Study of crack orientation and fatigue life prediction in biaxial fatigue with critical plane models

•Biaxial fatigue behaviour was characterised in initiation and propagation stages.•Crack growth rate at initiation showed oscillations due to microstructure.•Propagation stage has been studied with the help of five critical plane models.•Models’ performance was evaluated in terms of crack orientation and fatigue life.•The overall best predictions were obtained by FS model.

The crack initiation and propagation behaviour of St52-3N steel is investigated under biaxial conditions. Short crack behaviour is studied and pearlite bands are found to modify the crack growth rate. The behaviour under proportional and non-proportional (90°) loading is studied with different critical plane models; Wang–Brown, Fatemi–Socie, Smith–Watson–Topper, Liu I and Liu II. Smith–Watson–Topper and Liu I are found to best predict the crack orientation under proportional loading and Fatemi–Socie and Liu II under non-proportional loading. The best predictions in terms of fatigue life are obtained by Fatemi–Socie, both under proportional and non-proportional loads.