Non Fracture Prediction of a C-Mn Weld Joint in Brittle to Ductile Fracture Transition Temperature Range

This paper deals with the brittle fracture risk evaluation for a C-Mn weld joint in the upper shelf of the brittle to ductile fracture transition temperature range, with the main objective to develop a predictive criteria, able to demonstrate the complete absence of brittle fracture risk. The question was investigated in the frame of two PhDs. In the first one (V. Le Corre PhD), a critical stress based fracture criterion was proposed, qualibrated and validated against experimental data for the base metal. This work gave promising results with, in particular, the capability of the model to predict non fracture for a cracked pipe submitted to bending at low temperature. In the second one (T.H. N’Guyen PhD), the model was calibrated and applied to the weld joint. The work showed that material heterogeneity of the weld metal must be taken into account in order to obtain a good representation of the fracture behavior. Again, the model was confronted to different specimen geometries and showed its capability to reasonably predict constraint and geometrical effects on the brittle fracture appearance risk. The paper gives a synthesis of the main results obtained during these two PhDs, questions still to be solved and perspectives for the continuation of this work.