Recrystallization and strain accumulation behaviors of high Nb-bearing line pipe steel in plate and strip rolling

Abstract The recovery and recrystallization behaviors of high Mn-high Nb line pipe steel were investigated by means of thermal-simulation and plane strain tests, and the morphology of prior-austenite grains in different conditions was revealed by special etching method. Proposed rolling windows of static recrystallization (SRX) and non-recrystallization were determined for industrial plate rolling. Moreover, partial dynamic recrystallization (DRX) behavior of high Mn-high Nb steel was proved by multi-pass plane strain tests. The results of SRX indicate the existence of a deformation temperature range for grain refinement by complete SRX, in which grains nucleate homogeneously and the coarsening rate is slow because of intense solute dragging. In non-recrystallization temperature range, partial DRX may be triggered by overmuch strain accumulation in the case of improper process design, and then, mixed grains and the loss of final S v level take place.