| 摘要 |
PURPOSE:To obtain the clad bar which does not cause swelling in the heat-treatment process after pressure welding by cleaning the respective bonding faces of dissimilar metal bars, one of which is a base material and the other is a covering material, then interposing the specific metal layer and superposedly rolling the same cold. CONSTITUTION:In producing the clad bar composed of dissimilar metals by using gold, silver, copper and nickel and their alloys without containing zinc and tin, the respective bonding faces of the base material and covering material are beforehand cleaned through brushing and activated, after which they are superposed with interposition therebetween of zinc or alloy of a zinc content 10% or over or tin or alloy of a tin content 25% or over and the laminate is passed cold through rolling rolls, whereby these materials are pressure welded. When the resultant clad bar is heated and annealed in a nitrogen atmosphere, the fine defects on the bonding surface disappear owing to the diffusion effect of the interposing metal layer to have higher pressure weldability and therefore there is no likelihood for the production of swelling in annealing process. |
