초기 집합조직과 변형조건에 따른 AZ91 마그네슘 합금의 고온 변형 중 집합조직 형성거동

Abstract

Magnesium alloys were limited by poor formability at room temperature which was caused by the limited number of slip systems. The texture control plays an important role in plastic workability of magnesium. Many studies have been conducted in order to understand the texture evolution in magnesium alloys. Two authors report the characteristics of texture formation deformation became clear with an increase of solute content during high-temperature deformation in Al-Mg alloys. Therefore, it is expected that the similar characteristic appears in AZ magnesium alloys with the solute and solvent element replacement relationship at high temperature deformation. Also, in previous study, the formation behavior of texture and microstructure in AZ80 magnesium alloy under high temperature deformation was investigated. It was found that the basal texture was formed at stress of more than 15-20MPa and the non-basal texture was formed at stress of less than 15-20MPa. This means that stress of 15-20MPa is the change point of deformation mechanism. This study, AZ91 magnesium alloy with 9% aluminum concentration was experimentally investigated by uniaxial compression test. Uniaxial compression is conducted at 723K with a strain rates of 0.0005s-1 to 0.05s-1. Texture measurement was carried out on the compression planes by the Schulz reflection method using nickel filtered CuKα radiation. EBSD measurement was also conducted in order to observe spatial distribution of orientation. As a result of uniaxial compression deformation, the maximum value of the flow stress is observed in all the cases at the true stress – true strain curve for three type of specimens. Also, on texture measurement, it was found that the main component of texture and the accumulation of pole density vary depending on deformation condition. A crystal orientation component after deformation is formed by continuous formation behaviors.