摘要
The microstructure and mechanical properties of multi-layer multi-pass TIG welded joints of Al-Zn-Mg alloy plates were studied.The phase constituent and microstructure of different regions of the welded joints were characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),transmission electron microscopy(TEM)and energy disperse spectrum(EDS),while the mechanical properties were evaluated according to the impact test.A dispersively distributed spherical and needle-likeη(MgZn2)phase was obtained in the welding seam.The phase composition of the heat-affected zone(HAZ)wasα(Al)+η(MgZn2)+Al6Mn,and there were a large number of dispersively precipitated nanoscale particles.The welded joint zone had the highest impact toughness as compared with the other parts of the joint.The MgZn2 phase in the weld zone contributed to the improved toughness of the joint.Al2 MgCu phase in HAZ was proven to act as a crack source during fracture.
研究Al-Zn-Mg合金厚板多层多道TIG焊接接头的显微组织和冲击力学性能。通过扫描电子显微镜(SEM)、X射线衍射(XRD)、透射电子显微镜(TEM)和能量色散谱(EDS)对焊接接头不同区域的相组成和显微组织进行表征,同时对其进行冲击力学性能测试。结果表明:焊缝中产生弥散分布的球状和针状η(MgZn2)相。焊接热影响区的物相组成为α(Al)+η(MgZn2)+Al6Mn,并存在大量弥散分布的纳米级沉淀颗粒。焊接接头焊缝区冲击韧度最高,焊接接头焊缝区中的MgZn2相有利于接头韧性的提高。焊接热影响区中Al2MgCu相在断裂过程中起到裂纹源的作用。
基金
Project(ZR2016EEQ03) supported by the Shandong Province Natural Science Foundation,China
Project(2018M641822) supported by the China Postdoctoral Science Foundation-General Program
Project(HIT.NSRIF.201703) supported by the Natural Scientific Research Innovation Foundation in HIT,China
