Evolution of inclusions in Ti-Ce-Mg deoxidized steel and its effect on acicular ferrite transformation in simulated welding HAZ

The characteristics of non-metallic inclusions in Ti-Ce-Mg deoxidized steel and their influence on the microstructure and toughness of welding heat-affected zone (HAZ) were studied. Results showed that Ti-Ce-Mg deoxidation led to a refined inclusion size and an increase in the number of inclusions below 1 μm. The highest acicular ferrite fraction was obtained in the HAZ of Ti-Ce-Mg steel, and the impact toughness was significantly improved. Ti-Ce deoxidation enhanced the stability of Ti-containing oxide, while Mg treatment promoted its fine dispersion. The final formation of composite inclusions of Ti-Ce-Mg oxide with TiN and MnS enhanced the ability to induce acicular ferrite transformation.