Laser remelting of AISI H13 tool steel: influence of cooling rate on the surface properties

Abstract

Laser surface remelting is an effective and suitable process to extend the longevity of components without additional materials. In this paper, a high energy density laser with a large size was used to improve the hardness of H13 tool steel. A predictive numerical multiphysics coupled model was established to investigate the temperature field and the profile of the molten pool. The effect of laser scanning speeds is investigated in terms of heat-affected depth, surface topography, and mechanical properties. In detail, the simulated temperature gradients with laser scanning speed in a range of 12 to 24 mm s−1 are ∼8.4 × 105 K m−1, involving a cooling rate less than 1 × 104 K s−1 can prevent cracking. The hardness of the remelted zone is in the range of 700–850 HV0.2, and the tensile performances are also recorded. The model in this work could not only link the mechanical properties with process parameters together, but also guide the actual experiment or processing bypassing the trial-and-error method, as well as extend to other materials and laser additive manufacturing.