Interphase Precipitation in Cold-Rolled Dual-Phase Steel Strip: Design and Challenges

In microalloyed steels, interphase precipitation involves the formation of precipitates at the ferrite/austenite interface during their transformation. The study on interphase precipitation has been ongoing since the 1970s and remains highly relevant today. While this metallurgical approach has been applied in various products of advanced steels, its application to cold-rolled steels is still absent. This study presents a development of cold-rolled dual-phase (DP) steels strengthened by interphase-precipitated carbides. A CALPHAD-based approach is established to facilitate austenite to ferrite transformation coupled with interphase precipitation during simulated annealing for cold-rolled DP steels. Further experimental investigations on the effects of V and Mo optimize the alloy composition, and the corresponding nano/microstructures are validated by transmission electron microscopy (TEM) and atom probe tomography. Besides, this work further addresses the impacts of interfacial segregation and microsegregation bands on the capability of interphase precipitation in the studied steels. In summary, this work charts a new pathway for the development of cold-rolled DP steels strengthened by interphase-precipitated carbides, advancing the realm of high-strength steels. This study validates a CALPHAD-based approach in designing a prototype of cold-rolled dual-phase (DP) steel with interphase precipitation. Impacts of interfacial velocity and interfacial segregation on interphase precipitation in V-Mo microalloying steels is investigated via detailed nano/microstructural characterizations. The findings summarize design principles and challenges in the development of cold-rolled DP steel strengthened by interphase-precipitated carbides.image (c) 2024 WILEY-VCH GmbH