predetermined reduction rate. At this time, the aluminum foil or aluminum alloy foil can be coated on both sides or one side of the steel sheet, but when symmetrically laminated and rolled down, the difference in plastic deformation rate during crimping or linear expansion rate during heating is different. The warp caused by can be eliminated.

Then, in order to impart good adhesion to the laminated steel sheets bonded by reduction, at 1 to 60 at a temperature lower than the melting point of the coated aluminum foil or aluminum alloy foil from 350 ° C.
A heat diffusion process for 0 seconds is performed. If it is less than 350 ° C and less than 1 second, the effect of improving the adhesion is weak. Joining takes more than 600 seconds, but the effect saturates. For continuous high-speed production, 60 seconds or less is preferable. The atmosphere of this heat treatment is not particularly limited,
You may heat in air. Further, the pressure applied during heating is not particularly limited.

[Operation] A strong oxide film is present on the surface of the aluminum foil or aluminum alloy foil, but when it is rolled down by overlapping with a steel plate, this oxide film is destroyed at the joint surface and the new surface is exposed. There is no need to perform processing to remove the oxide film. Further, the nickel and chromium coated on the steel sheet cover the defective portion on the surface of the steel sheet and suppress the growth of the brittle iron-aluminum alloy generated during heating, so that an aluminum laminated steel sheet excellent in work adhesion is obtained. It is thought to be done. Furthermore, the heat treatment performed prior to crimping is, in addition to softening annealing for improving the mechanical properties of the steel sheet, preheating for desorption of gas or liquid such as hydrogen absorbed or adsorbed by electric treatment, and
It also has three functions of diffusion of nickel or chromium into steel that increases the corrosion resistance when pinholes occur in aluminum foil or aluminum alloy foil. Compared with the conventional method in which softening annealing and preheating were individually performed. Therefore, it is possible to reduce the heat treatment process, which enables more economical manufacturing.

[Examples] The present invention will be specifically described with reference to Examples.

Example 1 Thickness 0.30 before softening annealing produced by ordinary cold rolling
mm cold-rolled steel sheet was degreased in an aqueous solution containing sodium hydroxide as the main component, pickled in a sulfuric acid aqueous solution, and then treated with chromic anhydride 10
In a solution containing 0 g /, 5 g / sodium fluoride at a temperature of 50 ° C, the current density of 4000 A / m ² is used as a cathode, and the chromium metal is 0.1 g / m in terms of chromium content. ²
Was processed so that 95% nitrogen in a steel plate that has been subjected to this treatment
In an atmosphere containing hydrogen and 5% hydrogen, the plate is heated at a temperature of 600 ° C for 60 seconds, and then an aluminum foil with a thickness of 20 µm is stacked, and after pressing with a 5% reduction ratio, the plate temperature is 400 in air.
Heat treatment was performed for 60 seconds under the condition of ° C to obtain an aluminum laminated steel sheet.

Example 2 Thickness of 0.60 before softening annealing produced by ordinary cold rolling
mm cold-rolled steel sheet is degreased in an aqueous solution containing sodium orthosilicate as a main component, pickled in a sulfuric acid aqueous solution, and then used in a Watt bath (240 g / of nickel sulfate, 45 g / of nickel chloride, 3 boric acid).
0g /) at a temperature of 50 ° C and a current density of 1000A / m ² and plated with 1g / m ² of nickel, nitrogen gas 95% and hydrogen gas 5
%, The plate was heated at 700 ° C. for 20 seconds under the soaking condition. Then, an aluminum alloy foil (JIS-3004) with a thickness of 60 μm was overlaid, pressure-bonded at a reduction rate of 10%, and then heat-treated in the air at a plate temperature of 500 ° C. for 30 seconds to obtain an aluminum laminated steel sheet. .

Example 3 Thickness of 0.20 before softening annealing produced by ordinary cold rolling
After cold degreasing and pickling on a cold rolled steel sheet of mm, it is dipped in a solution containing nickel chloride 30 g /, sodium hypophosphite 30 g /, and sodium acetate 10 g / at a temperature of 90 ° C. After the alloy plating is converted to nickel and plated at 10 g / m ² , the plate temperature is 550 ° C in an argon gas atmosphere.
It heat-processed for 200 seconds on the conditions of. Next, after stacking aluminum foil having a thickness of 5 μm and press-bonding with a reduction rate of 3%,
A heat treatment was performed for 20 seconds in an argon gas atmosphere at a plate temperature of 600 ° C to obtain an aluminum laminated steel plate.

Example 4 0.50 thickness before softening annealing produced by ordinary cold rolling
After cold degreasing and pickling on a cold rolled steel sheet of mm, nickel was sequentially plated at 5 g / m ² and chromium at 0.1 g / m ² . Then
The steel sheet was heat-treated in a nitrogen atmosphere at a temperature of 500 ° C. for 200 seconds, cooled, and then laminated with an aluminum alloy foil (JIS-5052) having a thickness of 100 μm, and continuously rolled down three times. , And crimped at a reduction rate of 30%. Then, heat treatment was performed for 200 seconds in a hydrogen atmosphere at a plate temperature of 350 ° C. to obtain an aluminum laminated steel plate.

Example 5 Thickness of 1.0 m before softening and annealing produced by ordinary cold rolling
The cold rolled steel sheet of m was subjected to usual degreasing and pickling, and then plated with chromium at 0.1 g / m ^{2 and} then at 5 g / m ² of nickel-zinc composite plating. This steel sheet is heat-treated in an atmosphere containing 95% nitrogen and 5% hydrogen at a plate temperature of 600 ° C. for 10 seconds under the soaking condition, and after cooling, a 200 μm-thick aluminum foil is laminated and rolled five times. A reduction was applied and a compression rate of 70% was applied. Then, heat treatment was performed for 30 seconds in an atmosphere containing 95% nitrogen and 5% hydrogen at a plate temperature of 500 ° C. to obtain an aluminum laminated steel sheet.

Example 6 Thickness of 0.80 before softening annealing produced by ordinary cold rolling
After cold degreasing and pickling on a cold rolled steel sheet of
The composite plating of copper 5 g / m ² applied, then in an atmosphere containing 95% and 5% of hydrogen nitrogen, the temperature 550 ° C. of the plate, heated in soaking conditions for 5 hours, the aluminum foil after cooling, thickness 30μm Were piled up and pressure-bonded at a rolling reduction of 7%. Then 95% nitrogen
Then, heat treatment was performed for 60 seconds at a plate temperature of 400 ° C. in an atmosphere containing hydrogen and 5% of hydrogen to obtain an aluminum laminated steel plate.

Example 7 Thickness of 0.60 before softening annealing produced by ordinary cold rolling
After cold degreasing and pickling on a cold rolled steel sheet of mm, nickel plating is performed at 150 g / m ² and then heat treatment is performed in an argon atmosphere at a plate temperature of 400 ° C. for a soaking time of 15 hours, After cooling
Aluminum alloy foil (JIS-3004) having a thickness of 100 μm was overlaid and pressure-bonded at a rolling reduction of 5%. Then, heat treatment was performed for 60 seconds in the air at a plate temperature of 600 ° C. to obtain an aluminum laminated steel plate.

The obtained aluminum laminated steel plate is 1 m with a cutter on the foil
After attaching a square of m squares until reaching the steel plate, the evaluation of the adhesion is as it is, and the evaluation of the processing adhesion is overhanging the aluminum side by 6 mm or 8 mm with an Erichsen tester,
Each was tested by forcibly peeling it off with an aluminum foil or an aluminum alloy foil with an adhesive tape.

As a result, in the aluminum laminated steel sheets according to the present invention of Examples 1 to 7, no peeling of the aluminum foil or aluminum alloy foil from the steel sheet was observed.

[Effect of the Invention] By the method for producing an aluminum laminated steel sheet according to the present invention,
Aluminum foil or aluminum alloy foil and steel sheet are evenly joined, softening annealing of cold-rolled steel sheet, pre-heating treatment for improving uniformity of joining after lamination, and improvement of corrosion resistance of pinhole part of foil It is possible to simultaneously perform three types of heat treatments, that is, diffusion treatment of meaningful nickel and chromium into steel, and economically obtain an aluminum laminated steel sheet excellent in adhesion, workability and work adhesion.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-63-40689 (JP, A) JP-A-53-102840 (JP, A) JP-A-3-128180 (JP, A) JP-A-3- 221274 (JP, A) JP-A-3-221273 (JP, A) JP-A-3-221275 (JP, A) JP-A 63-235083 (JP, A) JP-B-34-5408 (JP, B1) Japanese Examined Sho 37-70 (JP, B1)

Claims (2)

(57) [Claims] 1. When manufacturing an aluminum laminated steel sheet, 0.05 or more of nickel, a nickel alloy, chromium, a chromium alloy, or a plurality thereof are added to a cold rolled steel sheet before softening annealing.
~ 30g / m ^{2 After} coating, heat treatment in neutral or reducing atmosphere at 500-800 ℃, soaking condition for 10-200 seconds,
Next, a method for manufacturing an aluminum laminated steel sheet, which comprises laminating aluminum foil or aluminum alloy foil, press-bonding the whole, and then performing heat diffusion treatment. 2. When manufacturing an aluminum laminated steel sheet, 0.05 or more of nickel, a nickel alloy, chromium, a chromium alloy, or a plurality thereof is added to a cold rolled steel sheet before softening annealing.
After to 30 g / m ² coated, in a neutral or reducing atmosphere, 400 to 700 ° C., subjected to heat treatment in soaking conditions 1 to 15 hours,
Next, a method for manufacturing an aluminum laminated steel sheet, which comprises laminating aluminum foil or aluminum alloy foil, press-bonding the whole, and then performing heat diffusion treatment.