Manipulating the texture configuration and formability of interstitial-free steels through low-oxygen rare earth addition

The influences of rare earth (RE) addition on stored deformation energy and stored-energy-driven microstructure evolution as well as the resulting texture transformation of ultra-low carbon Interstitial-free (IF) steels were carefully studied in this study, to clarify the micro-alloying effect of RE elements on texture configuration and formability under the dual low-oxygen conditions of molten steel and La-Ce mischmetal. Results indicate that a trace amount of RE addition can significantly reduce the stored energy of cold-rolled IF steels by increasing sub-distorted areas within the deformed matrix. These areas, primarily dominated by the 112 deformation texture, are preferential formation sites for recrystallization γ textures, particularly for the 111 component. In the annealing process, continuous static recrystallization (CSRX) predominantly occurs in these sub-distorted regions. The time-consuming boundary transition from low-angle grain boundary (LAGB) to high-angle grain boundary (HAGB) during CSRX provides favorable time condition for the growth of 111-oriented grains and the formation of corresponding texture. Dissolved RE elements can drag the motion of dislocations and pin the migration of boundaries, thereby significantly prolonging the occurrence time of this transition process and increasing the orientation distribution density of the 111 recrystallization texture, a phenomenon rarely observed in RE-free IF steels. As a result, the distribution density of 111 texture gradually becomes comparable to that of 111 texture, contributing to a higher plastic strain ratio increased by 16%. This work offers theoretical guidance for manipulating the texture configuration and formability of IF steels through low-oxygen RE addition. The micro-alloying effect of RE elements on texture configuration and formability of IF steels was studied under dual low-oxygen conditions. The presence of dissolved RE elements drags dislocation motion and pins boundary migration, thereby significantly delaying the boundary transition from LAGB to (M-) HAGB during CSRX. This delay promotes the growth of 111-oriented grains and the concurrent formation of corresponding texture, as these grains predominantly grow through M-HAGB migration. Consequently, the ODF density of 111 texture becomes comparable to that of 111 texture, contributing to a higher plastic strain ratio increased by 16%. • Micro-alloying effect of RE elements on texture and formability of IF steels was studied under dual low-oxygen conditions. • Trace RE addition can markedly reduce the stored energy of cold-rolled IF steels by increasing sub-distorted areas. • Time-consuming boundary transition from LAGB to HAGB during CSRX promotes the formation of 111 texture. • Dissolved RE elements drag dislocation motion and pin boundary migration, thereby prolonging the boundary transition time.