Mechanisms of Serrated Flow and Microstructural Evolution in MarBN Steel

The mechanisms of serrated flow and microstructural evolution in MarBN steel were studied under two strain rates (5 × 10-3 s-1 and 5 × 10-5 s-1) at room temperature and high temperatures (430 °C and 630 °C). The experimental results show that the type-C serrations occurred at all temperatures under a high strain rate of 5 × 10-3 s-1. In contrast, type-B serrations occurred at 430 °C and 630 °C under a low strain rate of 5 × 10-3 s-1, indicating that the type of serrated flow was related to the strain rate. The microstructural results reveal that pinning and unpinning dislocation under both strain rates were responsible for the serrations at both strain rates.