铸造镁合金中微孔对其组织和力学性能的影响

Origination and Elimination of Micro-porosity in Cast Mg Alloy

利用镁液定量测氢方法和定量金相技术,研究了镁合金中含氢量、试样厚度和除气方式对微孔的影响。结果表明,熔剂保护下熔炼的镁液含氢量比气体保护下的要高,相应的微孔也多;同一含氢量下随铸件厚度增加,微孔增多;在熔剂保护下Ar气除气后铸件微孔明显减少。力学性能试验表明,镁液在熔剂保护下熔炼并利用Ar气除气,铸件抗拉强度比不除气时提高了21%,伸长率提高了50%。

Effects of hydrogen content in liquid magnesium,sample thickness and degassing ways on micro-porosity in magnesium alloy have been investigated by quantitative hydrogen-measuring and quantitative metalography methods.The results show that micro-porosity in the magnesium alloy in the condition of the flux covering is more than that of the ones in the condition of inertial gas protection.With increasing in parts thickness,the micro-porosity in the magnesium alloy parts is increased with the same hydrogen content.Micro-porosity in the magnesium alloy can be reduced remarkably after Ar-degassing with flux protection,which obviously improves the tensile strength by 25% and the elongation by 50% compared with the parts without Ar-degassing treatment.