A study on the influence of laser hardening on microstructure, and microhardness of additively manufactured H13

Laser surface treatment was employed as a promising approach to enhance the fatigue life of additively manufactured samples by increasing the surface hardness of the material. In this study, H13 tool steel was manufactured using the selective laser melting method, and lines of laser treatment were applied to the surface. Experimental and statistical approaches were utilised to investigate the microstructural changes, microhardness variations, and weld geometry resulting from different laser treatment processes. The aim was to control the laser parameters and analyse the behaviour of the microstructure and hardness profile of the laser-treated zone. The results revealed an amelioration in the hardness of the laser-treated surface, except for the heat-affected zone, which exhibited a lower hardness compared to the substrate. Statistical approaches were employed to study the effect of laser parameters on the weld geometry including width and depth of the laser-treated area using ANOVA method, elucidating the impact of each factor on these values. Finally, a predictive method for estimating the width and depth was proposed, to facilitate the adjustment of laser parameters for achieving specific outcomes, such as desired hardness profiles or geometrical characteristics, in the laser surface treatment process.