Research status of rare earth in advanced high strength steel for automobile

Composition design and optimization is one of the key technologies for strengthening, plasticizing and toughening advanced high-strength steel. With the progress and development of high-purity steel equipment and technology, the application of rare earth elements in steel has gradually changed from purification and inclusion modification to micro-alloying. From the first generation ferrite-based mild steel and high-strength low- alloy steel to the second generation austenite- based ultra - high- strength steel, and then to the third generation high- strength and toughness steel with multiphase, metastable and multi- scale microstructure control, the microalloying technology of advanced high-strength steel has always been an effective measure to control the microstructure and properties. Rare earth atoms have great atomic radius and high affinity with O and S, which can influence the microstructure of advanced high-strength steel in many aspects, such as controlling solidification and solid phase transformation, affecting the diffusion of carbon and alloy elements, and thus have a significant impact on its mechanical properties, formability and corrosion resistance. In this paper, the action mechanism of rare earth elements in the first, second and third generation typical advanced high-strength steels is described, and the application prospect of rare earth elements in future automobile steels is prospected.