Microstructure Evolution and Mechanical Properties of Laser Deposition Repairing Ti-6Al-3.5Mo-1.8Zr Alloy

Aiming at service-induced damage in the compressor blades of aerospace engines, the study of the laser deposition repairing (LDR) of Ti-6Al-3.5Mo-1.8Zr (TC11) alloy was carried out. The microstructure evolution of the repaired sample and the changes in mechanical properties under different sampling directions were analyzed. The results showed that the laser deposition repairing zone (LDRZ) has epitaxially grown columnar grains which are composed of acicular α′ phase and fine basket-weave structure. The LDRZ exhibited an average hardness of 403.6 HV_0.5, representing a 16.1 pct increase compared to the basic zone (BZ). Compare with the tensile strength (991 MPa) and elongation (13.8 pct) of the basic sample, the vertical repaired (V-R) samples exhibited a 4.8 pct increase in tensile strength (1039 MPa), and a 18.8 pct decrease in elongation (11.2 pct); the horizontal repaired (H-R) samples exhibited a 13.1 pct increase in tensile strength (1121 MPa), but a 60.1 pct decrease in elongation (5.5 pct). The fracture section of the V-R sample and the substrate exhibited a significant number of dimples, indicating a typical ductile fracture mode. For the H-R sample, the ductile fracture and brittle fracture modes were both presented. This research provides a novel approach for the repairing of titanium alloy aerospace components with desirable properties.