镁合金板材正反向快速气压胀形实验

Experimental study on direct-reverse quick gas blow forming of magnesium alloy sheet

采用两种不同轮廓的反向预成形模具进行高应变速率气压胀形实验,结果表明,内外凹圆弧预成形模的成形效果好于半圆弧预成形模,反向胀形的时间可控制在10s,表面和微观组织均无明显缺陷。利用上述预成形模进行半球件正反向气压自由胀形实验,研究正反向胀形的效果,正反向胀形可以显著提高AZ31B镁合金板料的成形能力,使胀形件高径比从0.344提高到0.522,并使壁厚均匀度从19.4%提高到半圆弧预成形模具的32.3%,内外凹圆弧预成形模具的45.5%。在400℃温度下胀形300s,可以成形出高径比为0.522的完好半球件。

High strain rate gas blow forming tests were performed using two types of reverse preform dies,and the results showed that the forming effect of inner and outer circle arc preform die was better than that of semicircle preform die.The surface and microstructure of formed parts appeared hardly defect and the reverse forming time was shortened to 10s.Direct-reverse free bulging tests for hemisphere part with the above perform dies were conducted to investigate the direct-reverse forming behaviour.Compared to unidirectional free bulging,the direct-reverse forming improved significantly formability of AZ31 magnesium alloy sheet,and increased the height to diameter ratio of hemisphere part from 0.344 to 0.522 and the uniformity of thickness distribution from 19.4% to 32.3% for semicircle perform die and even to 45.5% for inner and outer concave circle arc perform die.The undamaged hemisphere part with height to diameter ratio of 0.522 was formed successfully at 400℃ within 300s.