Impact of Varying Austempering Treatment Parameters on Mechanical and Wear Properties of Austempered Ductile Iron

Austempering temperature and time play an important role in the austempering mechanism and microstructural evolution of the l austempered ductile iron (ADI) part. In this study, as cast ductile iron (DI) samples were subjected to austempering treatment by adopting varying austempering temperatures of 300 oC, 350 oC and 400 oC and times of 20, 40 and 60 minutes. Samples were subjected to microstructural analysis via optical microscopy (OM) and Scanning electron microscopy (SEM), mechanical property testing, wear and X ray diffraction (XRD) analysis. Austempered samples consisted of needlelike and feathery ausferrite phase. The highest and lowest ultimate tensile test (UTS) values observed were 740 MPa at 300 oC for 20 minutes and 538 MPa at 400 oC for 60 minutes respectively. The UTS and vickers hardness of all austempered samples were higher than that of as cast sample’s value of 480.3 MPa and 380 Hv respectively. Highest percent elongation of 7.7% was observed using 400 oC for 60 minutes. The austempered samples had lower wear rates than their as cast counterpart. XRD patterns revealed growth of the ausferrite phase as austempering temperature increased. This study has established that there exists a crucial interplay between austempering temperature and time during austempering process.