Springback characteristics of magnesium alloy sheet AZ31B in draw-bending

Abstract

In this study, we carried out a two-dimensional draw-bending test on an AZ31B magnesium alloy sheet at various forming temperatures and blank holding forces, and the springback characteristics of the Mg alloy sheet were systematically examined. The amount of springback decreased with increasing temperature and blank holding force. The decrease in the amount of springback caused by the increase in temperature was much larger than that caused by the increase in blank holding force, which indicated that increasing temperature was much more effective for decreasing the amount of springback than increasing blank holding force. The amount of springback became negligible at 200°C and above. This result was attributable to the following factors: (a) flow stress decreased rapidly as temperature increased, (b) reverse bending on me sidewall arose at 150°C and above, and (c) fine grains due to dynamic recrystallization were formed at 200°C and above. Microstructure evolution during the draw-bending test was also observed with particular focus on twinning, and its effects on springback characteristics were studied in detail. © 2010 The Japan Society for Technology of Plasticity.