旋转摩擦挤压加工对不同时效态6061铝合金显微组织和力学性能的影响

Effect of rotational friction extrusion on microstructure and mechanical properties of 6061 aluminum alloys with different aging states

采用旋转摩擦挤压(rotational friction extrusion,RFE)工艺对不同时效态6061铝合金进行加工,研究RFE对不同时效态6061铝合金显微组织和力学性能的影响。结果表明:RFE能够破碎6061铝合金中的难熔AlFeMnSi相,导致合金中的AlFeMnSi相细小且分布均匀。预析出粗大Mg2Si相在RFE加工过程中摩擦热和变形作用下,回溶后重新析出,致使预析出粗大Mg2Si相对材料动态再结晶中的粒子激发形核(particle stimulated nucleation,PSN)机制无影响,RFE加工后的晶粒尺寸变化较小。RFE使淬火态6061铝合金强度下降,但长时间时效态6061铝合金经RFE加工后强度得到提升。然而,RFE加工的材料内部存在孔洞,合金断后伸长率降低。

6061 aluminum alloys with different aging states were prepared by rotational friction extrusion(RFE).The effect of RFE on the microstructure and mechanical properties of 6061 aluminum alloys with different aging states was investigated.The results show that the refractory AlFeMnSi phase of 6061 aluminum alloys can be broken by using RFE,resulting in the fine and uniform distribution of the AlFeMnSi phase in the alloy.Under the combined effects of frictional heat and deformation during RFE processing,the pre-precipitated coarse Mg2Si phase is dissolved and re-precipitated,resulting in that the pre-precipitated coarse Mg2Si phase has no effect on the particle stimulated nucleation(PSN)mechanism in the dynamic recrystallization of the material.Therefore,the size of grain exhibits negligible change by RFE.RFE reduces the strength of as-quenched 6061 aluminum alloys,while the strength of 6061 aluminum alloys with a long-term aging state can be increased by RFE.However,there are holes inside the material processed by RFE,which reduce the elongation of the alloys.