Ductile cast irons: microstructure influence on fatigue crack propagation resistance

摘要

Microstructure influence on fatigue crack propagation resistance in five different ductile cast irons(DCI) was investigated. Four ferrite/pearlite volume fractions were considered, performing fatigue crackpropagation tests according to ASTM E647 standard (R equals to 0.1, 0.5 and 0.75, respectively). Results werecompared with an austempered DCI. Damaging micromechanisms were investigated according to the followingprocedures:- “traditional” Scanning Electron Microscope (SEM) fracture surfaces analysis;- SEM fracture surface analysis with 3D quantitative analysis;- SEM longitudinal crack profile analysis- Light Optical Microscope (LOM) transversal crack profile analysis.