A Study on the Elasto-Plastic Fracture Toughness $J_IC$ Evaluation of Carbon Steel

탄소강의 탄소성파괴인성 $J_IC$ 평가에 관한 연구

In this study, J-integral values obtained by various methods, i.e, R-Curve, Unloading Compliance, Strectched Zone Width [SZW], and Acoustic Emission [AE] methods are investigated. Elasto-plastic fracture toughness [$J_IC$] estimations by R-curve method are overestimated than those by SZW method, and those by unloading compliance method is around middle value of them. And the difference between them is little. The $J_IC$ value by AE method was almost agreed with that by SZW, and then proved to be useful. Crack propagation mechanism on fractography is a stable ductile fracture. For the identification of ductile fracture, both fractography analysis and AE method were applied to estimate the characteristics more precisely.