Improvement of Microstructure and Mechanical Properties of Hot-Formed Steel with Ce Addition

In this article, the effect of Ce element on the microstructure and mechanical properties was studied by Ce addition to the hot-formed steel. Scanning electron microscope and energy dispersive spectrometer (SEM-EDS) was used to analyze the improvement effect of Ce on inclusions and the effect of inclusions on fracture behavior; Electron back scattering diffractometer (EBSD) was used to analyze the refinement and strengthening effect of Ce on martensitic grains; transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM) was used to analyze the microstructure strengthening effect and microalloying effect of solid solution Ce in hot-formed steel. Through a systematic analysis of mechanical properties and microstructure, the mechanism of Ce enhances the strength and elongation of hot-formed steel was clarified. Besides, this work provides a research basis for further improving the safety and machinability of hot-formed steel. The mechanism of Ce improves the strength and elongation of hot-formed steel is mainly modified inclusion and microalloying. The modification of nonmetallic inclusions by Ce improves the fracture behavior of hot-formed steel. Meanwhile, lattice expansion caused by solid solution Ce leads to the formation of substructure with high density dislocation and tiny twins, and enhances the strength of martensitic structure.image (c) 2024 WILEY-VCH GmbH