EXPERIMENTAL INVESTIGATION ON LASER PEENING OF ADDITIVELY MANUFACTURED TI6AL4V ALLOY

摘要

Laser additive manufacturing is widely utilized to fabricate Ti6Al4V alloy, but post-processing is necessary to improve its performance for fatigue resistance of some critical components. This paper proposes laser peening (LP) as an effective way to improve the surface integrity of Ti6Al4V alloy fabricated by direct laser deposition (DLD). After laser peening, little difference of surface roughness is observed. Compressive residual stresses are induced on the top surface layer. The maximum value of compressive residual stress is about -520 MPa and the compressive state extends to the depth of 0.60 mm. In addition, the relative densities of specimen are measured using the Archimedes method. The average porosity is observed to decrease due to plastic deformation at the surface layer. Results of fatigue test show that the service cycle can be improved about three times.