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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/12689

Title: A study on how to improving the ductility of locally manufactured steel rods by tempering
Authors: Martin, H. A.
Nunoo, O. A.
Dadson, A. B. C.
Issue Date: 2020
Abstract: Heat treatment was conducted to improve the ductility of locally manufactured mild steel rods (Fe-0.26 %C) obtained from Ferro-Fabrik, Tema, using tempering. Microstructural studies, hardness, impact and tensile tests were carried out on the mild steel rod samples before and after heat treatment. The samples were heated to 950 ℃ to austenitize them for 1 hour and rapidly quenched to room temperature in water to produce martensites. They were then re-heated to the tempering temperature of 500 ℃ for 1, 3 and 5 hours. Some of the martensitic samples were not tempered after quenching. The as-received samples (non-heat treated samples) had an average hardness value of 2290.5 (Vickers Hardness 20) HV20. The martensitic sample had an average hardness value of 5477.0 HV20. The samples tempered for 1 hour had an average hardness value of 2735.7 HV20. The samples tempered for 3 hours had an average hardness value of 2470.2 HV20 while the samples tempered for 5 hours had an average hardness value of 2198.6 HV20. The as-received samples had an average impact value of 109.8 J. The martensitic sample had an average impact energy value of 40.7 J. The samples tempered for 1 hour had an average impact value of 114.3 J. The samples tempered for 3 hours had an average impact value of 139.8 J; while the samples tempered for 5 hours had an average impact value of 141.1 J. From the tensile test the average percentage elongation of the as-received samples was 30.8 %. The martensitic sample had an average percentage elongation value of 17.5 %. Whereas the samples tempered for 1, 3 and 5 hours had an average percentage elongation of 25 %, 30.0 % and 32.5 % respectively. The as-received and the martensitic samples had average percentage area reductions of 65.0 % and 42.5 % respectively. The samples tempered for 1, 3 and 5 hours at 500 oC had average percentage area reductions of 57.3 %, 64.0 % and 65.8 % respectively. The microstructure of the tempered samples revealed the formation of even distribution of ferrite and pearlite. The above results suggest that the ductility of locally manufactured mild steel rods may be improved by tempering.
URI: http://hdl.handle.net/123456789/12689
Appears in Collections:College of Science

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