Interphase precipitation of Cu in dual-phase steel

Two experimental 0.2C steels with 1 wt% and without Cu were studied. A dual ferritic-martensitic microstructure was prepared by controlled rolling and subsequent quenching. The heterogenous microstructure was obtained due to the severe cooling of the surface layer during the rolling process. The surface layer of the sheet had a significantly finer ferritic grain than the sheet's core. Mechanical properties of the core were not correlated to the Cu content, whereas the surface layer revealed Cu-related strengthening due to Cu precipitation. Rows of particles typical for interphase precipitation were observed in some of the ferrite grains of the Cu-containing sample. Mode of the ferrite growth from austenite has apparently a crucial role in Cu ability to rapidly precipitate in ferrite grain during or shortly after its formation.

Automated summary

Two experimental 0.2C steels with and without 1 wt% Cu were subjected to controlled rolling and subsequent quenching to form a dual ferritic-martensitic microstructure. The severe cooling of the surface layer during the rolling process resulted in a heterogenous microstructure with significantly finer ferritic grains in the surface layer compared to the core. Mechanical properties of the core were unaffected by Cu content, whereas the surface layer exhibited Cu-related strengthening due to Cu precipitation. The mode of ferrite growth from austenite plays a crucial role in the rapid precipitation of Cu in ferrite grains during or shortly after their formation.