Effect of Processing Parameters on Interphase Precipitation and Mechanical Properties in Novel CrVNb Microalloyed Steel

Abstract

Novel steel microalloyed with 0.73 (Cr + V + Nb) has been subjected to thermomechanical processing (TMP) with varying parameters to simultaneously maximise the steel strength and ductility. Optical and electron microscopy studies coupled with uniaxial tensile testing were carried out to analyse the processing-microstructure-properties relationship. For the suggested steel composition, the simultaneously highest yield stress (960 MPa), ultimate tensile strength (1100 MPa), and elongation to failure (25%) were achieved following simulated coiling at 650 °C and holding for 30 min. The variation in the finish rolling temperature affects the ferrite grain size and the ratio of precipitates formed in austenite and ferrite. If a significant amount of solute is consumed for precipitation in austenite and during subsequent growth of strain-induced precipitates, then a lower fraction of interphase and random precipitates forms in ferrite resulting in a lower strength. Extended time at a simulated coiling temperature resulted in the growth of interphase precipitates and precipitation of random ones in ferrite. Fine tuning of TMP parameters is required to maximise the contribution to strength arising from different microstructural features.

The Effect of Strain in Recrystallization Region on Interphase Precipitation and Mechanical Properties of Ferritic Microalloyed Steels

“…For the current study, it can be speculated that HRS High V steel exhibits lower work hardening at the early stage of plastic deformation. Kostryzhev et al [ 71 ] have shown the relation between higher strength and lower work hardening rate of same steel processed under different conditions (finishing rolling temperature 900 °C, simulated coiling temperature 650 °C, and holding time 1800 s).…”