AZ31 마그네슘 합금의 가공량 및 열처리 조건이 진동 감쇠능과 미세조직에 미치는 영향

Abstract

Pure magnesium and its alloys are well-known to having high damping capacity. However, damping capacity of magnesium is significantly reduced, if magnesium is alloyed in order to improve its mechanical properties. Many researchers have consistently studied for texture control and grain refinement in order to improve room temperature formability, however, the study on specific properties of magnesium is still insufficient. It was found that damping capacity has been affected by grain size and initial texture. In this study, change of damping capacity on other temperature condition has been investigated in order to clarify preferred factor. The crystal orientation, residual dislocation density, grain size, and degree of recrystallization has been considered as contributed factor on damping capacity. AZ31 Magnesium alloy was rolled at 673K with rolling reduction of 10% and 50%, respectively. Damping capacity test specimens were machined out from rolled plate with parallel to the Normal plane. These specimens were annealed at various heat treatment conditions. Then, damping capacity was measured by using internal friction measurement machine, and microstructure was examined by using optical microscopy. Texture measurement including of XRD and EBSD was carried out on damping specimens in order to analyze crystal orientation distribution. As a result in this study, with increasing of heat treatment temperature, damping capacity of 50% rolled specimen rapidly increased than that of 10% rolled specimen. At the beginning of the heat treatment, damping capacity was affected by residual twin fraction, however after tensile twin was disappeared, damping capacity was affected by degree of recrystallization and residual dislocation density.