CONICET | Buscador de Institutos y Recursos Humanos

The effect laser shock processing (LSP) with two different swept directions (parallel and perpendicular to rolling direction) on tensile test and high cycle fatigue behavior of 2205 duplex stainless steel (DSS) was investigated. The Nd:YAG pulsed laser operating at 10 Hz frequency and 1064 nm wavelength was used. The energy and pulse density used were 10 GW/cm2 and 2500 pulses/cm2 respectively [1]. The LSP configuration was the water jet mode [2] and without protective coating [3-4]. Notched specimens 4 mm thick were treated on both sides, and then fatigue loading was applied with R = 0.1. The results showed that LSP improved fatigue life without significantly modifying mechanical properties (elastic modulus, yield stress and ultimate tensile stress) in 2205 DSS. The LSP for both swept direction (parallel and perpendicular to rolling direction) eliminates the tensile residual stresses due to manufacturing processes and induces high levels compressive residual stresses in 2205 DSS. However, a higher value of compressive residual stresses using the treatment condition where the swept direction is perpendicular to rolling direction, was observed. The fatigue tests results are consistent according to the measurements of residual stresses. By setting the swept direction perpendicular to rolling direction, the increase of fatigue life achieves a value of 79 % at 275 MPa of stress amplitude, while with the swept direction parallel to rolling direction; the fatigue life improvement is only 35 % at the same stress level. The swept direction perpendicular to rolling direction was the best condition to optimize fatigue life of DSS 2205. In this treatment condition, for values of stress amplitudes between 275-300 MPa, an enhancement of 79% up to 402 % was obtained.