The application of the 'local approach' to cleavage fracture of ferritic steels and their weldments - A review

TWI Industrial Member Report Summary 478/1993

By C S Wiesner

Background

Single-parameter fracture mechanics describes the fracture toughness of a material by global parameters such as the stress intensity factor or the crack tip opening displacement which, within certain limits, are representative of the stress/strain field ahead of a crack. An alternative approach for the description of fracture is theapplication of a local fracture criterion which is based on the micromechanisms of the fracture event and which assumes that fracture takes place if a critical stress or strain state is reached in the vicinity of the flaw. This methodology for the prediction of fracture is known as the 'Local Approach'. This report assesses the current state of knowledge of the 'Local Approach' to cleavage fracture, reviews application to ferritic steels and their weldments and addresses limitations and disadvantages of the methodology.