The role of trace metal elements in steel:

13, niobium (Nb): can make steel grain refinement, reduce the steel's thermal sensitivity and temper brittleness; improve the welding properties of steel, heat-resistant steel to improve the strength and corrosion resistance.

14, Ta (Ta): to improve the quality of steel and mechanical properties, increase the alloy's melting point, high temperature strength, carbide and γ phase stability.

15. Zirconium (Zr): In the smelting process, oxygen, sulfur and phosphorus agents, Zr, Hf can increase the strength and hardness of steel, especially the long-term strength of steel and improve the welding performance of steel.