Measurement of dynamic strain aging in pearlitic steels by tensile test

Abstract

The mechanical behavior of a pearlitic steel was studied by means of tensile tests performed in the temperature interval from 298 to 773 K, at strain rates from 10-4 to 10-2 s-1. aiming to analyze the role of cementite decomposition in the dynamic strain aging (DSA) phenomena occurring in these steels. Typical features of DSA were observed: serrated flow (the Portevin-LeChatelier-PLC effect), the presence of a maximum and a minimum in ultimate tensile strength and reduction of area versus temperature curves, respectively, and a less evident maximum in the yield strength versus temperature curve. Apparent activation energies were calculated based on the onset of the PLC effect, the maximum in ultimate tensile strength and the minimum in reduction of area. Results suggest that changes in mechanical properties associated with DSA in pearlitic steels are related to cementite decomposition. Differences on the phenomenological aspects regarding DSA in pearlitic and in low carbon steels are discussed, based on the kinetics of the process.