A new computationally efficient model for tempering in multi-tracks laser hardening in medium carbon steels.

The bottleneck in laser hardening principally occurs when large surfaces have to be treated because this process situation leads to multitrack laser scanning in order to treat all the component surfaces. Unfortunately, multitrack laser trajectories generate an unwanted tempering effect that depends on the overlapping of two close trajectories. To reduce the softening effects, a simulator capable to optimize the process parameters, such as laser power and speed and number and types of trajectories, could sensibly increase the applicability of the process. In this paper, an original model for the tempering is presented. By introducing a tempering time factor for the martensitic transformation, the hardness reduction can be predicted according to any laser process parameters, material, and geometry. Experimental comparisons will be presented to prove the accuracy of the model.