FATIGUE PROPERTIES OF SOLUTION STRENGTHENED FERRITIC DUCTILE CAST IRONS IN HEAVY SECTION CASTINGS

Recently, standardized solution strengthened ferritic ductile cast irons (SSF-DI) have met the interest of the industrial world due to their improved mechanical properties and workability compared to standard ferritic-pearlitic ductile cast irons. However, the limited number of experimental data and the lack of production experience make the introduction of these new alloys to the market very difficult. For this reason, mechanical and fatigue properties of heavy section SSF-DI castings have been examined. Metallographic analyses have been performed using optical microscopy to identify the most important microstructural parameters. Fracture surfaces of fatigue specimens have been investigated using a Scanning Emission Microscope in order to identify crack initiation and propagation zones. Fatigue curves of SSF-DI have been finally compared with those obtained from traditional ductile cast iron specimens taken from the same casting geometry