Metallurgical and Materials Engineering- Scholarly Publications

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    Open Access
    Effects of Velocity of Impact on Mechanical Properties and Microstructure of Medium Carbon Steel during Quenching Operations
    (Scientific Research Publishing Inc. (Engineering), 2015-07-17) Agboola, J.B.; Abubakre, O.K.; Mudiare, E.; Adeyemi, M.B
    Theoretical analysis of the effects of the velocity of impact using suitable heat transfer equations expressed in forms of finite difference method was developed and used to determine their effects on the characteristic cooling parameters during the quenching process. Various velocities of impact obtained by varying the heights of specimen drops were also used to experimentally determine their effects on characteristic cooling parameters and mechanical properties of medium carbon steel using water as the quenching medium. At a height of drops of 0.5 m, 1.0 m, 1.5 m, and 2.0 m, the tensile strength of the material is 410.4, 496.12, 530.56, and 560.40 N/mm2 respectively. The corresponding hardness values are 42.4, 45.2, 46.2, 50.5 HRC respectively. It is found that as the velocity of impact increases, the maximum cooling rate increases. Hardness and ultimate tensile strength also increase. There are good agreements between theoretical and experimentally determined values of critical cooling parameters of water during quenching operations.
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    Open Access
    Effects of Bath Temperature on Cooling Rate, Mechanical Properties and Microstructure of Medium Carbon Steel during Quenching Operations
    (Journal of Energy Technologies and Policy, 2015) Agboola, J.B.; Abubakre, O.K.; Mudiare, E.; Adeyemi, M.B
    The effects of variations of bath temperatures of Selected Nigerian Vegetable oils on cooling rates, mechanical properties and microstructure of the quenched steel samples were investigated in this work. Cooling curves at different bath temperatures have been experimentally determined. From the cooling curves, the cooling ability variations were then analysed. The results obtained show that increasing bath temperatures increased the cooling rates of the quenched steel. These cooling rates are found to enhance mechanical strength with limited ductility of the quenched carbon steel. The hardness and tensile strength for palm kernel quenched sample increased from 40.8 HRC to 43 HRC. However, percentage elongation and impact values decreased from 0.28% to 0.21% and 9.5 N/mm2 to 7.5 N/mm2 respectively as bath temperature increases from 35 °C to 100 ºC. The results also showed that the microstructure of the quenched steel samples can be changed and significantly improved by varying the bath temperature. Reasons for variation in mechanical properties and microstructure are discussed
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    Open Access
    Physico-chemical Characteristics and Fatty Acids Composition of Some Selected Nigerian Vegetable Oils for Quenching Medium
    (British Journal of Applied Science & Technology, 2015-04-08) Agboola, J.B.; Abubakre, O.K.; Mudiare, E.; Adeyemi, M.B.; Hassan, S.B.
    Four vegetable oils (cottonseed oil, palm kernel oil, neem seed oil and palm oil) were characterized with respect to their physicochemical properties and fatty acids profiles with the aim of investigating their suitability as quenching media for medium carbon steels. The physicochemical properties were determined by using appropriate ASTM methods. The fatty acid ester compositions were determined by a gas chromatographic analysis procedure. The results obtained showed that the different vegetable oils exhibited different viscosity and viscosity-temperature behaviour corresponding to their varying molecular structures and level of saturation. The following values were obtained for the various physicochemical parameters measured in cottonseed oil, palm kernel oil, neem seed oil and palm oil: viscosity values at 40ºC were (34.8, 41.69, 32.41 and 39.7) cSt; viscosity values at 100°C were (6.9, 8.94, 7.89 and 8.2) cSt; the Iodine values were (115.09, 19.59, 120.16 and 35.90) g I2/100 g while the acid values were (1.80, 0.22, 12.97 and 1.23) mgKOH/g respectively. The level of saturation of the fatty acids followed the decreasing order of palm kernel oil (0.25), palm oil (0.92), cottonseed oil (1.35) and neem seed oil (1.39). The results obtained showed that the vegetable oils under study are suitable as potential quenching media for carbon steels with palm kernel oil being the most suitable followed by cottonseed oil and neem seed oil. The least suitable among the oils is palm oil.
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    Open Access
    Performance Assessment of Vegetable Oil and mineral oil blends during heat treatment of Medium Carbon Steel
    (International Journal of Microstructure and Materials Properties, 2016) Agboola, J.B.; Abubakre, O.K.; Edeki, M.; Adeyemi, M.B
    A comparative study was carried out to investigate the suitability of some selected Nigerian vegetable oils as alternative quenchant to SAE40 engine oil for industrial heat treatment of Medium Carbon steels. The study involved the characterization of physicochemical properties and fatty acid profile of cottonseed oil, palm kernel oil, neem seed oil and palm oil. The quenching performance of these vegetable oils was conducted at quenchant bath temperatures of 34˚C, 50˚C, 70˚C, and 100˚C. SAE40 engine oil (Standard quenchant) and tap water served as control. The effect of cooling rates of the quenching media on mechanical properties and microstructure of the quenched steel samples were investigated. The results obtained show that the different vegetable oils have different viscosity and viscosity-temperature behaviour just as their molecular structures were different. The mechanical properties of the as-quenched specimens in these oils show that the hardness of steel quenched in palm kernel oil was highest at 40.85HRC. As received sample absorbed the highest amount of energy (183 J) before fracture while the sample quenched in water absorbs the least energy (28 J). Hence vegetable oil is suitable as an alternative quenchant to petroleum-based SAE40 engine oil for quenching medium carbon steels, without cracking or distortion, the most suitable among them being palm kernel oil.
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    Open Access
    STUDY OF TRIBOLOGICAL PROPERTIES OF TRAIN BRAKE BLOCK PRODUCED FROM CLAY BLENDED WITH STEEL SLAG
    (Journal of Engineering Research, 2020) Obidiegwu, Eugenia O.; Ochulor, Ezenwanyi F.; Mgbemere, Henry E.
    Rail transportation is one of the most important and economical transportation systems. Thus, this paper investigates the tribological properties of composites produced from clay blended with steel slag for the train brake block application. The problem with conventional brake blocks currently in use by the Nigerian Railway Corporation (NRC) is that the friction between the brake blocks and the train wheel leads to wear of the brake surface. This wear puts the safety of the passengers and freight being transported in jeopardy. Wearing of the brake surface renders the brake block unsafe for use. Furthermore, the brake blocks currently in use are imported, this frequent importation increases the cost incurred in maintaining and operating trains. Also, the importation of the brake blocks hinders the development of our local industries. In this study, brake block samples were produced using clay and steel slag. Clay served as the matrix, while induction furnace steel slag served as the reinforcement. Phenolic resin was used as the binder and quartz was added to improve friction properties. The Vickers micro hardness (HV), coefficient of sliding friction and wear rate of the produced brake block composite was evaluated. It was observed that the sample with composition: clay- 39%, steel slag-27%, phenolic resin-20% and quartz- 14% gave improved properties of: wear rate – 6g/min, hardness- 6.65HV and coefficient of friction-0.5774. From the results obtained, this study has established that clay and steel slag can be used to produce brake block composites with the required service properties which can serve as a viable alternative to imported brake blocks.