Mixed-Mode Fatigue Crack Growth in Stainless Steels Under Biaxial Loading

Mixed-Mode fatigue crack propagation tests were carried out in stainless-steel cruciform specimens in which a center initial crack oriented at 45 deg was loaded biaxially. When the loadings were in-phase, the crack was deflected with the initial crack growth angles less than 50 deg and when they were out-of-phase, it was branched with the initial crack growth angles larger than 50 deg. In all the cases, the deflected or branched cracks propagated in Mode I, namely /ΔK II was almost always zero along the crack paths. The relationship between deflected or branched cracks during propagation was also analyzed.