Improvement of formability of AZ31 magnesium alloy by repeated roll bending process

摘要

Dispersion of the basal texture is effective to improve the formability. A repeated roll bending process (7 work rolls, work roll radius of 32 mm, roll pitch of 40 mm) was applied to AZ31 magnesium alloy sheets by activating the tensile twins. The larger applied bending strain per pass was effective to increase hardness at the surface of the sheet. The Erichsen value was slightly increased from 3.0 to 3.5 mm by subjected 2 passes repeated roll bending and subsequent at 180 °C for 12 hours annealing without decreasing the hardness of the sheet before bending (Hv=60). The Erichsen value of 3.3 and over hardness of Hv 65 through thickness were obtained by 2 passes bending and 160°C for 12 hours annealing. The tensile twins and texture randomizing were observed around center of thickness by electron backscatter diffraction (EBSD) analysis. It was possible to increase formability of AZ31 magnesium alloy by the repeated roll bending and subsequent low temperature annealing.