Computational and experimental study of a melt-hardened zone on a roller modified by wide-band laser treatment

A three-dimensional finite element model has been developed to simulate the wide-band laser remelting process and predict the thermal and mechanical properties in the melt-hardened zone. The simulation of the laser remelting process was performed using the nonlinear thermo-mechanical properties, based on a wide-band heat source model. The temperature fields, phase transformations, hardness and residual stress distributions in the melt-hardened zone were analyzed. In the remelting zone, the transformed volumetric percentage of martensite is beyond 80% and the excessive transformed martensitic structure greatly affects the mechanical properties in the melt-hardened zone with its volumetric expansion effect. After remelting, the hardness can be improved and the residual stress distributed within the melted zone is mainly of the compressive type, while the tensile stress in the heat-affected zone (HAZ) may cause the initiation of cracks. The computational results are in good agreement with experimental measurements.