Short Crack Growth and Fatigue Behavior of an aged Second Generation Duplex Stainless Steel

M. AVALOS; M. BALBI; A. EL BARTALI; I. ALVAREZ ARMAS

Hyannis, Massachusetts, USA

Conferencia; Seventh International Conference on Fatigue Damage of Structural Materials; 2008

The kinetics of microcrack growth during cycling has been studied in a S32205 duplex stainless steel in the as-received and aged (100hr at 475¨¬C) conditions. Cylindrical specimens with a shallow notch were subjected to a constant plastic strain range of 0.3% in both thermal conditions. The characteristic features of surface damage and crack growth showed striking differences in micro-crack density, nucleation location and propagation rate between the two thermal conditions even though the fatigue lives are comparable. In the as-received material, microcrack density is low and they nucleate mainly at grain and phase boundaries or secondphase particles. In the aged condition, slip markings first appear in the ferritic phase and they are the preferred site for microcrack nucleation. Crack propagation takes place along slip markings in adjacent grains for crack lengths less than 100 ¥ìm. A comparison between fatigue life and the relevant parameters of a microcrack growth law was made¥ìm. A comparison between fatigue life and the relevant parameters of a microcrack growth law was made