Effect of pre-hole offset on the property of the joint during laser-assisted friction stir welding of dissimilar metals steel and aluminum alloys

In this paper, the influence of pre-hole offset distance on the properties of the welding joint during laser-assisted friction stir welding of Q235 steel and 6061-T6 aluminum alloy was studied. The tensile strengths of the joints obtained at different pre-hole offset distances are tested and compared. SEM, EDS and an optical microscope are used to analyze the compositions of the inter-metallic compounds and the metallographic structure of the joints, respectively. Results show that the pre-hole offset distance, the thickness of the inter-metallic compounds layer and the type of the inter-metallic compounds are the key factors that affect significantly the tensile strength of the joints in laser-assisted friction stir welding of steel and aluminum alloy. The tensile strength of joints can be easily guaranteed under such conditions as a proper pre-hole offset distance is used, thin inter-metallic compounds layer and iron-abundant inter-metallic compounds are formed.