Ductile Fracture Resistance Modeling Approach in Two High Grade Steels

Recent developments in ductile fracture resistance measures in high grade steels in the pipeline industry include the crack tip opening angle (CTOA) and “steady state” fracture propagation energy, using 3-point bend specimens. The CTOA has been found to be a function of specimen ligament size. Alternatives would be “steady state” fracture propagation energy, critical fracture strain and adoption of damage mechanisms. This paper focuses on modeling approaches for crack propagation using damage mechanisms. The tension test is used to “calibrate” the damage model parameters and applied to the crack propagation in a 3-point bend specimen in candidate high grade steels. The effects of using parameters developed from tension test and extending to a 3-point bend crack propagation scenario is discussed.