Microstructure and Mechanical Properties in Progressively Drawn Pearlitic Steel

Abstract

This paper studies the relationship between the microstructural changes caused by the cold drawing process in pearlitic steel wires (axial orientation of the pearlitic lamellae together with decrease of the average interlamellar spacing) and the improvement of their mechanical properties. The strength is related to plastic strain by means of the Embury-Fisher equation, and also by a new Hall–Petch expression, where to calculate the distance between barriers against dislocational movement one must consider, apart from the average interlamellar spacing, the average orientation angle. A modelling of the evolution of pearlitic lamellae with cold drawing was made, assuming that initially all angles appear with the same probability, that lamellae change their geometry along the longitudinal section of the wire similarly to the specimens and that the projection of the average interlamellar spacing on the cross section of the wire is proportional to the specimen diameter. The results obtained with this modelling show a good correspondence with experimental data.