Fatigue crack propagation in austeno-ferritic duplex stainless steel 22 Cr 5 Ni

Abstract

Fatigue crack propagation in Duplex Stainless Steels (DSSs) is strongly affected by microstructure and therefore by the choice of the steel grade or by the heat treatment conditions. In the present work fatigue behaviour of 22 Cr 5 Ni DSS has been investigated both after solution annealing and after different embrittling thermal cycles. Fatigue tests have been done in air considering the influence of both the stress ratio and the loading direction. Roughness analysis has been performed to point out a relationship between fracture morphology and fatigue crack propagation data and it shows that fracture surface roughness influence on fatigue crack advancing depends on loading conditions. A scanning electron microscope (SEM) fracture surface analysis has been performed to investigate the fatigue crack propagation micro mechanisms in 22 Cr 5 Ni duplex stainless steel.