Predictive modeling and the effect of process parameters on the hardness and bead characteristics for laser-cladded stainless steel

Abstract

Laser cladding is a novel additive manufacturing and surface treatment process associated with many interactive process parameters. Using the response surface method with a central composite design, a structured design of experiments approach was chosen to examine the influence of selected process parameters on the bead geometry and hardness for single-track laser-cladded specimens using AISI 420 stainless steel powder on a AISI 1018 substrate. In the present study, robust predictive models for hardness, bead aspect ratio, and wetting angle with the substrate were determined using multiple regression analysis. The geometry and hardness relationships to the process inputs were evaluated using F-statistics from the analysis of variance and compared by utilizing perturbation plots, 3D surface mapping, and contour plots. The highly coupled non-linear relationships are evident from these analyses, but this study revealed that the laser speed has the most significant effect on the bead microhardness and the powder feed rate was found to be the most significant parameter for these bead geometry parameters. The perturbation plots confirmed this sensitivity of those process parameters. This research study gives a guideline for the selection of appropriate process parameters for the laser cladding process to achieve desired hardness and bead geometry.