The role of austempering parameters on the structure and mechanical properties of heavy section ADI

In this study the effect of the austempering parameters on structure and mechanical properties of specimens made from 75 mm. ductile iron Y-block with the composition of 3.5% carbon, 2.5% silicon, 1.1% nickel, 0.6% copper, 0.23% molybdenum, and 0.3% manganese was studied. The austempering carried out at 315 and 350 degreesC for 30, 60, 120, 180, 240, and 360 min. The results showed that the austempering times for optimum mechanical properties of austempered materials at 315 and 350 degreesC were 240 and 180 min, respectively. The results also indicated that austempering at 350 degreesC, in comparison with austempering at 315 degreesC, results in higher ductility and toughness and lower strength and hardness. It was also noticed that in a Y-block, the best mechanical properties are achieved near the bottom of the Y-block. (C) 2004 Elsevier B.V. All rights reserved.