Weldbonding of Stainless Steel.

Abstract

Lap joints of 1.0 mm thick austenitic stainless steel sheets were prepared by adhesive bonding, conventional resistance spot welding and weldbonding processes. The weldbonding was carried out by adhesive joining followed by resistance spot welding of two pieces and immediate curing at temperature of 120°C for 60 min. The same schedule of curing was also applied in preparation of adhesive joints of the sheets. Prior to joining, the faying surfaces of the two sheets were always polished with 400 grade emery paper. The thickness of adhesive layer resulting maximum shear-tensile load bearing capacity of the joint was optimised. The size of weld nugget, microstructures of the weld and HAZ and hardness of the nugget and HAZ, resulted from different welding parameters (current and time), in both the resistance spot welds and weldbonds were studied. The ultimate shear-tensile load bearing capacity of the resistance spot welds and weldbonds are also compared and correlated with the welding parameters. The fatigue properties of the resistance spot weld and weldbond, having maximum strength, were also tested. The fracture behaviour of all the three types of joints was studied under optical stereo microscope. The weldbonds prepared at optimum process parameters were found to have superior mechanical properties than those of the conventional resistance spot welds, especially under dynamic loading.