Estimation of fracture toughness of cast steel container from Charpy impact test data

摘要

Fracture energy values KV have been measured on cast steel, used in the container manufacture, by instrumented Charpy impact testing. This material has a large ductility on the upper transition region at +20 degrees C and a ductile tearing with an expended plasticity before a brittle fracture on the lower transition region at -20 degrees C. To assess the fracture toughness of this material we use, the K-IC-KV correlations to measure the critical stress intensity factor K-IC on the lower transition region and the dynamic force - displacement curves to measure the critical fracture toughness JPC, the essential work of fracture Te on the upper transition region. It is found, using the K-IC-KV correlations, that the critical stress intensity factor K-IC remains significant, on the lower transition region, which indicating that our testing material preserves his ductility at low temperature and it is apt to be used as a container's material. It is, also, found that the J(p)-p energetic criterion, used on the upper transition region, gives a good evaluation of the fracture toughness closest to those found in the literature. Finally, we show, by using the T-e-K-IC relation, on the lower transition region, that the essential work of fracture is not suitable for the toughness measurement because the strong scatter of the experimental data. To complete this study by a numerical approach we used the ANSYS code to determine the critical fracture toughness J(ANSYS) on the upper transition region.