Browsing by Author "Acharya, P."

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Influence of Austempering Heat Treatment on Microstructure and Mechanical Properties of Medium Carbon High Silicon Steel
(Institute of Physics Publishing michael.roberts@iop.org, 2017) Acharya, P.; Ravishankar, K.S.
In the present investigation, the influence of austempering heat treatment on the microstructure and mechanical properties of medium carbon high silicon steel was evaluated. The test specimens were machined from the as-received steel and were first austenitised at 900 Â°C for 45 minutes, followed by austempering heat treatment in salt bath at various temperatures 300 Â°C, 350 Â°C and 400 Â°C for a fixed duration of two hours, after that those specimens were air-cooled to room temperature. The characterization studies were carried out using optical microscope, scanning electron microscope (SEM) and x-ray diffractometer (XRD) and then correlated to the hardness and tensile properties. Results indicate that, the specimens austempered at lower temperature i.e. at 300 Â°C, which offered high hardness, tensile strength and lower ductility (1857 MPa and 13.3 %) due to the presence of acicular bainite i.e. lower bainite and also some martensite in the microstructure. At 350 Â°C, reduction in the tensile strength and hardness was observed, but comparatively higher ductility, which was favored by the presence of bainite laths i.e. upper bainitic structure along with higher retained austenite content. Finally at 400 Â°C, reduction in both ductility and tensile strength was observed, which is due to the precipitation of carbides between the banite laths, however good strain hardening response was observed at austempering temperatures of 350 Â°C and 400 Â°C. Â© Published under licence by IOP Publishing Ltd.
Microstructure and wear behavior of austempered high carbon high silicon steel
(2018) Acharya, P.; Kumar, A.; Bhat, R.
In the present investigation, the influence of austempering temperature and time on the microstructure and dry sliding wear behavior of high silicon steel was studied. The test specimens were initially austenitised at 900�C for 30 minutes, thereafter austempered at various temperatures 280�C, 360�C and 400�C, for varying duration from 30 to 120 minutes. These samples after austempering heat treatment were subsequently air cooled to room temperature, to generate typical ausferritic microstructures and then correlated with the wear property. The test outcomes demonstrate the slight increase in specific wear rate with increase in both austempering temperature and time. Specific wear rate was found to be minimum at an austempering temperature of 280�C, that exhibits lower bainite microstructure with high hardness, on the other hand specific wear rate was found to be slightly high at increased austempering temperatures at 360�C and 400�C, due to the upper bainite structure that offered lower hardness to the matrix. The sample austempered at 280�C for 30 minutes offered superior wear resistance when compared to other austempering conditions, mainly due to the presence of fine acicular bainitic ferrite along with stabilized retained austenite and also some martensite in the microstructure. � The Authors, published by EDP Sciences, 2018.
Microstructure and wear behavior of austempered high carbon high silicon steel
(EDP Sciences edps@edpsciences.com, 2018) Acharya, P.; Kumar, A.; Bhat, R.
In the present investigation, the influence of austempering temperature and time on the microstructure and dry sliding wear behavior of high silicon steel was studied. The test specimens were initially austenitised at 900Â°C for 30 minutes, thereafter austempered at various temperatures 280Â°C, 360Â°C and 400Â°C, for varying duration from 30 to 120 minutes. These samples after austempering heat treatment were subsequently air cooled to room temperature, to generate typical ausferritic microstructures and then correlated with the wear property. The test outcomes demonstrate the slight increase in specific wear rate with increase in both austempering temperature and time. Specific wear rate was found to be minimum at an austempering temperature of 280Â°C, that exhibits lower bainite microstructure with high hardness, on the other hand specific wear rate was found to be slightly high at increased austempering temperatures at 360Â°C and 400Â°C, due to the upper bainite structure that offered lower hardness to the matrix. The sample austempered at 280Â°C for 30 minutes offered superior wear resistance when compared to other austempering conditions, mainly due to the presence of fine acicular bainitic ferrite along with stabilized retained austenite and also some martensite in the microstructure. Â© The Authors, published by EDP Sciences, 2018.