Effect of Preheating on Mechanical Properties and Microstructural Behaviour of Friction Stir Welded Copper Joints

Copper has a wide range of applications because of its great thermal and electrical conductivity, corrosion and fatigue resistance, and good flexibility. In this paper, the effect of preheating on the mechanical properties of similar friction stir welded plates were investigated. Copper plates were preheated at 450, 550 and 650°C and welded at a rotational speed of 600rpm, a constant transverse speed of 400 mm/min, and a plunge depth of 3,5mm using a cylindrical pin profile. The welded samples were characterized by optical microscope. Tensile and hardness tests were conducted following the ASTM E8-04 and ASTM E92- 82 respectively. The results showed the stir zone consists of fine and equiaxed recrystallized grains with precipitates compared to the parent material. The effect of preheating showed a decrease in the tensile strength of the joint. The average hardness of 650 °C preheated weld joint was reported be the highest as compared to the other joints.