Engineering materials, mostly steel, are heat treated under controlled sequence of heating and cooling to alter their physical and mechanical properties to meet desired engineering applications. In this study, the effect of heat treatment (annealing, normalising, hardening, and tempering) on the microstructure and some selected mechanical properties of NST 37-2 steel were studied. Sample of steel was purchased from local market and the spectrometry analysis was carried out. The steel samples were heat treated in an electric furnace at different temperature levels and holding times; and then cooled in different media. The mechanical properties (tensile yield strength, ultimate tensile strength, Young's modulus, percentage reduction, percentage elongation, toughness and hardness) of the treated and untreated samples were determined using standard methods and the microstructure of the samples was examined using metallographic microscope equipped with camera. Results showed that the mechanical properties of NST 37-2 steel can be changed and improved by various heat treatments for a particular application. It was also found that the annealed samples with mainly ferrite structure gave the lowest tensile strength and hardness value and highest ductility and toughness value while hardened sample which comprise martensite gave the highest tensile strength and hardness value and lowest ductility and toughness value.

Corrosion of metal components constitutes a major challenge in many engineering systems, with appropriate design, proper material selection, and heat treatment as commonly used control strategies. In this study, the corrosion behaviour of heat-treated (annealed, normalised, hardened, and tempered) NST 37-2 steel in three concentrations (1.0, 1.5 and 2.0 M) of hydrochloric acid solution was investigated using weight loss and electrode-potential methods. Results showed that corrosion rate increased with increase in acid concentration. The decreasing order of corrosion resistance was Tempered > Annealed > Normalised > Hardened > Untreated. The surface pictures of the heat-treated and untreated samples showed uniform and pitting corrosion with the latter becoming more pronounced as concentration increased.

Given the significant scale of the textile industry, there has been rising global concern over the sustainability of this sector. Consumers’ satisfaction with textile materials plays a pivotal role in sustainable textile products in competitive markets. There have been limited studies on understanding customers preferences and the selection criteria for sustainable textile products in developing countries, where the uncertainties of demand and supply abound. The sustainability impact of textile products in developing countries has not been thoroughly investigated in previous studies. This study aims to examine sustainability criteria to evaluate the selection of sustainable textile products. Thus, using a case study of the textile industry in Nigeria, this paper provides a fuzzy decision support system to analyze the selection of sustainable textile products in the country's textile industry. The study employed an integrated fuzzy best-worst method and fuzzy inference systems to evaluate textile products. The fuzzy best-worst method was used to calculate the weight of each criterion while a fuzzy inference system was employed to select the best product. The proposed method was utilized in a real-world case study, and some managerial implications were determined. Based on three distinctive evaluative assessments, the proposed method was shown to be valid and robust.

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