Investigation on Effect of Material Compositions on Machinability of Carbon Steels

Abstract

Steels are basically classified based on their carbon contents. In view of this, the processing of steels is greatly affected by their composition, particularly their carbon content. This paper reports on the machinability of three different steels with varying carbon contents. The steel samples were sourced from Owode metal market in Ilorin, Kwara State and their percentage compositional analysis was carried out at Universal Steels Limited, Lagos. The steel samples were classified into high, medium and low carbon steels based on their percentage carbon content. The machining condition was wet and the machining parameters used were depth of cut (0.2 – 0.6 mm), feed rate (0.05 – 0.15 mm/rev), and cutting speed (100 - 150 rpm). The experimental runs were designed using Taguchi orthogonal array of Minitab version 16 and the cutting temperature was monitored with a digital thermometer and k-type thermocouple wires. The experimental results were analysed using Minitab 18 with a focus on percentage contribution of various factors affecting surface roughness, chip morphology, cutting temperature and material removal rate. Results show that surface finish is highest in low carbon steel and lowest in high carbon steel. The responses show that machinability of the steel improved with a reduction in carbon content.