The one-step cladding by using a high power direct diode laser (HPDDL) compared to a CO2 or a Nd:YAG laser is found to be a cost-effective process for repairing or building valued components and tools that are used in an automotive, aerospace, nuclear, and defense industries. Whereas, number of processing parameters such as laser power, scanning speed, powder feed rate, laser focal spot, and thermo-physical properties of the materials are involved in the process to achieve the desired geometrical features (size and shape) of the clad, and the surface properties (hardness, resistance to heat, wear, and corrosion). Numerical simulation is a cost-effective technique to predict the effect of processing parameters on the variation of geometry of the clad and the surface properties.
In this study, an experimentally-based finite element (FE) thermal model coupled with thermo-kinetic equations is developed to predict the temperature history and hardness of the cladding process. The temperature-dependent material properties and phase change kinetics are taken into account in this model. As-used experimental boundary conditions are adopted in this model.
A 2-kW direct diode laser of 808 nm in wavelength, rectangular-shaped laser spot of 12 mm×1 mm with uniform distribution (top-hat) of laser power is used to carry out the experiments. An off-axis powder injection system is used to deposit tool steel H13 on the AISI 4140 steel substrate. Metallurgical characterization and hardness measurements are performed to quantify the effect of processing parameters on the variation of geometrical features of the clad and its hardness.