Characterization of the Trace Phosphorus Segregation and Mechanical Properties of Dual-Phase Steels

摘要

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 diff erent 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(≤0.015 wt%)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 e fficiency of the manufacturing process.