Comparative study on the repair mechanisms of TIG welding and laser repair for damaged TA15 alloy in aviation

To repair the damaged parts of TA15 alloy components in a certain type of aircraft and ensure that the strength of the repaired area reaches over 95% of the original base material and the plasticity reaches over 60%, laser deposition and TIG welding repair experiments were conducted respectively. The macroscopic and microscopic structures, micro - hardness, and tensile strength after the two repair methods were studied.The results show that: In the heat - affected zone of the TIG - welded repair specimen, coarse α - phases form a basket - weave structure. In the repair zone, columnar crystals are prominent, coarse β - grains and α + β mixed structures are formed, and the thermal cycle causes the growth of base - metal grains. For laser deposition repair, the heat - affected zone is extremely narrow, forming an ultra - fine α + β structure. The size of β - grains in the repair zone is significantly smaller than that of TIG - welded specimens, and the structure is more uniform.In terms of performance, laser deposition repair can more effectively ensure the tensile strength and plasticity of TA15 alloy parts after repair. The average micro - hardness of the parts repaired by laser deposition is 393.6 HV, the average tensile strength is 966.8 MPa, reaching 97.1% of the original base material, and the average elongation at break is 10.8%, reaching 72% of the original base material. After TIG welding repair, the strength reaches 81.2% of the original base material, and the average elongation at break reaches 25.7%.