EXPERIMENTAL STUDY ON THE EFFECT OF HEAT TREATMENT ON THE PROPERTIES OF DUCTILE IRON AFTER ALLOYING

Cast Iron, the first man – made composite, is at least 2500 year old. It remains the most important casting material, with over 70 % of the total world tonnage. The man for cast iron longevity are its wide range of mechanical and physical properties coupled with its competitive price. Ductile iron or popularly known as spherodized graphite iron (SGiron) is a special variety of cast iron having carbon content more than 3 % and has graphite present in compact, spherical shapes. These compact spheroid hamper the continuity of the matrix much less than graphite flakes which results in higher strength and toughness with a structure that resembles gray cast iron , thus imparting superior mechanical properties i.e. much higher than all other cast irons and which can be compared to steel .This unique property enables ductile iron to be used for numerous industrial applications .The excellent combination of mechanical properties obtained in S.G. iron can further be improved by the heat treatment . The most recent development in this regard is the production of Austempered Ductile Iron (ADI). It provides an excellent combination of high tensile strength, wear resistance along with good corrosion resistance and quite significant amount of ductility. Due to these factors, S.G. or ductile iron is austempered when a very favouurable combination of various properties is required. But this type of treatment is bit tricky, since it require controlled heating and isothermal holding of the material. So it is necessary to find some attractive methods for property development in S.G. iron.The present work is an attempt to study the properties enhancement of ductile iron by heat treatment. Normalizing, Austenitization, Quenching & Tempering, Austempering methods are applied to study the hardness, tensile strength, and impact strength of the material. The mechanical properties obtain by various technique have been compared to one another using two different grades of S.G. Iron (one with copper and another without copper). The effect of copper has been studied.