Abstract
Two different stress raiser geometries (fillets and notched) were treated by laser shock peening (LSP) in order to analyze the effect of sample geometry on fatigue behavior of 2205 duplex stainless steel (DSS). The LSP treatment was carried through Nd : YAG pulsed laser with 1064 nm wavelength, 10 Hz frequency, and 0.85 J/pulse. Experimental and MEF simulation results of residual stress distribution after LSP were assessed by hole drilling method and ABAQUS/EXPLICIT software, respectively. The fatigue tests (tensile-tensile axial stress) were realized with stress ratio of R = 0.1 and 20 Hz. A good comparison of residual stress simulation and experimental data was observed. The results reveal that the fatigue life is increased by LSP treatment in the notched samples, while it decreases in the fillet samples. This is related to the residual stress distribution after LSP that is generated in each geometry type. In addition, the fatigue crack growth direction is changed according to geometry type. Both the propagation direction of fatigue crack and the anisotropy of this steel results detrimental in fillet samples, decreasing the number of cycles to the fatigue crack initiation. It is demonstrated that the LSP effect on fatigue performance is influenced by the specimen geometry.
Highlights
Two different stress raiser geometries were treated by laser shock peening (LSP) in order to analyze the effect of sample geometry on fatigue behavior of 2205 duplex stainless steel (DSS). e LSP treatment was carried through Nd : YAG pulsed laser with 1064 nm wavelength, 10 Hz frequency, and 0.85 J/pulse
A good comparison of residual stress simulation and experimental data was observed. e results reveal that the fatigue life is increased by LSP treatment in the notched samples, while it decreases in the fillet samples. is is related to the residual stress distribution after LSP that is generated in each geometry type
E numerical simulation of residual stress distribution was used as powerful tools to predict and correlate this result with the fatigue behavior of the 2205 DSS
Summary
By inducing residual compression stresses through the LSP treatment and taking into account the superposition principle, in order to exceed the yield stress in these localized regions, it is necessary that the external load first counteract the compression state induced in the material and, subsequently, begins to deform in a tension state. In this way, the LSP treatment decreases the effect of the applied external load and delays the incubation time of the cracks. Rubiogonzalez et al founded that as the density of pulses increases, the fatigue crack growth rate decreases in compact tension samples of Al-6061-T6 [2] and 2205 DSS [3]. e fatigue life behavior as function of laser swept direction was optimized for bending fatigue in Ti-6Al-2Sn-4Zr-2Mo [4]
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