A thermo-mechanical model for simulating the temperature and stress distribution during laser cladding process

摘要

During the laser cladding process, thermal stresses are induced because of the high-energy input, high temperature gradient, fast cooling rate, and inconsistency of the clad-substrate material. The induced thermal stresses not only increase the crack tendency, but also influence the mechanical performance of the deposited layer. In this study, a three dimensional (3D) uncoupled thermo-mechanical finite element (FE) model was established to simulate the stress evolution of laser cladding of cobalt-based coatings on mild steel A36. The temperature field was simulated first and then used as transient thermal loading to simulate the stress evolution. Stress distributions for three cases: single track on a flat substrate, double-track on a flat substrate, and double-track on a cylindrical substrate, were investigated in detail. To check the accuracy of the simulation results, validation experiments were carried out using an 8-kW high-power direct diode laser. The thermocouples were used to monitor the temperature cycles at several marked points. The cross-sections of single and double tracks on a flat substrate obtained experimentally were compared with the simulation results. The residual stress on the clad was experimentally determined by an X-ray diffraction machine. The experimentally obtained data showed a significant consistency with the prediction results.