Abstract:

The static recrystallization (SRX) and precipitation behavior of a weathering steel microalloyed with vanadium were investigated through double-pass compression tests under controlled conditions using the MMS-300 thermal-mechanical simulator. The deformation temperatures ranged from 800 °C to 1000 °C, and the inter-pass time from 1 s to 500 s. The simulation results showed that SRX occurred after 5–10 s at the first compression deformation. The softening fraction of SRX was found to increase with increasing the deformation temperature and the pre-strain. However, the softening fraction scarcely changed during the process of strain-induced precipitation. In addition, the kinetics of SRX was described by the Avrami equation, and the Avrami exponent appeared to be closely associated with the deformation temperature. The microstructure evolution was investigated at the initiation and completion of recrystallization. The amount and distribution of the precipitates were analyzed. The relationship between the driving force of SRX and the pinning force of precipitation was discussed. Besides, the recrystallization inhibition was detected at the early stage of precipitation, and the pinning forces were found to be of a magnitude comparable to the driving force. Moreover, the pinning forces were found to increase with the degree of precipitation and reach a peak at the intermediate stage of precipitation, and finally reduce as the particles coarsened.

Key words: Vanadium-microalloyed weathering steel, Static recrystallization, Kinetics of SRX, Microstructural evolution, Precipitation