Effect of FSP parameters on microstructure evolution and mechanical properties of AZ31 magnesium alloy

Abstract

To investigate the microstructure evolution and mechanical properties of materials treated by friction stir processing process at various the shoulder sizes and rotating speeds of the tool, a series of friction stir processing experiments were carried out on the AZ31 magnesium alloy with thickness of 4mm by using tool shoulder sizes of 12, 16 and 18mm, and two kinds of rotating speeds of 750r/min and 1500r/min with a constant feed speed of 60mm/min were supplied. Based on the analysis of morphology and mechanical properties of the materials, results demonstrated that reduction of tool shoulder size and rotating speed would contribute to more remarkable the grain refinement effect and affect the strong texture and extreme density strength of the material, leading to higher microhardness. However, lower mechanical properties of yield strength and tensile strength were obtained at these parameters owing to the existence of internal organization defect and stronger defect sensitivity of it. All of the findings would further deepen the understanding of the technique of friction stir processing and contribute to the application of AZ31 magnesium alloy treated by friction stir processing.