The Effect of Welding Parameters on Friction Stir Butt Welds of Copper Plates

The main objective of this study is experimental investigation on the effect of welding parameters on friction stir butt welds of copper plates. The defect-free welds were obtained on 4-mm thick copper plates at a wide range of rotational and traverse speeds using a special tool that has non-threaded pin. The tensile tests showed the welded copper joints have high efficiency and some welds gained 90% weld efficiency as compared to the parent copper.The hardness tests and micro-structural analysis showed that heat-affected zone (HAZ) is formed around the stir zone. This zone has lowest hardness and all of the transvers tensile test specimens were fractured in this zone. Furtheremore a novel surface hardness mapping technique was applied in the present work. This experiment showed that different points on the stir zone have very different hardness values, and weld strength is proportional to the lowest hardness in weld zone.