Effect of Heat Treatment Conditions and Cryogenic Treatment on Microhardness and Tensile Properties of AZ31B Alloy

The effect of heat treatment and cryogenic treatment on the microstructure, tensile properties, and microhardness of the rolled (R) AZ31B magnesium alloy was investigated. AZ31B alloy was heated, shallow and deep cryogenically treated (DT) at 150, 250, 350, − 82, and − 190 °C for 1, 15, and 72 h. The superior microhardness, yield, and tensile strength were obtained for DT AZ31B alloy. The grain refinement, Mg 17 Al 12 precipitation formation, and better peak intensity ratio was noted for DT specimen. The heat treatment temperature of 250 °C-1 h (HT2) enhanced the elongation of AZ31B alloy. The fracture mode of the R specimen was completely dominated by both ductile and brittle fractures. The tensile fracture present in the DT specimen was a ductile fracture, which was characterized by the formation of fine dimples and fewer cleavage facets. The heat and cryogenic treatments enhanced the microhardness and tensile properties of the rolled AZ31B Mg alloy.