Matrix influence on fatigue crack propagation in spheroidal cast irons

摘要

Microstructure influence on fatigue crackpropagation considering two spheroidal cast irons, characterisedby a ferritic-perlitic microstructure (percent ferrite 80 percent)and a perlitic microstructure (percent perlite > 95 percent)respectively, was investigated. This analysis was performedconsidering the influence of stress ratio (R = 0.1, 0.5, 0.75).Tests were performed in laboratory conditions, with a loadingfrequency of 20 Hz. Fracture surfaces were analysed both bymeans of a scanning electron microscope1 (SEM) andperforming a fracture surface roughness analysis in order toinvestigate the crack advancing micromechanisms and toquantify the influence of crack surface roughness on crackclosure effect, respectively.