Influence of temperature and section size on fatigue crack growth behavior in NiMoV alloy steel

Abstract The fatigue crack growth characteristics of a forging-grade NiMoV alloy steel were investigated with Wedge-Opening-Loading type crack-notch fracture toughness specimens and the results expressed in terms of the stress intensity factor fracture mechanics parameter. Particular emphasis was placed on the influence of temperature (−100°F to 75°F) and section size (1 in.- and 2 in.-thick specimens) upon the observed fatigue crack growth rate. The results show that the fatigue crack growth rate at a given stress intensity level is dependent upon test temperature and specimen thickness, decreasing as the test temperature decreases and as the specimen thickness increases. In addition, it was found that the fatigue crack growth rate increases as loading conditions deviate from ideal plane strain behavior.