Three-Dimensional Numerical Simulation of Repairing Process by Laser Direct Energy Deposition

In recent years, technology to properly repair damage detected during periodic inspections has been necessary to continue to use aging infrastructure. In the past, weld overlay repair was the most common repair technique. This study examined the possibility of laser direct energy deposition (LDED) repair technology, and its tensile and fatigue strength properties were compared to other typical repair methods. The LDED technique was found to be superior to other repair methods in terms of interfacial strength and mechanical properties. In this study, a finite-element (FE) simulation was performed by combining the heat conduction equation involving the liquid-/solid-phase transformation and the Chaboche-type inelastic constitutive equation. The LDED process was modeled by defining the deposition layer as a virtual rectangular region and allowing the stiffness and thermal properties of the region to overlap the laser irradiation region. The results showed that the temperature history and strain behavior estimated from the FE results are in good agreement with the experimental results. It was also confirmed that the residual stresses formed in the deposited layer were slightly above the yield strength of the base material, which were significantly lower than those formed by the weld overlay.