摘要
Abstract
This study systematically investigates the effect of tool lateral offset on weld formation and joint performance dur-ing friction stir welding(FSW)of 6 mm thick 6005A-T6 aluminum alloy train floor extrusions,and determines the offset tol-erance.Through lateral offset tests(within 1/3 of the pin radius,i.e.,3 mm),a comparative analysis was conducted on the macro/microstructure,hardness,tensile properties,residual stress,and fatigue performance of joints when the tool was offset toward the lap side and the support side.The results show that the offset direction significantly affects the distribution of forging force and joint deformation;offset toward the support side helps reduce the lap gap.The microhardness distribution of the joint exhibits a"W"shape,with the heat-affected zone(HAZ)being the mechanically weak region.When the offset is within the tolerance,the joint tensile strength reaches 211-222 MPa(exceeding 80%of the base metal strength),and fracture occurs in the HAZ on the lap side,with the fracture surface showing typical ductile fracture characteristics.The transverse residual stress distribution is high in the middle and low at both ends,with a maximum value of approximately 169-171 MPa.The fatigue limit is 112 MPa(at 50%survival rate).It is concluded that when the lateral offset is controlled within 1/3 of the pin radius,effective penetration depth can be ensured,deformation controlled,and tunnel or void defects avoided.In practical welding,it is recommended to preferentially position the tool toward the support side of the profile web.关键词
铝合金6005A-T6/搅拌摩擦焊/横向偏移/显微硬度/力学性能Key words
Aluminum alloy 6005A-T6/friction stir welding(FSW)/lateral offset/mechanical properties/fatigue分类
矿业与冶金
