Effect of process parameters on tensile strength of friction stir welded cast A356 aluminium alloy joints

A356 is a high strength aluminium-silicon cast alloy used in food, chemical, marine, electrical and automotive industries. Fusion welding of this cast alloy will lead to many problems such as porosity, micro-fissuring, and hot cracking. However, friction stir welding (FSW) can be used to weld this cast alloy without above mentioned defects. An attempt was made to study the effect of FSW process parameters on the tensile strength of cast A356 aluminium alloy. Joints were made using different combinations of tool rotation speed, welding speed and axial force. The quality of weld zone was analyzed by macrostructure and microstructure analyses. Tensile strengths of the joints were evaluated and correlated with the weld zone hardness and microstructure. The joint fabricated using a rotational speed of 1000 r/min, a welding speed of 75 mm/min and an axial force of 5 kN showed a higher tensile strength compared to the other joints.