Dynamic Fracture Toughness and Fatigue Crack Growth Rate Properties of ASME SA508 CL 3 and SA508 CL 3a Base and Heat-Affected-Zone Materials

Dynamic fracture toughness tests were performed on ASME SA508 Cl 3 and Cl 3a base and heat-affected-zone (HAZ) materials. Linear elastic results of dynamic iniation fracture toughness obtained under fast or rapidly applied loading rates KId were obtained at low temperatures while J-integral techniques were used to evaluate dynamic fracture toughness over the transition and upper shelf temperature ranges. Loading rates in terms of stress intensity factor rate ˙K averaged 5.35 × 104 MPa · m1/2/s (4.83 × 104 ksi · in.1/2/s). Tension, Charpy impact, drop weight nil-ductility transition (NDT), and room temperature, air environment fatigue crack growth rate (FCGR) tests were also performed. From a dynamic fracture toughness as well as FCGR standpoint, SA508 Cl 3a steel can be considered as an acceptable alternative to the more commonly used SA508 Cl 2a pressure vessel steel, especially for structural applications in which underclad cracking is a potential problem.