Microstructure and properties of welding-rolling composite forming for 6061-T6 aluminum alloy by laser induced arc welding

Aiming at the problem that the mechanical properties of 6061-T6 heat-treat aluminum alloy are seriously decreased after welding due to joint softening, the laser-induced arc filler wire welding and post-weld partial rolling composite forming process is proposed. The partially forced deformation of the residual height of welded joints is used to assist in strengthening the over-aged softening zone of the joint. The results show that the welding-rolling composite forming method can obtain well-formed and defect-free joints. Compared with welded joints, the hardness of welding-rolling composite forming joints is more uniform as a whole, and the hardness value of the most seriously softened position is increased from 71.2 HV to 87.8 HV, which is increased by 23.3%; the average tensile strength of welding-rolling composite forming joints is also increased from 246 MPa to 284 MPa, a relative increase of 15.4%, reaching up to 91.6% of the base metal. The rolling process causes partially forced deformation of the welded joint, and the dendrite crystals in the weld seam zone are compacted. The weld seam becomes wider and squeezes to both sides, and then the heat-affected zone structure is coordinating deformation, resulting in an increase in dislocation density and achieving the strengthening effect for the over-aged softening zone. © 2022, Beihang University Aerospace Knowledge Press. All right reserved.