Teruaki Yamada

Preliminary Finite Element Analysis of Shot Peening for Austenitic Stainless Steels

In this study, the preliminary finite element analysis of shot peening was carried out in order to investigate the fundamental mechanism of shot peening for stainless steels. For numerical simulations with high-rate deformation such as shot peening, rate-dependence plasticity models are necessary to get better analysis results. Therefore the stress-strain relation at high-strain rates of austenitic stainless steels were obtained by split Hopkinson pressure bar (SHPB) tests. The parameters of Johnson-Cook plasticity model were determined from the result, and then the finite element analysis of shot peening was carried out using the parameters. Consequently, the compressive residual stress was created beneath the surface of the target but was changed to the tensile residual stress with an increase in the depth.

Measurement of Crystal Grain Size of Austenitic Stainless Steels under Low-Cycle Fatigue by EBSD Techniques

Electron backscatter diffraction (EBSD) in conjunction with scanning electron microscopy was used to assess the fatigue damage induced in stainless steels. The parameter of the crystal grain size was devised in order to evaluate the fatigue damage in terms of the crystal grain size. It was concluded that the fatigue damage could be evaluated by the EBSD measurements using the relationship between the total strain range, the number of cycles and the crystal grain size.