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Author: search.filters.author.Udupa, K.R.Subject: search.filters.subject.Austempered ductile iron

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    Development of austempered ductile iron for high tensile and fracture toughness by two step austempering process
    (2008) Ravishankar, K.S.; Udupa, K.R.; Prasad Rao, P.P.
    During conventional austempering austempered ductile iron showed a decrease in fracture toughness with increasing austempering temperature, while the tensile toughness increased. Thus high fracture toughness was associated with low tensile toughness. A two step austempering treatment was then adopted where the samples were first au stem p ered at 3000e for sh ort peri 0 ds varyi ng from 10m in utes to 60 minutes, and then subsequently transferred to a second furnace at 4000e for further austempering for 2 hours. It was found that this resulted in fine ferrite grain size, high carbon content of the retained austenite together with increased stability of the austenite. Under such conditions it was possible to achieve an excellent combination of high fracture toughness and high tensile toughness.
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    Grinding wear behaviour of stepped austempered ductile Iron as media material during comminution of Iron ore in ball mills
    (2010) Raghavendra, H.; Bhat, K.L.; Udupa, K.R.; Rajath Hegde, M.M.R.
    An attempt has been made to evaluate the suitability of austempered ductile iron (ADI) as media material for grinding iron ore in a ball mill. Spheroidal graphite (S.G) iron balls are austenitised at 900°C for 60 minutes and given stepped austempering treatment at 280°C for 30 minutes and 60 minutes followed by 380°C for 60 minutes in each case. These materials are characterised by measuring hardness, analysing X-ray diffraction (X-RD), studying microstructure using optical and scanning electron microscope (SEM). Grinding wear behaviour of these materials was assessed for wear loss in wet condition at different pH value of the mineral slurry and found that the wear rate of grinding media material decreases with increase in pH of the slurry. The wear resistance of ADI balls were compared with forged En31 steel balls and found that the stepped austempered ductile iron is superior to forged En31 steel balls. © 2010 American Institute of Physics.