重复补焊和热处理对低压铸造ZL104合金力学性能和组织的影响

通过金相显微镜(OM)、能谱分析(EDS)、拉伸试验和硬度测试等方法对低压铸造ZL104合金经过重复热处理和多次补焊的显微组织和力学性能进行研究。结果表明,经过1次、2次、3次补焊和热处理后,合金抗拉强度分别下降了8.4%、13.1%、20.3%,伸长率分别下降了14.1%、34.3%、52.1%。随着补焊和热处理次数增加,补焊区域硬度下降明显,母材硬度变化不大。研究发现,随着焊接次数增加,Mg严重烧损,导致Mg2Si强化相减少,铸态组织多为枝晶组织,焊接后形成细小气孔,最终导致合金焊接区力学性能降低。

Influence of Reheat Treatment and Multi-welding Repairing on Mechanical Properties and Microstructure of the Zl104Alloy by Counter-Gravity Casting

The mechanical properties and microstructure of ZL104 alloy by reheat treatment and multi-welding repair were investigated by tensile,hardness testing and OM,EDS.The results show that the tensile strength is decreased by 8.4%、13.1%、20.3% and the elongation is decreased by 14.1%、34.3%、52.1% with one,twice and three welding repair after heat treatment.The hardness of welding zone is decreased remarkably and the base metal hardness is changed slightly.The welding repair times can result in the Mg element burn-loss,so the strengthening phase Mg2 Si is reduced and the welding microporosity is generated in form of the dendritic as-cast structure,resulting in the decrease of mechanical properties of the welding zone.