#surface hardness

As long as industrial and agricultural activities go on, wastes will continue to be generated. In view of this, wastes recycling/or conversion to other reusable materials that can be utilize by another industrial set-up is fast receiving worldwide attention. In this research work, the assessment of the suitability of melon and snail shell wastes mixtures in enhancing the surface hardness of mild steel via the pack carburization method has been investigated. The carburization process was carried out at the temperatures of 9000C, 9200C and 940oC for the soaking times of 15, 30, 45 and 60 minutes respectively, and then quenched in water to harden. Thereafter, they were tempered at 2500Cfor 1 hour to relieve the residual stresses introduced into the steel specimens as a result of quenching. Standard method was adopted to determine the surface hardness of the carburized and un-carburized test specimens. Micro-structure examination was also performed using standard metal lographic techniques to observe the micro structures formed. The results of the study showed increase in the surface hardness of all the carburized steel specimens in the different carburizing media. The steel specimens carburized with 80% snail shell wastes plus 20% melon shell wastes mixture had higher hardness values than those carburized with 100% snail shell wastes only. The maximum surface hardness values of 118VHN, 128VHN and 129VHN were obtained at the carburizing temperatures of 9000C, 9200C and 9400C respectively, for the soaking time of 60 minutes with the specimens carburized with snail and melon shell wastes mix. It was observed that the process variables (temperature and soaking time) significantly impacted on the quantity of carbon absorbed at the steel surface as depicted by the surface hardness values. The results of the research work have established the viability of melon and snail shell wastes mixture as an alternative source of carburizers in enhancing the surface hardness of mild steel.