7050铝合金搅拌摩擦焊接头的微观织构演变与力学性能

Microtexture Evolution and Mechanical Properties of Friction Stir Welded 7050 Aluminum Alloy

对5 mm厚的7050铝合金搅拌摩擦焊接头各区域的微观织构演变、硬度分布及拉伸性能进行了研究,并与完整焊缝接头的拉伸性能进行了对比。结果表明:母材主要为亚结构组织,存在(011)[100]高斯织构、(112)[111]铜织构和(001)[100]立方织构;焊核区发生动态再结晶,主要为[100]∥WD、[110]∥WD、[111]∥WD丝织构;前进侧热力影响区存在(111)[110]剪切织构、(110)[112]黄铜织构、(100)[012]和(100)[012]再结晶织构;而后退侧热力影响区为(001)[110]旋转立方再结晶织构和(112)[111]铜织构,主要是由各微区热-力作用不同导致。焊缝区硬度呈“W”型分布,硬度最小值出现在后退侧热影响区。前进侧与后退侧抗拉强度分别为496.9 MPa和505.2 MPa,达到母材强度的88%和90%;焊核区抗拉强度为440.4 MPa;完整焊缝抗拉强度最低,为415.7 MPa。

The microtexture evolution,hardness distribution and tensile properties of the friction stir welded joint of 7050 aluminum alloy with a thickness of 5 mm were studied and compared with the tensile properties of the complete welded joints.The results show that the base metal is mainly for the substructure,with(011)[100]Goss texture,(112)[111]copper texture and(001)[100]Cube texture.Dynamic recrystallization occurred in the weld nugget zone,mainly existing in[100]∥WD,[110]∥WD,[111]∥WD fiber texture.There are(111)[110]shear texture,(110)[112]brass texture,(100)[012]and(100)[012]recrystallization texture in the thermos-mechanically affected zone of advancing side;the thermo-mechanically affected zone of retreating side is(001)[110]rotating cubic recrystallization texture and(112)[111]copper texture,mainly due to different thermal-mechanical action in each microzone.The hardness of the weld zone is“W”type distribution,and the lo-west hardness is located in the heat-affected zone of retreating side.The tensile strength of the advancing side and the retreating side of the weld is 496.9 MPa and 505.2 MPa,respectively,reaching 88%and 90%of the tensile strength of the base metal.The tensile strength of the weld nugget zone is 440.4 MPa.The tensile strength of the complete welded joints is the lowest,415.7 MPa.