Effects of Excess C on New Grain Formation and Static Recrystallization Behavior at Shear Bands in Cold-Rolled Ultra-Low Carbon Steel Sheets

Abstract

The effects of excess carbon on static recrystallization of cold-rolled steel sheets were studied using Ti-bearing ultra-low carbon steels with and without carbon in solution. Here, excess carbon means solute carbon added beyond the atomic equivalent ratio with Ti. Static recrystallization was evidently accelerated by the presence of excess carbon. Microstructural observation confirmed that statically recrystallized grains were generated at ferrite grain boundaries and deformation bands. Preexisting fine grains also stimulated static recrystallization. However, nucleation at deformation bands was not particularly significant in Ti-bearing ultra-low carbon steels without excess carbon. This difference derived from excess carbon is discussed in detail in relation to stored energy, preferential nucleation sites of static recrystallization and grain boundary migration.