Counter Laser Treatment for Recovering Deformation of Slender Workpiece

Abstract

Laser hardening, compared to other surface hardening processes, presents several advantages: it can be extremely selective and almost without distortion, it achieves higher levels of hardness and thanks to the rapidity of the heating phase it does not require a quenching medium as the material surrounding the heated layer acts as a heat sink. Nevertheless, in case of workpiece with slim geometry, the thermal stress after the treatment induces a sensible deformation on the treatment direction; this deformation can deeply affect the part ability to fulfil its function and/or its reliability. In this paper a solution to recover the workpiece function ability is presented: a second laser treatment (called counter treatment) was executed on the opposite surface of the treated one to reduce the deformation induced by the first treatment. A numerical model was firstly tested and then used to simulate the counter treatment process and to evaluate the optimum process parameters. Based on the numerical analysis, experimental results show that thanks to this technique it is possible to recover up to 80% of the induced deformation.