Influence of Treatment Time on Microstructure of Intercritical Austempered GGG40 Cast Iron
Erol Kilic Cengiz Bagci Kubilay Karacif
AbstractHaving combine mechanical properties (e.g. strength, toughness and ductility makes the austempered ductile iron (ADI) finding wide range of application areas. In recent years, to obtain greater ductility than that by the conventional austempering process, intercritical austempering process has been focus of researches on ADI. This study deals with intercritical austempering of GGG40 ductile cast iron by isothermally treatment at 350 °C for a range of 25-150 minutes following partly austenizing it at 800 °C and microstructural examination of as-threated cast irons. Digital image processing method was used to determine graphite nodularity having responsibility of ductility and matrix phases influencing other mechanical properties in the cast iron. Results showed that while number of graphite particles decreases, their size and circularity increases with increasing treatment time and a useful austempering range can be defined as 100-150 min.