GTAW焊接AZ31B镁合金管状T型接头微观组织和硬度分析

Microstructure and Hardness Analysis of GTAW Welded AZ31B Alloy Tubular T Shaped Joint

采用光学金相显微镜研究了GTAW焊接AZ31B镁合金管状T型接头的微观组织和缺陷,采用V-1000型维氏硬度计检测了焊缝横截面的显微硬度分布。结果表明,焊缝存在的主要缺陷为气孔,气体来源于母材表面吸附水分中的H元素;焊接接头不同区域的晶粒尺寸是决定其微观硬度值的主要因素,不同区域晶粒尺寸排列大小为热影响区(HAZ)>母材(BM)>焊缝区(WZ),对应的显微硬度大小排列顺序为WZ>BM>HAZ。

The microstructure and defects of GTAW welded AZ31B alloy tubular T shaped joint was studied by optical metallographic microscope （OM）. The microhardness distribution of weld cross-section was studied by vickers hardness tester. The results show that the main defect existing in the weld joint is porosity, the gas is from the H element adsorbing in water on the surface of parent metal. The grain size in different areas of the welded joint is the main factor for determining the micro hardness. The array size of the grain size for different regions is heat affected zone （HAZ） 〉 mother materials （BM） 〉 weld zone （WZ）. The corresponding order of the microhardness is WZ 〉 BM 〉 HAZ.