摘要
采用TIG焊对5 mm厚AZ31B挤压镁合金板材进行了焊接试验。采用万能拉伸试验机、金相显微镜、扫描电子显微镜和显微硬度仪等分析测试手段对焊接接头的组织、力学性能以及断口形貌等进行了分析。探讨了焊接电流对焊接接头的组织及力学性能的影响,揭示了不同焊接电流下焊接接头的断裂机制。结果表明,采用TIG焊焊接5 mm厚AZ31B镁合金板时,开X型坡口,采用双面焊接双面成型工艺,在130~145 A焊接电流及合适焊接速度条件下,能得到表面成型良好的焊接接头。当正反面焊接电流均为145 A时,AZ31B镁合金板焊接接头的抗拉强度达到最大值248.6 MPa,约为母材强度的84.0%。AZ31B镁合金板焊缝区显微硬度比母材区稍有所下降,热影响区显微硬度下降比较严重。当焊接电流为145 A时,AZ31B镁合金板焊接拉伸断口有大量韧窝,属韧性断裂。
TIG welding test of AZ31B magnesium alloy plates with the thickness of 5 mm was carried out.The microstructures,tensile fracture surfaces,and mechanical properties of welded joints were investigated by means of an optical microscope,a scanning electron microscopy,a universal tensile testing machine and a microhardness testing instrument.The effects of the welding current on the microstructure and mechanical properties of welded joints were discussed.The results show that when TIG welding was used to weld AZ31B magnesium alloy plates with the thickness of 5 mm,the welded joints with a smooth weld surface can be obtained at the welding current range from 130 to 145 A.When the welding current is 145 A,the maximum tensile strength of the welded joints is 248.6 MPa,approximately 84.0% of the strength of the base material.The microhardnesses of the weld zone(WZ) and the heat affected zone(HAZ) of AZ31B magnesium alloy plates are reduced,and the microhardness in HAZ is the lowest.When the welding current is 145 A,there are a large number of dimples on the tensile fracture surface of welded joint,and this fracture belongs to the tough fracture.
出处
《吉林大学学报（工学版）》
EI
CAS
CSCD
北大核心
2009年第S1期159-163,共5页
Journal of Jilin University:Engineering and Technology Edition
基金
教育部新世纪优秀人才支持计划项目
长春市科技支撑计划项目(2007KZ07)
