THE RELATIONSHIP BETWEEN MICROSTRUCTURE AND THE J-R CURVE

A model is presented that establishes a quantitative relationship betw een the J(IC) and the J-R curve and the microstructural parameters, su ch as inclusion size and spacing, and the plastic deformation properti es of ductile materials, such as yield strength and strain hardening e xponents. The model assumes that ductile crack growth occurs by void n ucleation, growth, and coalescence. Each of these processes is modeled in the crack tip environment to complete the model. The proposed mode l is evaluated using tests performed on 303 stainless steel (SS) at ro om temperature and on 1Cr-Mo-0.25V steel at 565 degrees C. Satisfactor y agreements are obtained between the experimentally obtained JR curve s and those predicted from the model. Limitations of the model are als o discussed.