6005A-T6铝合金MIG焊接接头疲劳性能及小裂纹扩展机制

Fatigue Property and Small Crack Propagation Mechanism of MIG Welding Joint of 6005A-T6 Aluminum Alloy.

作者信息

Peng Zeng, Yang Shanglei, Wang Zhentao, Gao Zihao

机构信息

School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620, China.

Shanghai Laser Intelligent Manufacturing and Quality Inspection Professional Technical Service Platform, Shanghai 201620, China.

出版信息

Materials (Basel). 2022 Jul 4;15(13):4698. doi: 10.3390/ma15134698.

DOI:10.3390/ma15134698

PMID:35806822

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC9267679/

Abstract

In this study, metal inert gas welding (MIG) was applied to 4 mm thick 6005A-T6 aluminum alloy welding. Compared with other parts, the hardness of the weld zone (WZ) was the lowest, about 67 HV. There was the Softening in WZ, which might make WZ the weakest zone. Then, fatigue tests were carried out on MIG welded joints. All the fatigue specimens fractured at the weld toe of the lap joint, and the fracture was characterized by a cleavage fracture. Crack closure induced by oxide was observed during the steady propagation of the fatigue crack. Impurities hindered crack propagation, changed the direction of crack propagation, and appeared in stepped fatigue strip distribution morphology; in the process of the main crack propagation, the initiation and propagation of small cracks were easily restricted and hindered by the main crack, which slowed down the propagation rate and even stopped the propagation directly.

摘要

在本研究中，采用熔化极惰性气体保护焊（MIG）对4mm厚的6005A-T6铝合金进行焊接。与其他部位相比，焊缝区（WZ）的硬度最低，约为67 HV。焊缝区存在软化现象，这可能使焊缝区成为最薄弱的区域。然后，对MIG焊接接头进行疲劳试验。所有疲劳试样均在搭接接头的焊趾处断裂，断口特征为解理断裂。在疲劳裂纹稳定扩展过程中观察到氧化物引起的裂纹闭合。杂质阻碍裂纹扩展，改变裂纹扩展方向，并呈现出阶梯状疲劳条带分布形态；在主裂纹扩展过程中，小裂纹的萌生和扩展容易受到主裂纹的限制和阻碍，从而减缓扩展速率甚至直接停止扩展。