ZL114A铸铝搅拌摩擦焊接头性能

研究了采用不同焊接参数时ZL114A铸铝搅拌摩擦焊接头的金相组织、硬度分布及力学性能。结果表明，ZL114A铸铝的搅拌摩擦焊焊接性良好。焊核区的微观组织是无方向性的、细小的等轴晶粒。细化的硅粒子均匀布满整个焊核区。与粗大的树枝状母材相比，焊核晶粒细小、均匀而致密，没有观察到气孔等缺陷。焊缝区硬度分布较母材稳定，变化范围小。随着焊速增加，硅粒子所占体积比逐渐下降。热一机械影响区晶粒被拉长。接头的力学性能与焊接参数的匹配有关系。采用高焊速及转速与焊速比在3左右，获得的接头抗拉强度可达到母材的91％。焊后经T6热处理，可与同炉热处理母材等强。

FRICTION STIR WELDED JOINT PROPERTIES OF CAST ALUMINUM ALLOY

The weld characteristics of ZL114A cast aluminum alloy by friction stir welding, such as the microstructures, the hardness distribution and mechanical properties, have been introduces in this paper. As the result of this study, the FSW weld-ability of ZL114A cast aluminum alloy is sound, The microstructures of the joint are composed of weld nugget, thermo-mechanical affected zone (TMAZ), heat affected zone (HAZ), and base metal(BM).Comparing with the coarse dendrite microstructures of TMAZ and BM, the NZ(nugget zone) of ZL114A gets a very fine recrystallized equal-axial grain microstructure without visual defects. The eutectic Si particles are homogeneously dispersed in NZ and become even finer with high welding parameters. The hardness distribution of joint is consistent and less fluctuation. Mechanical properties of the friction stir welded joint are associated with the welding parameters. Under the optimized condition, when the ratio of rotate speed and welding speed approaches to 3, the tensile strength of the ZL114A joints can attain 91% that of the BM. After the post-weld T6 heat treatment , the tensile strength of the joints is equal to the BM.