Effect of microstructural features on ductility of drawn pearlitic carbon steels

The effect of microstructural features on ductility of cold drawn pearlitic steels containing 0.52-0.92 wt% C was investigated. The relationship between ductility and microstructural features of interlamellar spacing, ferrite thickness and cementite thickness, was closely examined, compared with that with drawing strain. The variations of reduction of area (RA) with drawing strain well reflected the microstructural evolution occurred during wire drawing; RA increased initially with the progressive realignment of randomly oriented cementite, showed a maximum peak due to the completion of the alignment of most cementite, and decreased with thinning or fragmentation of the aligned cementite. Among factors on ductility, cementite thickness was found to be the most dominant microstructural feature for RA of drawn pearlitic wires, regardless of transformation temperature and carbon content in steels. Additionally, the presence of the specific cementite thickness for the maximum RA in drawn steel wires was observed as about 0.006-0.009 mu m.