Role of Synthetic Slag Treatment on the Morphology of Non-Metallic Inclusions and Subsequent Cold Drawability of the High Carbon Wire Rod Steel

The present work discusses the evolution of microstructure and non-metallic inclusions during wire drawing process in a synthetic slag-treated 5.5 mm diameter high carbon wire rod steel. It has been observed that failure of the as-received wire rod (without synthetic slag treatment) takes place at different stages of deformation during wire drawing operation. However, in case of the synthetic slag-treated wire rods (TW specimen), failure takes place consistently at ~ 95% reduction in the cross-sectional area of the wire. In a quest to understand the failure mechanisms during wire drawing process, a systematic study has been carried out by analyzing the microstructures and non-metallic inclusions in the steel wires drawn at various stages of deformation. The improved drawability of the treated wire specimens is attributed to the decrease in the amount of unfavourable non-deformable inclusions in the steel matrix, and this stems from the synthetic slag treatment of the liquid steel. Microstructural investigation also confirms the complete realignment of pearlite colonies along the wire drawing direction followed by thinning and disintegration of cementite lamellae at higher deformation, particularly in case of the synthetic slag-treated wire rod steel.