Solid State Pressure Welding of Superplastic Zn-22Al Alloy

Abstract

Both the water quenched superplastic and air cooled non-superplastic 78%Zn-22%Al alloy were jointed by means of pressure welding under various conditions. The effects of pressure and welding temperature on the tensile strength and microstructure of the welded joints were investigated. The results obtained were as follows.(1) The joint efficiency of the welded joint of the water quenched materials and that of the welded joint of the air cooled materials increased together with pressure and welding temperature. Under the optimum conditions, the joint efficiencies of the welded joint rose to more than 90%.(2) Comparing the tensile strength of the welded joint of the air cooled materials with that of the joint of the water quenched materials welded under the same condition, the former was found to be larger than the latter.(3) The joint efficency of the welded joint of the water quenched materials and that of the air cooled materials increased nearly 100% and 20% respectively by annealing after welding.(4) The m value of the welded joint of the water quenched materials decreased a little by grain growth during welding, but at the heigher temperature than 440 K, m=0.3∼0.45.(5) In the vicinity of the jointed plane, grain growth was induced during welding, and consequently the hardness was increased.