搅拌摩擦焊搅拌器头形状对2060Al-Li合金焊缝组织和性能的影响

Effect of Shapes of Stirrer Head for Friction Stir Welding on Microstructure and Properties of 2060Al-Li Alloy Welding Seam

采用三种不同形状的搅拌器头以不同的搅拌器转速和焊接速度对厚度为2 mm的2060Al-Li合金试板进行了搅拌摩擦焊接。随后检测了焊接接头焊缝的微观组织和宏观形貌以及力学性能和疲劳性能。结果表明:采用双圆环形搅拌器头以较低搅拌器转速和较高焊接速度焊接的接头变形较小,力学性能较好,其断后伸长率为9.4%,强度达到母材的83%;采用双圆环形搅拌器头以600 r/min的搅拌器转速和400 mm/min焊接速度焊接的接头焊核区组织均匀细小,焊核区上、下部的组织比中部更细小;前进侧和后退侧的热机影响区均发生了一定量的变形,热影响区组织比焊核区和母材明显粗大;以250 MPa最大应力测定的接头的平均疲劳寿命为44.338万次。

2-mm-thick 2060Al-Li alloy test plates were friction stir welded by three different shapes of stirrer heads at different stirrer rotating speeds and different welding speeds.After this,the welded joints were tested for microstructure and macroscopic appearance of the weld,as well as mechanical properties and fatigue property.The results showed that(a)the joint welded by a double-ring-shaped stirrer head at a lower stirrer rotating speed and a higher welding speed exhibited less deformation and better mechanical properties,elongation being 9.4%and strength being up to 83%of the base material;(b)the joint welded by a double-ring-shaped stirrer head at stirrer rotating speed of 600 r/min and welding speed of 400 mm/min had uniform and fine structure in weld nugget area,and the structures of upper and lower parts were finer than that of middle part in the weld nugget area;(c)the forward and the backward sides of the thermo-mechanically affected zone all exhibited a certain amount of deformation,and the structure in heat affected zone was significantly coarser than the those of the weld nugget area and the base material;and(d)average fatigue life of the welded joints tested at a maximum stress of 250 MPa was 443380000 times.