Fatigue crack initiation behavior in embrittled austenitic–ferritic stainless steel

Fatigue crack initiation behavior in duplex stainless steel was studied in the embrittled condition (aging at 475 °C for 100 h) by interrupting fatigue tests conducted at different Δσ/2 values, identifying the crack initiation sites and relating them to the crystallographic parameters obtained from electron back scattered diffraction scans. From the fatigue crack initiation studies conducted at Δσ/2 = 400 and 500 MPa, it was concluded that the crack initiation sites are the slip markings corresponding to {1 1 1} plane in austenite at 400 MPa and more cracks were observed to initiate at twin boundaries in austenite at 500 MPa in the aged condition.