Effect of tool insert speed and preheating time on mechanical properties of friction stir welded 5052 aluminum alloy joint

5052-H34 aluminum alloy plate with 5 mm in thickness was friction stir welded using a numerically controlled friction stir welder. The effects of tool insert speed and preheating time on the microstructures and mechanical properties of friction stir welded joint were investigated. Regardless of welding conditions, the microstructures of stir zone showed finer than that of the base metal. In case of tool insert speed 90 mm/s and preheating time 0.1 s, the kissing bond was observed in the bottom of weld interface of joint. However, preheating time more than 5 s, kissing bond was not observed in bottom of weld interface of joint. The hardness of heat affected zone was softer than that of the base metal. The heat affected zone became narrow in conditions of tool insert speed 90 mm/s and preheating time 0.1 s. Maximum tensile strength of start position of joint was 205 MPa, and it was 83% of base metal. The conditions were tool insert speed 90 mm/s and preheating time 5 s. © 2013 The Japan Institute of Light Metals.