STUDIES ON WELDBONDING OF ALUMINIUM

Abstract

Lap joints of 1.0 mm thick commercial aluminium sheet are prepared by adhesive joining, resistance spot welding and weldbonding (Combination of adhesive and resistance spot weld) processes. The adhesive joints are prepared using different - surface finish (by different emery grades) and curing for different times at 120°C. During resistance spot welding and weldbonding the welding current and time are varied. The weldbonds are cured at temperature and time of 120°C and 60 min. respectively. The joint properties are studied by shear-tensile ' test. Microstructure of the joints are studied under optical microscope. The nugget size of resistance spot welded and weldbonded specimens are also studied under optical microscope. Hardness of the weld nugget and HAZ in the spot welded and weldbonded specimens are studied. the fatigue properties of the weldbonded specimens are studied. Optimisation of surface roughness and curing time of the adhesive Joints are discussed. The ultimate shear tensile load bearing 'capacity of resistance spot weld and weldbonded joints are compared and correlated with welding parameters. The correlation of the mechanical properties of the joint with their microstructure, nugget size and hardness are discussed. It is observed that at a suitable process parameters weldbond can achieve significantly higher mechanical properties than that , observed in resistance spot weld