Multiphase ferrite-bainite-martensite microalloyed steel produced through a two-step cooling followed by annealing route and a ferrite-pearlite steel obtained through air-cooling after forging were subjected to turning operation. The influence of process parameters such as cutting speed, feed and depth of cut on surface roughness on both materials was compared. The results show that the multiphase microalloyed steel exhibited high surface finish than air-cooled steel. The analysis of variance shows that the contribution of cutting speed and depth of cut on surface roughness are insignificant for both ferrite-bainite-martensite and ferrite-pearlite microstructures. © IMechE 2014.