论文部分内容阅读
对比研究了AZ31B镁合金空气环境搅拌摩擦焊接(Friction Stir Welding,FSW)和水环境搅拌摩擦焊接(Submerged Friction Stir Welding,SFSW)接头的微观组织与力学性能。结果表明:SFSW接头焊核区为细小等轴状再结晶晶粒。随着焊接速度的增大,焊核区晶粒尺寸增大,显微硬度值降低。FSW接头表层处的显微组织比中心处粗大,且分布不均匀;而SFSW接头表层处的显微组织比中心处明显细小。FSW接头的表层硬度值低于中心处的硬度;而SFSW接头的表层硬度值高于中心处的硬度。当旋转速度为950r·min-1、焊接速度为75mm·min-1时,SFSW接头的抗拉强度值达到最大,为母材强度的72%,拉伸断口表现为解理断裂特征。
The microstructures and mechanical properties of AZ31B magnesium alloy were compared between Friction Stir Welding (FSW) and Submerged Friction Stir Welding (SFSW). The results show that the weld zone of the SFSW joint is a fine equiaxed recrystallized grain. With the increase of welding speed, the grain size of the nugget nucleus increases and the microhardness decreases. The microstructure at the surface of the FSW joint is thicker and unevenly distributed than the center, while the microstructure at the surface of the FSW joint is obviously smaller than the center. The FSW joint has a lower surface hardness than the center and the SFSW joint has a higher surface hardness than the center. When the rotation speed is 950r · min-1 and the welding speed is 75mm · min-1, the tensile strength value of SFSW joint reaches the maximum, which is 72% of the base metal strength. The tensile fracture shows the characteristics of cleavage fracture.