Effect of Monotonic and Cyclic Loading on the Fracture Behavior of SA 333 Steel

The fracture resistance behaviour of SA 333 Gr 6 steel has been studied, as a part of the assessment of the structural integrity of the primary heat transfer piping of nuclear power plants. The microstructure of the steel and its relevant mechanical properties such as hardness, tensile and impact properties have been characterized. A series of tensile tests and a few strain rate change tests have been carried in the temperature range of 28o to 300oC. Monotonic J-R curves of the material have been determined in the temperature range of 28-300oC, whereas cyclic crack growth resistance curves have been determined at the stress ratios of R = 0, -0.5, -0.8, -1.0 and –1.2, and for three plastic displacement levels 0.5, 0.3 and 0.15mm at the ambient temperature. Fractographic studies and examinations of crack tip profiles of specimens interrupted during monotonic and cyclic J tests have been carried out