Investigation of Mechanical Properties of Friction Stir Welded pure Copper Plates

Abstract

In conventional welding process, copper and copper alloys are difficult to welding because of high thermal conductivity and high melting point of copper. Due to high melting point, more amount of heat is required to weld the copper and due to high thermal conductivity, heat effected zone in the welded component increases so loses its mechanical and thermal properties. Friction stir welding is a new method that resoles the all above problems. Friction stir welding is a solid state joining process welding done at below the recrystallization temperature. The joint technique is a energy efficient, the environment friendly, easy and defect free welding process.Purpose of this study is to find out the optimum mechanical properties of the friction stir welding of copper. Present study entails an attempt has been made to study the effect of tool rotational speed, traversing speed and tool pin profiles (straight cylindrical profile) on FSP zone transformation in copper. For two different tool rotational speeds, two different traversing speeds, one tool pin profiles have been used to fabricate the joints. The formation of FSW of copper of fusion zone has been evaluated and correlated with base metal. Tensile strength, toughness, hardness and microstructure of the joint evaluated and Tensile strength correlated with weld zone hardness and microstructures. The joints fabricated using rotational speed of 910 rpm, a welding speed of 30mm/min, tool pin with square profile, tool shoulder diameter of 34mm, (Ds/Dp)=3 showed higher tensile strength compared to other joints at a constant load.The experimental results showed that the fracture locations of the joints are affected by FSW parameters, where copper joints are fractured in TMAZ and or in NZ/TMAZ interface on the retreating side of the welds and all fracture locations are nearer to the weld centres.