Al-Mg-Si铝合金6061焊接接头组织软化与强化机理

Soften and Strengthen Mechanism of Welded Joints of Al-Mg-Si 6061 Alloy

通过拉伸、硬度试验以及金相分析,对铝合金6061焊接接头的软化和强化机理进行了研究。结果表明：热处理前焊接接头强度为175 MPa,经（525±5）℃×2 h固溶＋（165~175）℃×8 h时效热处理后,焊接接头强度提高至236MPa,HAZ的硬度得到明显改善,拉伸试验断裂位置由HAZ转至焊缝,固溶＋时效热处理使得焊缝区和HAZ析出大量弥散与基体共格的强化相,使焊接接头的强度、硬度显著提高。

The soften and strengthen of aluminum alloy 6061 welded joints were investigated by tensile test,hardness test and metallographic analysis.The results show that the strength of welded joint without heat treatment is 175 MPa,after solid solution（525 ± 5） ℃× 2 h and ageing treatment（165~175）℃× 8 h.The strength of welded joint reaches 236 MPa,and the hardness of HAZ is also greatly improved.The failure position of tensile samples without heat treatment is at the HAZ,while the counterpart after solid solution and ageing treatment turns into welded seam,and a great deal of strength phase,which coherent with base metal,precipitate and distribute uniformly in the welded seam and HAZ,which lead to obvious improvement of tensile strength,hardness of welded joint.