EFFECT OF COKE SIZE ON THE MECHANICAL AND WEAR PROPERTIES OF CARBURIZED MILD STEEL

Abstract

The aim of this research is to investigate the effect of various coke sizes on the carburizing process of mild steel, this effect is evaluated through measurement of the mechanical properties and wear resistance for different carburizing condition therefore five sets of samples were prepared and carburized at different temperatures and times. Three sets were carburized at 850oC, 900 oC and 950oC for 120 min. while two other sets are carburized at 1000oC and 1050 oC for 60 min. All sets were carburized using three different sizes of coke namely A (< 0.4 mm), B (1 : 1.6 mm) and C (4 : 5 mm ). After carburization all sets were quenched in water and then tempered at 200oC for 15 min. After tempering, different mild steel samples were subjected for microstructure observation, hardness test, Charpy impact test, tensile testing and adhesive wear test. The experimental results were analyzed and shows that mild steels carburized at 1050oC with intermediate coke grain size B (1 ~ 1.6 mm) gives the optimum results for the mechanical and wear properties which may be due to the microstructure obtained at this temperature (martensitic case and bainitic core). This indicates that coke size B gives the optimum combination of surface area and porosity needed for the reaction kinetics.