AZ31 镁合金板材自阻加热超塑成形及电流宏微观作用分析

目的为提高镁合金板材超塑成形加热过程的效率,将自阻加热引入到超塑成形过程中。方法通过自阻加热实验,分析了电流密度对坯料温度及升温速率的影响;设计了自阻加热胀形装置并确定了工艺参数,实现了AZ31镁合金的自阻加热超塑胀形。结果采用该加热方式可将坯料加热时间从数十分钟缩短至几十秒,极大地提高了加热速率,降低了能耗。结论分析了在电流作用下镁合金的变形机制,发现电流可以通过促进材料的再结晶形核、位错滑移来提高材料塑性,并具有钝化和阻碍空洞扩展的作用。

Resistance Heating Superplastic Forming of AZ31 Magnesium Alloy and Macro and Microcosmic Function of Current

Objective In order to save energy and improve efficiency, the current is adopted in superplastic forming process. Methods Through resistance heating experiments, the influence of current density on temperature of sheet and heating rate is analyzed. By the design of the forming apparatus and determination of the technology parameters, the resist-ance heating forming is realized. Rsults The results show that, resistance heating can reduce heat-up time from dozens of minutes to dozens of seconds, which greatly improves the heating efficiency and reduces energy consumption. Conclusion The deformation mechanism with the action of current is discussed. It is found that the current can promote recrystallization-nu-cleation and dislocations slipping and hinder the growth and join of cavities, that all improve the plastic property of material.