A new process, based on ring spot geometry, is presented for laser surface hardening of large cylindrical com-ponents. The proposed technique leads to a very hard, deep and uniform treated area along the entire work piece surface without introducing a tempered zone, making the process very attractive compared to conventional induction hardening that exhibits both low energy efficiency and poor flexibility. A complete physical model is presented for the process, together with a study of the influence of process parameters on the final outcome. The results of an extensive validation campaign, carried out following the AISI1040 standard, are also reported.
This article presents an exhaustive mathematical model for the simulation of hypo-eutectoid carbon steel trans- formations during laser hardening. The proposed model takes into consideration all the the phenomena involved in the process with particular attention to implementing easy mathematical formulas in order to optimize the trade-o between the accuracy of the predicted results and the computational times. The proposed model calculates the 3D thermal eld occurring into the workpiece and predicts the microstructural evolution of the target material exploiting an original approach based on the de nition of thermodynamic thresholds. Several parameters and phenomena are taken into consideration in order to accurately simulate the process: laser beam characteristics, scanning strategy of the target and tempering e ect due to mutually interacting beam trajecto- ries.
Laser shock peening is a well-known technology able to enhance the fatigue life of mechanical components by means of the introduction of residual stresses on their surface. These stresses are induced by means of the recoil pressure caused by the abrupt expansion, in a confining medium, of a laser-vaporized coating layer. If high power densities are used the recoil pressure can be high enough to induce compressive residual stresses on the target surface and to modify its mechanical properties. These mechanical properties can be predicted if the recoil pressure of the ablating layer is determined. In this paper the influence of the laser pulse shape on the recoil pressure is determined by means of a proper modeling of the whole process and the difference between cold" and warm" laser shock peening is pointed out.