Andoko, Rudy Soenoko, Anindito Purnowidodo, Yudy Surya Irawan
This research was carried out to studythe mechanical properties of nodular cast iron (NCI), particularly in tensile strength, hardness and toughness after being heat treated by two-step austempering. The result, subsequently, is compared with the single-step austemperingone, performed at 900oCaustenite temperature in the holding time of 60 minutes and quenched in the saline solution with various austempered temperatures at 280, 340, and 340oC in the holding time of 60 and 120 minutes. Meanwhile, for the two-step austempering heat treatment, autenization with temperature as equally given in the single-step one, namely at 900oC at the holding time of 60 minutes, is performed. In this performance, the step is initiated by quenching at the initial austempered temperature of 260oC for 60 minutes and followed by gradually increasing the initial temperature into 280, 310, and 340oC, each of which is in the holding time of 60 and 120 minutes. The result of two-step austempering heat treatment towards the mechanical properties show a higher value compared to the single-step one. In this case, the optimum value of the mechanical properties occurred at the tensile strength and hardness at 340oC of austempered temperature with the holding time of 60 minutes and followed by the lower austempered temperatures, namely at 310oC dan 280oC. By contrast, the value of impact toughness decreased at 340oC of austempered temperature with the holding time of 60 minutes. © Research India Publications.
Department of Mechanical Engineering, Brawijaya University of Malang, Indonesia; Department of Mechanical Engineering, Brawijaya University of Malang, Malang, Jl. MT. Haryono 167, Indonesia
