The segregation behavior of trace amount of phosphorus (P) and the mechanical properties of dual-phase (DP) steels have been systematically studied. The microstructure of DP steels is mainly composed of martensite, ferrite and nanoscale carbides. For the DP steels with different trace amounts of P (≤ 0.015 wt%), P has almost no effect on the mechanical properties. Atom probe technology (APT) analyses confirm that P segregation was only found at the precipitate/matrix interface. Moreover, the precipitates of (Ti, Mo) C are widely distributed in the ferrite, martensite and ferrite/martensite interface regions. The special segregation feature of P would not concentrate at specific regions such as ferrite/martensite interface and/or martensite lath interface, which reveals that trace amounts of P (≤ 0.015wt%) have almost no effect on the mechanical properties of DP steels. It is proved for the first time that the MC-type carbides of (Ti, Mo) C can reduce or eliminate the damage effect of P on the mechanical properties of steels, which provides a new way for the design of alloys to reduce P damage. This work will promote to increase the P content control standard in DP steels from 0.01 to 0.015 wt%, which will not change the mechanical properties, but greatly reduce the scrap rate and increase the energy efficiency of the manufacturing process.

系统研究了微量磷（P）的偏析行为和双相（DP）钢的力学性能。DP钢的显微组织主要由马氏体、铁素体和纳米级碳化物组成。对于具有不同微量 P（≤ 0.015 wt%）的 DP 钢，P 对力学性能几乎没有影响。原子探针技术 (APT) 分析证实 P 偏析仅在沉淀物/基质界面处发现。此外，(Ti,Mo)C的析出物广泛分布在铁素体、马氏体和铁素体/马氏体界面区域。P的特殊偏析特征不会集中在铁素体/马氏体界面和/或马氏体板条界面等特定区域，这表明微量P（≤0. 015wt%)对DP钢的力学性能几乎没有影响。首次证明(Ti,Mo)C的MC型碳化物可以降低或消除P对钢力学性能的损伤作用，为合金设计减少P损伤提供了新途径. 这项工作将推动将DP钢的P含量控制标准从0.01wt%提高到0.015wt%，这不会改变机械性能，但大大降低废品率并提高制造过程的能源效率。