7075与ER5356铝合金焊丝用于7075铝合金MIG焊接头性能对比研究

7075 and ER5356 aluminum alloy wire for MIG welding of 7075 aluminum alloy Comparative study of joint performance

采用MIG焊的方式使用自制7075铝合金焊丝与市面购进的ER5356焊丝进行3mm厚7075铝合金对接焊,对比分析两种焊丝焊接接头的显微组织与力学性能。经过光学显微镜(OM)、X射线衍射(XRD)、扫描电镜(SEM)与能谱仪(EDS)结合室温拉伸与显微硬度测试,结果表明:两种接头焊缝组织均为枝晶网状组织,但由于合金元素含量与热导量增大,7075接头焊缝组织相对细小且枝晶特征更为明显。SEM和XRD检测分析得出,由于焊接时金属流动作用将部分母材合金元素带至焊缝,两者焊缝析出相均主要为η相(MgZn_(2))、S相(CuMgAl_(2))或T相(AlZnMgCu),同时存在Al_(13)Fe_(4)金属化合物。7075焊缝平均硬度为120HV,相较于5356焊缝更为优异;两者拉伸力学性能较为接近,断裂机制相同。

Using the method of MIG welding,the self-made 7075 aluminum alloy welding wire and the commercially available ER5356 welding wire were used for 3mm thick 7075 aluminum alloy butt welding.The microstructure and mechanical properties of the welded joints of the two welding wires were compared and analyzed.Through optical microscope(OM),X-ray diffraction(XRD),scanning electron microscope(SEM) and energy dispersive spectrometer(EDS)combined with room temperature tensile and microhardness test results,the results show that the weld structure of both joints is dendritic network However,due to the increase of alloying element content and thermal conductivity,the weld microstructure of 7075 joint is relatively fine and the dendrite characteristics are more obvious.SEM and XRD analysis showed that due to the metal flow during welding,part of the base metal alloy elements were brought to the weld,and the precipitation phases of the two welds were mainly η phase(MgZn_2),S phase(CuMgAl_2) or T phase(AlZnMgCu),with the presence of Al_(13)Fe_(4) metal compounds.The average hardness of the 7075 weld is 120HV,which is better than that of the 5356weld;the tensile mechanical properties of the two are similar,and the fracture mechanism is the same.