Effect of Ce content on the microstructure and TiN precipitation behaviour of high-titanium steel during slow cooling solidification

Abstract

ABSTRACT This study used high-temperature melting experiments, optical microscopy, and scanning electron microscopy to investigate the effects of various Ce contents (0 wt.%~0.0165 wt.%) on the microstructure and TiN precipitation behavior in high-titanium steel during slow cooling solidification. The findings show that the microstructure of the solidified steel in each experiment are equiaxed grains at a cooling rate of 0.17 ℃/s. TiN mainly precipitates in the Liquid + δ two-phase region in this experimental steel. CeAlO3 and Ce2O2S precipitate before TiN, and their small lattice misfit with TiN (7.55% and 7.90%, respectively) are the primary cause of their propensity to act as the cores of TiN heterogeneous nucleation. The TiN area density in each experimental steel increases from 38.6 no./mm2 → 61.4 no./mm2 → 89.3 no./mm2 → 105.8 no./mm2 when the Ce content in the steel rises from 0 wt.% → 0.0015 wt.% → 0.0058 wt.% → 0.0165 wt.%.