CHARACTERISATION OF RECYCLED STEEL IN NIGERIA FOR QUALITY ASSESSMENT

Abstract

The chemical and mechanical properties of recycled mild steel from scraps in Nigeria was investigated using the mechanical (strength of materials) testing approach, chemical (elemental composition) testing approach and metallurgical (microstructural analysis) testing approach methods. The aim of this study is to investigate the quality of recycled mild steel reinforcement used for engineering applications in Nigeria by obtaining as produced mild steel samples of 12mm diameter rod used for reinforcement for engineering applications in Nigeria from twenty five (25) steel plants located across the six (6) geopolitical zone in Nigeria. The elemental composition test, ultimate tensile strength test, the microstructural analysis and determination of hardness of samples from each steel plants were carried out on the mild steel of 12mm diameter rod used for reinforcement for engineering applications in Nigeria. The result of ultimate tensile test UTS reveals that out of twenty (25) steel plants A to Y, from which samples of 12mm steel rod was tested, only nine (9) steel plants were able to produced quality steel in accordance with the British Standard. The majority of the steel plants produced steel were below the British Standard. From the result obtained from elemental composition, virtually most of the steel produced from Nigeria steel plants contain excessive carbon content. It was also revealed from the result of elemental composition that, out of twenty five (25) steel plants, only two (2) steel plants conformed with the British BS: 4449 standard of carbon content at 0.25 (wt % C), twenty three (23) steel plants were having excessive or high carbon contents which did not conform with the British BS: 4449 standard. Finally, based on the results obtained from this study, most as-produced mild steel from the twenty five (25) steel plants in Nigeria did not meet the British BS: 4449 standard, and are not suitable for reinforcement of building structures.