不同板厚AZ31B镁合金CMT焊接接头性能对比试验

Comparative test of properties of AZ31B magnesium alloy CMT welded joints with different plate thicknesses

使用CMT焊接方法对3mm、6mm两种厚度的AZ31B镁合金进行焊接试验,并对焊缝进行了焊缝形貌、微观结构、显微硬度、断口及疲劳性能等方面的试验分析。结果表明:合理的焊接参数能得到优化的焊缝,且金相组织与板厚无关。3mm厚的AZ31B镁合金可达到母材抗拉强度的83%,6mm厚的AZ31B镁合金可达到母材抗拉强度的88.7%,说明AZ31B镁合金CMT焊接接头的脆性随着板厚增加而增大,同时接头的显微硬度整体呈W形分布,焊缝区显微硬度高于热影响区且薄板热影响区硬度略高于厚板。在进行了200万次循环后,接头的疲劳强度为16.72MPa,仅为其抗拉强度的7.8%,焊接接头的疲劳强度远低于其抗拉强度。接头拉伸断裂位置位于母材,呈45°角切断,断裂位置与显微硬度最低位置相吻合,接头的断裂区域有明显的塑性变形痕迹。

Welding tests were carried out on AZ31B magnesium alloy of two thicknesses(3mm and 6mm)using the CMT welding method,and the obtained welds were tested and analyzed in terms of appearance and morphology,microstructure,micro hardness,fracture and fatigue properties.The results show that:reasonable welding parameters can get optimized weld seam,and the metallographic organization is independent of the plate thickness.3mm thick AZ31B magnesium alloy can reach 83%of the tensile strength of the base material,and 6mm thick AZ31B magnesium alloy can reach 88.7%of the tensile strength of the base material,which indicates that the brittleness of AZ31B magnesium alloy CMT welded joints increases with the thickness of the plate,and at the same time,the micro hardness of joints is overall in the form of W-shape.At the same time,the overall micro hardness of the joint is W-shaped distribution,the micro hardness of the weld core area is higher than the heat-affected zone and the hardness of the heat-affected zone of the thin plate is slightly higher than the thick plate.The fatigue strength of the joint under 2×10^(6) cycles is 16.72MPa,which is only 7.8%of its tensile strength,and the fatigue strength of the welded joint is much lower than their tensile strength.The tensile fracture location of the joint is located in the base material,cut off at an angle of 45°,the fracture location coincides with the lowest microhardness location,the fracture region of the joint has obvious traces of plastic deformation.