Competitive mechanism of phosphorus capturing between MC-carbide (M=Ti, Mo) and ferrite/ martensite interface in dual-phase steel

Abstract Segregation behavior and capturing mechanism of phosphorus (P) in dual-phase steel were systematically investigated by Atom probe tomography (APT). The dual-phase steel is composed of lath martensite, irregular ferrite and MC-carbide (M=Ti, Mo). The P is mainly dissolved in ferrite and martensite grains, and a small amount of P segregates around MC-carbide. APT analysis confirms that the carbide is a type of (Ti, Mo) C. The MC-carbide has a competitive advantage over the ferrite/martensite interface in capturing P atoms. Therefore, it can be concluded that P segregation around the MC-carbide weakens P enrichment at the ferrite/martensite interface. In the end, it is expected that the MC-carbide significantly reduces the P damage to the mechanical properties of dual-phase steel, especially the impact properties.