Effect of Processing Parameters on Properties of Alloyed Austempered Ductile Iron

摘要

Ever since its discovery in 1948, the use of ductile iron is increasing continuously, this is due to the combination of its various excellent mechanical properties of the material. Extensive research is being carried out to develop even better properties. Austempered ductile iron is the most recent development in the area of ductile iron or S.G. iron. This is formed by an isothermal heat treatment of the ductile iron. The newly developed austempered ductile iron is now replacing steel in many fields so it is becoming very important to study various aspects of this material. In the present work the effect of Copper and Nickel as alloying element along with the process variables (austempering temperature and austempering time) on the properties (Hardness, Tensile strength and Elongation) and microstructure of ductile iron has been studied. With increasing austempering time hardness, tensile strength and elongation are increasing but with increasing austempering temperature hardness and tensile strength are decreasing and elongation increasing. Austempered ductile iron with alloying element (Cu or Ni) is showing some higher strength, hardness and lower elongation than the unalloyed austempered ductile iron. In microstructure ferrite is increasing with increasing austempering time and austenite is increasing with increasing austempering temperature in all the Cu alloyed, Ni alloyed and unalloyed grades.