Cold welding : Experimental investigation of the surface preparation methods

This paper presents a systematic experimental investigation for cold welding of five different metal combinations- Al-Al, Cu-Cu, steel-steel, Al-Cu and Al-steel - applying seven different surface preparation methods, including anodizing of Al, semibright electrolytic Ni plating, electroless Ni plating, heat-treated electroless Ni plating, electrolytic hard Cr plating, scratch brushing and degreasing with acetone. After roll welding with varying reductions, the weld strength was tested by a shear test system developed in the present work. The weld strength curves for alternative methods of surface preparation were compared for each metal combination. It was found that different surface preparation methods resulted in different weld strengths. The semibright Ni plating and electroless Ni plating are optimum for Al-Al, electroless Ni plating for Cu-Cu, heat-treated electroless Ni plating for steel-steel, and scratch brushing for Al-Cu and Al-steel.