JPH10180464A - Manufacture of copper-stainless steel clad plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the bonding strength by performing the heating and diffu sion treatment under the prescribed conditions after the pressure welding through the cold rolling of the prescribed draft in manufacturing the copper-stainless steel clad plate to be used for an oil cooler for vehicle. SOLUTION: Brushed bonding surfaces of a copper plate and a stainless steel plate are overlapped with each other to perform the cold rolling of the draft of 2-10%, and after the pressure welding, the heating treatment for >=2 hours at 500-1000 deg.C under the vacuum of <=10<-4> Torr. is performed. The draft is expressed by (t0 -t)/t0 (%), where t. is the sum of the thickness of the copper plate and the stainless steel plate, and (t) is the thickness of the clap plate after rolling. The peeling strength of >=20 N/mm can be obtained. The brushing treatment of the bonding surfaces is performed by a rotary wire brush provided with alumina or silica particles, and the surface roughness Ra measured in the direction orthogonal to the brush is preferably >=0.12 μm. When Ra is <=0.12 μm, no mechanical anchoring effect by rolling can be expected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a Cu-stainless steel clad plate. More specifically, the present invention relates to a clad plate used for an oil cooler material for automobiles, a container material, and the like.

[0002]

BACKGROUND OF THE INVENTION Cu-stainless steel clad plates are relatively demanding composite materials, for example, used as containers and electronic materials, but their high cost has hindered their further spread. In general, a Cu-stainless steel clad plate is manufactured by subjecting a joining surface to cold brushing treatment, then overlapping the joining surfaces, and performing cold rolling at a rolling reduction of 60% or more. Brushing is performed for the purpose of removing oils and fats and oxides on the surface that impairs the bondability, securing a new surface, and further improving the bondability by giving surface distortion. However, in such a conventional method, if brushing is excessively performed in order to sufficiently realize surface activation, the material may be damaged, and mechanical properties may be deteriorated.

Further, since the rolling load during cold rolling at a rolling reduction of 60% or more is considerably high, it is difficult to produce a wide clad plate by this method. The width of the pressure welding material that can be produced by this method is usually 300 mm or less, and at most 600 mm. Since it is difficult to manufacture wide products, productivity and yield are not good, and this is a factor that increases the manufacturing cost of clad plates. In order to reduce the manufacturing cost of the clad plate, it is important to reduce the cost required for forming the clad rather than the material cost.

Japanese Patent Publication No. 41-21975 discloses a high purity hydrogen atmosphere (hydrogen purity 99.99999% or more, dew point -70 ° C or less).
At 600 ° C or more while applying a pressure welding external force of ² kg / cm ² or more,
A method is disclosed in which copper and stainless steel are adhered by heating and holding at a temperature not higher than the melting point of copper (1083 ° C.). However, in this method, high-purity hydrogen is required, and it is necessary to apply a high pressure welding external force during high-temperature heating, which is lacking in economy and mass productivity. This method is applicable only to small-sized plate materials, and it is also difficult to apply the method to manufacturing long plate materials.

JP-A-2-34288 discloses that two or more types of thin plates constituting a clad plate and a thin plate of heat-resistant steel acting as a release material are wound in a coil shape on a steel core having a high coefficient of thermal expansion, and a vacuum is formed. A method for producing a clad plate which is annealed and diffusion-bonded is disclosed. However, in this manufacturing method, the joining pressure required for joining mainly depends on the difference in the coefficient of thermal expansion between the materials constituting the core metal and the coil. In this method, fluctuations in the dimensional accuracy of the material constituting the coil and fluctuations in the tension at the time of coil winding affect the bonding properties, so that a good bonding strength is stably secured in the width and length directions of the clad plate. It is difficult.

[0006] Japanese Patent Application Laid-Open No. 4-228278 discloses that the joining surface of a copper plate and a stainless steel plate is warm brushed and warm-rolled for joining or, if necessary, heat-treated and inter-diffused for joint strength. Are disclosed. However, in this method, the temperature drop during the brushing process is severe,
Since the joining is performed at a low temperature, the joining becomes unstable and the rolling load becomes too large, which is unsuitable for producing a wide material.

Japanese Patent Application Laid-Open No. 4-266490 discloses a method in which a Cu plate and a stainless steel plate wound in a coil shape under tension are subjected to diffusion bonding by heating in a non-oxidizing atmosphere. However, in this method, similarly to the method described in Japanese Patent Application Laid-Open No. 2-34288, the tension fluctuation in the coil length direction and width direction at the time of coil winding affects the bonding strength, so that a stable and good bonding state is obtained. Is difficult to get.

As described above, a method capable of efficiently and economically producing a Cu—stainless steel clad plate and applicable to a long and wide material has not yet been disclosed.

[0009]

An object of the present invention is to provide an economical method for producing a wide-width Cu-stainless steel clad plate having a uniform joining strength over the entire coil.

[0010]

The gist of the present invention is as follows:
u-The method for manufacturing a stainless steel clad plate.

[0011] After the Cu plate and a stainless steel plate brushed treated joint faces superimposed and combined with pressure by performing rolling reduction 2-10% cold rolled sheet, 10 ^-4 Tor
r A method for producing a Cu-stainless steel clad plate, characterized by heating to 500 to 1050 ° C. in the following vacuum.

Where, the rolling reduction = {(t ₀ −t)} t ₀ } × 100 (%) t ₀ : the sum of the thickness of the Cu plate before rolling and the thickness of the stainless steel plate t: the thickness of the laminated plate after rolling The present invention has been completed based on the following new findings regarding the joining phenomenon between copper and stainless steel.

[0013] By joining and cold-rolling the joining surfaces of Cu and stainless steel, each of which is provided with appropriate irregularities on the surface to be joined by the brushing process, the mechanical anchoring effect due to the irregularities on the surface allows the width and length to be increased. A laminated plate having a superposed shape that is uniform in the width direction without slack is obtained. The rolling reduction at this time may be low. When the laminated plates uniformly overlapped in the width direction and the length direction are heat-treated in a non-oxidizing atmosphere, a Cu—stainless steel clad coil having a uniform bonding strength can be obtained.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method for producing a Cu-stainless steel clad plate of the present invention is as follows.

Pretreatment: width direction by mechanical anchoring effect,
The joining surface between the Cu plate and the stainless steel plate before cladding is subjected to a brushing treatment so that a laminated plate having no slack in the length direction can be obtained by light cold rolling. This treatment is for the purpose of cleaning the joint surface and forming irregularities on the joint surface, and it is preferable to use a rotating brush. In order to obtain the mechanical anchoring effect necessary to form a plywood by light rolling, which will be performed later, the degree of unevenness formed on the bonding surface is determined by using a rotating brush on both the Cu plate and stainless steel plate. It is preferable that the surface roughness Ra measured in the direction perpendicular to the above is 0.12 μm or more. If Ra is less than 0.12 μm, the mechanical anchoring effect after rolling cannot be secured. The brush material, number of revolutions, rolling force, etc. are not particularly specified.However, in order to efficiently clean the joint surface and impart irregularities, for example, the brush material should be made of alumina or silica which has excellent wear resistance. It is preferable to use a wire brush or the like having particles of It is desirable that the surface to be joined after the brushing be cleaned so that no grinding dust or the like remains. After the surface is washed with water or the like, it is dried with, for example, hot air.

Cold rolling: A Cu plate and a stainless steel plate whose surfaces to be joined are brushed are cold-rolled so that the joining surfaces are joined together, and are pressed together in a shape without slack in the width and length directions. Processed into a plate. The cold rolling reduction at this time is in the range of 2 to 10%. When the rolling reduction is less than 2%, the mechanical anchoring effect due to the indentation of the surface irregularities is not exhibited, and there is a possibility that the copper and the stainless steel sheet may be loosened. If the rolling reduction exceeds 10%, the length difference between the Cu plate and the stainless steel plate in the longitudinal direction will increase due to the difference in deformation resistance, and there will be slack between the two and the unevenness of the surface will be rolled and the surface will change to a smooth surface. Then, the mechanical anchoring effect is reduced. In order to prevent meandering during rolling, during rolling, 5-150
It is desirable to roll under tension in the range of N / mm ² .
Rolling is performed without lubrication. Rolls have a surface roughness Ra of 0.1
It is desirable to use one with a smooth surface of μm or less. The rolling speed and other conditions are not particularly limited and can be implemented.

Heat treatment: The combined plate is vacuumed to 500 ~
Diffusion bonding is performed by heating in a temperature range of 1050 ° C. for 2 hours or more. Cu is a metal having a remarkably high affinity for oxygen even at a low temperature, and when heated in an oxidizing atmosphere, a strong oxide layer of CuO is formed on the surface of Cu to hinder the bonding. In order to avoid this, it is necessary to perform the heat treatment in a vacuum having a degree of vacuum of 10 ^-4 Torr or less.

If the heat treatment temperature is too low, metal bonding due to interdiffusion of Cu and Fe hardly occurs, and a desired bonding strength cannot be obtained. Therefore, the lower limit of the heat treatment temperature is 500
° C. If the heat treatment temperature is excessively high, there is a possibility that the stainless steel sheet which is in contact with the Cu plate and which is not to be joined is fused. If such a phenomenon occurs, a good clad plate cannot be obtained. To avoid this, the upper limit of the heat treatment temperature is set to 1050 ° C. The time to be kept in this heat treatment temperature range is 2 hours or more in order to sufficiently perform diffusion bonding. The upper limit of the holding time is not limited, but is preferably shorter from the viewpoint of economy. The heating rate up to the heat treatment temperature and the cooling rate after the end of the heat treatment are optional.

In the production method of the present invention, the treatment may be carried out on a cut plate-shaped steel plate, but it is efficient to carry out the treatment in a long coil shape. There is no particular restriction on the thickness or width of the copper or stainless steel to be clad, and the method of the present invention is applicable as long as the above-mentioned brushing treatment and rolling can be performed. Further, as a Cu plate as a material to which the manufacturing method of the present invention can be applied, pure Cu or a Cu alloy specified by JIS H 3100 and made of Cu, Zn, Al, or the like can be used. The stainless steel sheet as the material may be a general stainless steel sheet, and for example, various kinds of cold-rolled stainless steel sheets such as various ferrite-based, austenitic-based or austenitic-ferrite-based steels specified in JIS G 4305 can be used.

[0020]

【Example】

(Example 1) Oxygen-free copper plate (C1020) having a thickness of 0.3 mm and a width of 700 mm specified in JIS H 3100
A clad steel sheet was manufactured using the austenitic stainless steel sheet (SUS304) specified in P) and JIS G 4305 under the following conditions. The surfaces to be joined of the copper plate and the stainless steel plate are subjected to a brushing treatment using a brushing device provided on the entry side of the cold rolling mill, and the joined surfaces are overlapped and cold-rolled at a rolling reduction of 1 to 12%. Then, they were pressed against each other and wound around a coil. Rear tension during the cold rolling brushing, 20 N per width 1 mm ² in the copper plate, and 28N per width 1 mm ² in the stainless steel plate, front tension to clad plate was 48N / mm ^2. Brush material is SiC
The surface roughness (Ra) measured in the width direction of the plate after the brushing treatment is 0.25 μm for copper and 0.25 μm for stainless steel plate.
Met. The wound coil is heated to several temperature levels between 500 and 1050 ° C. in a vacuum of 10 ^-6 Torr vacuum.
A heat treatment for holding for a time was performed to obtain a clad plate. Also,
For comparison, a case of holding at 450 ° C. for 2 hours in the same vacuum was also performed.

The bonding strength of the obtained clad plate is JIS K
The evaluation was performed according to the T-peel test described in 6854. 10m width
The test was performed at a pulling speed of 180 mm / min using a peel test piece having a length of 150 mm and a length of 150 mm. The test pieces were sampled at positions 10 mm inside from the front and rear ends in the longitudinal direction of the coil and both ends in the width direction at the center. The peel strength is 20N per 1mm width (hereinafter, 20N
N / mm or more), peeling does not occur at the time of press working, so that those having a peel strength of 20 N / mm or more were judged to have good bondability. Table 1 shows the results of these tests.

[0022]

[Table 1]

In the evaluation column of Table 1, the peel strength is 20 N / mm.
The above was evaluated as ○, and the one less than 20 N / mm was evaluated as ×.
As shown in Table 1, the clad plates described in Test Nos. 1 to 9 manufactured by a method satisfying the conditions specified in the present invention are:
In each case, the peel strength was 20 N / mm or more, and it was confirmed that the bonding strength was high. On the other hand, as comparative examples, the bonding strength of the clad plates of Nos. 10 to 12 manufactured by a method not satisfying the conditions specified in the present invention was not preferable.

[0024]

According to the method of the present invention, a Cu-stainless steel clad plate having a uniform joining strength over the entire coil can be efficiently and economically manufactured.

Claims (1)

[Claims] [Claim 1] After the Cu plate and a stainless steel plate brushed treated joint faces superimposed and combined with pressure by performing rolling reduction 2-10% cold rolled sheet, 10 ^-4 Tor
r A method for producing a Cu-stainless steel clad plate, characterized by heating to 500 to 1050 ° C. in the following vacuum. Here, the rolling reduction = {(t ₀ −t)} t ₀ } × 100 (%) t ₀ : the sum of the thicknesses of the Cu plate and the stainless steel plate before rolling t: the thickness of the laminated plate after rolling