3D modelling of LASER hardening and tempering of hypo-eutectoid steels

In this paper a mathematical model solved by means of the finite differences method (FDM) for laser surface hardening of complex geometries is presented. The 3-D transient model characterizes a software package named Laser Hardening Simulator (LHS), which makes it possible to predict the extension of the treated area into the mechanical components and thus the hardened depth into the bulk material. The obtained microstructures and the resulting hardness with respect to the laser parameters and to the laser beam path strategy can be determined by considering the quenching and the tempering effects due to the overlapping trajectories. The initial workpiece microstructure is taken into account in the simulation by a digitized photomicrograph of the ferrite-pearlite distribution before the thermal cycle. In order to show the accuracy of the model, experimental trials were conducted on the keyway for spline machined on a hub made of SAE 1043. The domain discretization for the solution of the heat flux problem into the workpiece and for the diffusion of the carbon is carried out by means of a mesh generator strategy implemented into the code.