Prediction of SENB fracture toughness from charpy data using the beremin model in the lower transition region

This work focuses on the application of a mechanistic local approach model to describe the statistical distribution of experimental Charpy (CVN) impact test data obtained at several temperatures in the ductile to brittle transition temperature range. The current objective is to develop a correlation in the lower transition regime between quasi-static CVN absorbed energy (CVE) and the J-integral fracture toughness (J_c) obtained from deeply pre-cracked Charpy (PCCVN) specimens tested quasi-statically to laboratory test standards. The Beremin model for cleavage fracture has been applied to a ferritic steel which has been comprehensively tested using standard CVN, shallow U-notched and PCCVN specimen types in the lower ductile to brittle transition. This has enabled a prediction to be made of the absorbed CVE at cleavage fracture initiation for a Charpy specimen tested quasi-statically in the lower part of the CVN transition curve. By applying the Beremin model to PCCVN single edge notch bend specimens at quasi-static rates it was possible to use the Weibull stress, to achieve a reliable correlation between CVE and J_c in the lower ductile to brittle transition region. The results from this work indicate that the Beremin model can provide a theoretically based correlation for CVE to J_c fracture toughness for a ferritic steel under quasi-static loading conditions. The overall objective of the project remains to predict dynamic CVN absorbed energy using micro-mechanical modelling and which is valid for all ferritic steels.