Microstructure, texture and mechanical behavior characterization of hot forged cast ZK60 magnesium alloy

Abstract

Uniaxial tension and compression tests were conducted to investigate the quasi-static performance of ZK60 Mg alloy in cast, followed by forging at optimum temperature of 450°C and a ram speed of 39mmmin-1. Microstructure and texture analysis showed that the as-cast alloy exhibited a dendritic structure with casting porosity and random texture. In contrast, the forged alloy exhibited a refined grain structure with a significant reduction in casting porosity, while the texture changed to sharp basal texture. Measured mechanical properties of the forged alloy showed that strength did not change, however, ductility improved by 75%. The analysis of the fracture surface of the forged alloy under tension revealed a ductile fracture with dimple morphology, while the as-cast alloy displayed a brittle fracture with open pores. This demonstrated that the reduction of casting defects and dendritic morphology, as well as the evolution of recrystallized grains, enhanced ductility, while partial dynamic recrystallization through the forging process resulted in only marginal modification of strength in the forged condition.