Improving the Ductility of Locally Manuf

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 °C 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 °C 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 ± 373.5 (Vickers Hardness 20) HV20. The martensitic samples had an average hardness value of 5477.0 ± 452.7 HV20. The samples tempered for 1 hour had an average hardness value of 2735.7 ± 577.6 HV20. The samples tempered for 3 hours had an average hardness value of 2470.2 ± 394.3 HV20, while the samples tempered for 5 hours had an average hardness value of 2198.6 ± 387.6 HV20. The as-received samples had an average impact energy value of 109.8 ± 6.8 J. The martensitic samples had an average impact energy value of 40.7 ± 5.0 J. The samples tempered for 1 hour had an average impact energy value of 114.3 ± 6.9 J. The results indicate that tempering significantly improved the ductility of the locally manufactured steel rods.