DAMAGE MECHANISMS AND LOCAL APPROACH TO FRACTURE- Part II: Brittle fracture prediction in the ductile to brittle transition

摘要

In this work, the use of statistical local approach to fracture in the ductile-to-brittle transition region is examined. The Beremin model is applied to predict the cleavage fracture probability. The Weibull parameters are identified from instrumented Charpy test results and with the finite element analysis. These parameters are then used for the prediction of probability distribution of the fracture toughness in the DBTT range. The Weibull parameters were found to vary with temperature. However, taking into account the evolution of cleavage micromechanisms in a phenomenological way, i.e. evolution of Weibull parameters with temperature is not sufficient to predict correctly the fracture toughness from the Charpy impact tests. The influence of other variables as e.g. strain rate on the fracture criterion is discussed.