Study on serration flow and dynamic strain aging of Cr–Ti–B low-carbon steel

Abstract

Compression tests were carried out for hot-rolled Cr–Ti–B low-carbon steels with different Cr contents (low Cr and high Cr) at three strain rates (0.01, 0.1 and 1 s−1) and temperatures ranging from 250 to 650 °C. The serrated flow and dynamic strain aging (DSA) behaviors during deformation were systematically analyzed. The results showed that the effect of the strain rate on serration flow is more obvious than that of the deformation temperature, and the serration type changes from type C to type A with increasing strain rate. The occurrence temperature range of DSA in high Cr steel (350–450 °C) is higher than that in low Cr steel (300–400 °C) at a strain rate of 1 s−1. The activation energy for DSA close to that for the diffusion of carbon, which is considered to produce DSA. A Cr–C cluster is observed in high Cr steel, which clarified that the delaying mechanism throughout the DSA regime is attributed to the pinning of carbon diffusion by Cr atoms.

Keywords

• Cr–Ti–B low-Carbon steel
• Serrated flow
• Dynamic strain aging
• Dislocation
• Interstitial atom