Effect of austempering process parameters on the mechanical properties of ductile cast iron quenched in moringa seed oil
Date
2020
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Abstract
The use of Austempered Ductile Iron (ADI) is rapidly gaining ground because of its excellent properties such as high strength, high wear and abrasion resistance, excellent fatigue, high toughness and high strength-to-weight ratio, that are suitable for most of engineering applications. However, determination of the right process parameters needed to developADI products with combination of desirable properties that are most appropriate for specific application is a major challenge that faces production and material design engineers. There is need to ensure that ADI materials are either over-or under- processed to guarantee the development of the candidate material required for an engineering application. Hence, the effects of austempering process parameters on the mechanical properties of austempered ductile cast iron were studied. Ductile cast iron was developed by alloying cast with 0.06% magnesium. The cast samples were machined and then austenized at 9500C, held at this temperature for 1 hour before quenching in moringa seed oil. Thereafter, the samples were subjected to isothermal treatment at different austempering temperatures of 2400C, 3500C and 4200C for different time durations of 2.5, 3.5 and 4 hours. The samples of the austempered ductile cast iron were examined for microstructural details and then subjected to tensile testing, hardness and percentage elongation. The results obtained within the time range of 2.5 – 4 hours for the various temperatures of 2400C, 3500C, 4200C indicate that the values of tensile strength, hardness and percentage elongation were within the ranges of 1151 – 849MPa, 306 – 267BHN and 2.86 – 5.97% respectively. It was found that austempering temperature range of 350 - 4200C yielded increase in percentage elongation with decrease in tensile strength and hardness. This is due to the presence of coarser ausferrite matrix with higher amount of carbon diffusion. However, lower temperature austempering process such as 2500C showed improved tensile strength and hardness with low ductility. This shows that optimum tensile strength value of ADI is obtainable at low austempering temperature while maximum elongation requires higher austempering temperature. It was therefore concluded that at specific austempering temperature, the mechanical properties of austempered ductile cast iron could vary with time and temperature. Thus, there is a strong correlation between specific engineering properties of austempered cast iron and the austempering parameters
Description
This research was conducted in collaboration with a staff of FUTO. It contains tables and figures
Keywords
Tensile strength, cast iron, quenching, ductility, hardness, austempering, Department of Mechanical Engineering
Citation
Chima, O. M., Onuoha, C., Nwokeocha, T. O. & Uwalaka, A. (2020). Effect of austempering process parameters on the mechanical properties of ductile cast iron quenched in moringa seed oil. IOSR Journal of Mechanical and Civil Engineering, 17(5), 21-27