To Study The Optimum Range For Hardness of Austempered Ductile Iron By Using Taguchi Method

Abstract

Austempered ductile iron commonly known as ADI is a type of ductile iron which has undergone a special heat treatment process of austempering. It has been emerged as a material of high interest because of its good combination of properties like high strength with good ductility, good wear resistance and good fatigue strength. The present study focused to find out the effect of heat treatment on hardness of austempered ductile iron. Taguchi Method is used as a design of experiment for analysis the different ranges of hardness. The results revealed that when austenitization temperature increases from 850 to 920 ˚C then hardness decreases from 43.31 to 40.82 HRC, and when the austenitization time increases from 60 to 120 mins, then hardness decreases from 43.33 HRC to 40.8 HRC. The results of austempered temperature showed that hardness decreases from 42.43 HRC to 41.7 HRC when temperature increases from 280 to 350 ⁰C and when austempered time increases from 30 to 90 min hardness decreases from 42.91 HRC to 41.22 HRC. The maximum value of Signal-to-Noise ratio is 28.4, at austenitization temperature is 850 ^oC, austenitization time is 60 min, austempered temperature is 280^oC and austempered time is 30 min, hence this is optimum range of hardness.