FATIGUE PERFORMANCE AND RESIDUAL-STRESSES IN LASER TREATED 50CRV4 STEEL

The effects of continuous CO2 laser surface quenching of one side of a rectangular section of 50CrV4. steel samples are studied. The treatment is carried out in one or several passes, working with a square beam with a uniform power density of 2550 W cm(-2) at scan rates between 700 and 1400 mm min(-1), with either a single or overlapped sweep of the beam. The magnitude and distribution of internal longitudinal stresses created by the uniform treatment of the surface, relating them to the harness gradients created in depth, conditioned by structural variations, are considered. The uniform treatment of the surface leads to considerable improvement in fatigue performance. In the presence of the thermally affected zones produced by successive sweeps of the beam, however, the noted improvement is largely lost.