A Study of Friction Stir Welding on the Joining Properties of Magnesium Alloy AZ31B-H24

[[abstract]]Due to their lightweight, high specific stiffness and specific strength, magnesium alloys have been widely used for 3C (Computer, Communication and Consumer Electronics) industries and vehicles recently. Friction stir welding (FSW) is an emerging solid-state and nonpolluting joining process that produces low-distortion and low-cost welds. This study focus on 3-mm AZ31B-H24 plate by FSW, using the tool self-designed and self-made, with cramp fixture located and fixed, proceeding various parameter combination, including stir rod travel angle, tool rotation, traverse speeds and plunge depth. Through temperature record of thermocouples, distribution of temperature analysis executed by ANSYS software, obtain approximating function estimate temperature. Microstructures of the welds will be examined using optical microscopy (OM) and scanning electron microscopy (SEM). Tensile properties and micro hardness of the welds will be evaluated at room temperature. According to the experimental results, the weldable parameters for AZ31B-H24 plates by FSW are quite board, but modifying parameters have different mechanical property. With travel angle 2?and leading depth 0.08 mm, when FSW welding parameters between 2 to 10, obtain about 230 ℃ to 290 ℃ heat input, and the internal weld pass defect-free, fine equiaxial grain formed in stir zone, and break in boundary between stir zone and HAZ. The efficiency of joint is about 78.75% to 87.11%. Especially when approaching 5.6 with proper revolution pitch, advancing side and retreating side of weld pass have uniform frictional heating, the tensile strength is highest.