锥形光头搅拌针搅拌摩擦焊接铝锂合金接头组织及力学性能

采用锥形光头搅拌针搅拌摩擦焊接5mm厚铝锂合金轧制板材，并对接头微观组织、力学性能及断裂特性进行了深入研究。结果表明，接头由焊核区、热机影响区和热影响区构成。焊核区在焊接过程中发生动态再结晶，形成细小的等轴晶晶粒，晶界处分布有大量的偏析相，热影响区组织发生粗化，形成粗大的板条状组织，前进侧热机影响区组织发生回复反应，后退侧热机影响区发生回复 再结晶反应；硬度测试结果表明，接头发生软化，后退侧材料的软化区间和软化程度均高于前进侧；断口实验结果表明，接头断裂模式为解理断裂。

Microstructures and Mechanical Properties of Al-Li Alloy Friction Stir Welds with a Cone-shape and Non-whorl Pin

Friction stir welds (FSW) in 5mm thick, Al-Li alloy rolled sheet material have been completed. Metallurgical, hardness, tensile strength and fracture measurements have been performed. Metallurgical measurements show that there exist three different zones in FSW joints: weld nugget zone (WNZ), heat affected zone (HAZ) and thermal-mechanically affected zone (TMAZ). During welding, microstructures in WNZ occurred dynamic recrystallization and generated fine equiaxed grains, at which boundary lots of segregation microstructures appeared; microstructures in HAZ were coarsed; microstructures in advancing-side TMAZ occurred recovery; and microstructures in retreating-side TMAZ occurred recovery and recrystallization. Hardness measurements confirmed that joint was softened, and the softened degree and zone of retreating-side material was higher and wider than that of advancing-side material respectively . Fracture measurements show that the mode attributed to cleavage fracture.