Microstructural and Macrostructural Modeling of the Fracture Behavior of Pearlitic Gray Irons

Abstract

An attempt is made to rationalize the fracture behavior of pearlitic gray irons on both the microstructural and macrostructural levels. Along with the effects of inoculation, those of as-cast section size and carbon equivalent may be rationalized on the basis of coarseness and volume fraction of the weak graphite flakes present in the structure based upon Hornbogen and Motz microstructural model. On the macrostructural level, however, the eutectic cell size is the single most important parameter controlling fracture behavior of gray irons. An analytical model is developed to predict the fracture toughness as a function of notched tensile strength and eutectic cell size. Analytical predictions on both the microstructural and macrostructural levels compare well with experimental results.