Potentiality of Small Punch Test Using Damage Model to Generate J-R Curve of 20MnMoNi55

摘要

This study explored the determination of J-R curve and J_i (fracture toughness) of nuclear structural materials using small punch test of 3 mm disk. The punch load versus central deflection data are collected up to fracture which is signified by the rapid drop in load carrying capability of the specimens. The experimental data for 20MnMoNi55 material is then used to evaluate yield strength and ultimate tensile strength making use of available correlations in the previous studies. These material data are then used to calculate Ramberg-Osgood hardening exponent leading to the generation of complete true stress-strain data. The next task is to determine GTN parameters of the materials which can simulate average P/t_0~2 versus biaxial strain up to fracture. These GTN parameters along with true stress-strain data are then used to generate J-R curves of the materials by finite element modeling of ASTM standard CT specimen. Calculated J-R curves are then compared with the experimental values of previous studies. The proposed methodology has the potential to determine J-R curve and J_i (fracture toughness) of irradiated material using small punch test.