Anomalous Refinement of the Austenite Grain upon High-Strain-Rate Hot Deformation of Microalloyed Medium-Carbon Steel

Abstract

Dynamic recrystallization (DR) of austenite of a medium-carbon steel microalloyed with titanium, niobium, vanadium, and boron has been studied in the course of deformation treatment in the temperature range of 850–1180°C using strain rates of 1–100 s–1. It has been established that the threshold deformation corresponding to the onset of the DR increases in a regular way with increasing strain rate from 1 to 10 s–1 and decreases sharply at 100 s–1. In this case, fine grains (D ≈ 8 μm) are formed, which evidences the occurrence of a specific mechanism of the formation of the austenite structure.