Numerical simulation and experimental study on the heat and mass transfer behavior during the pulsed laser cladding process

Abstract

Compared with continuous wave (CW), pulse wave (PW) perturbation results in a larger temperature change rate inside the cladding layer, which leads to a higher quality cladding layer. In this paper, a three-dimensional numerical model of laser cladding Fe60 powder was established. The multiphysics field coupling transient evolution and solute distribution under PW and CW operating modes were studied. The problem of lack of theoretical support for laser cladding process under different working modes in heat source was solved. Calculations show that at 1970 ms when the temperature is stable, the maximum temperature, flow rate, and stress under the PW mode are 2660 K, 0.34 m/s, and 354 MPa, respectively, which are smaller than those under the CW mode. The four solute distributions at stable temperature are as follows: The minimum mass fractions of Fe and Mn are 87% and 0.49% in the CW mode, and the maximum mass fractions of Cr and Ni are 11% and 5%. In the PW mode, the minimum mass fractions of Fe and Mn are 82% and 0.44%, and the maximum mass fractions of Cr and Ni are 14% and 5%. PW has a smaller heat input than CW, resulting in a smaller molten pool, so the elements in the molten pool are more fully mixed with other alloying elements. Metallographic experiments were performed using a scanning electron microscope to examine the mechanical properties on the fusion cladding layer, and the accuracy of the model was verified by combining numerical simulations with experimental studies for comparative analysis.