An Assessment of the Microstructure and Mechanical Properties of 0.26% Low Carbon Steel under Different Cooling Media: Analysis by one-way ANOVA

Abstract

This study reports the effect of heat treatment on the microstructure and mechanical properties of 0.26% low carbon steel at 850^oC using different cooling media. Annealing, normalizing and age-hardening heat-treatments were used for the experimental work. Hardness tests, fatigue tests, compression tests and metallography were carried out on the heat-treated and control samples. The results were further analyzed using the one-way ANOVA test. The results obtained showed significant differences in the microstructure and mechanical properties of the different heat-treated samples. The hardness profile determined using a Brinell ball indenter showed decrease in hardness of the heat-treated samples when compared with the control. Normalizing heat-treatment yielded a microstructure of better quality than annealing and age-hardening. A higher compressive strength of 155.97MPa and 151.52MPa was obtained with normalizing and annealing heat treatments respectively in comparison to age-hardening (149.93MPa), and the control test (150.56MPa). Improved fatigue strength was also obtained with annealing heat treatment. ANOVA test confirmed the results at 90% confidence and further showed that there was significant difference between the four test conditions.

Keywords: Heat treatment, mechanical properties, fatigue, ANOVA, steel