Effect of Austempering Time on Microstructure and Wear Resistance of Ductile Iron Castings

Abstract

An experimental investigation was carried out to study the structure of ductile iron castings which were selected to perform the investigation: 1.4% Ni - 0.3 Mo and 2.4% Ni - 0.3 Mo. After austenitizing at 880℃ for 1.3 hr, the two alloys were austempered at 250An experimental investigation was carried out to study the structure of ductile iron castings which were selected to perform the investigation: 1.4% Ni - 0.3 Mo and 2.4% Ni - 0.3 Mo. After austenitizing at 880℃ for 1.3 hr, the two alloys were austempered at 250℃ and 350℃ for time intervals of 60, 120, 240 minutes. Microstructure observation and measurement of UTS, and adhesive wear resistances were reported as functions of austempering time. The results also showed that the obtained structure properties are not believed to be the best possible, but rather they should be viewed as what can be expected with reasonable controls. Production of a conventional spare gear from austempered ductile iron was aimed and concluded at a later stage. The same casting and treating conditions attributed to the optimum structure properties were used for production of the gear. and 350℃ for time intervals of 60, 120, 240 minutes. Microstructure observation and measurement of UTS, and adhesive wear resistances were reported as functions of austempering time. The results also showed that the obtained structure properties are not believed to be the best possible, but rather they should be viewed as what can be expected with reasonable controls. Production of a conventional spare gear from austempered ductile iron was aimed and concluded at a later stage. The same casting and treating conditions attributed to the optimum structure properties were used for production of the gear.