Relationship between microstructure and mechanical properties in Nb–V microalloyed TRIP steel

Abstract

Nb–V additions clearly affected the precipitation state, respective phase transformations and final microstructure, and in turn, resulting mechanical properties of an intercritically annealed transformation induced plasticity sheet steel. As the precipitation hardening played a limited role in the overall strengthening, the grain refinement was the prevailing strengthening mechanism associated with the addition of the Nb–V microalloying to a basic TRIP780 composition. In addition to this, the microstructural changes, resulting from the addition of microalloying, lowered the stability of retained austenite, which decreased the elongation of the steel. Nevertheless, using this microalloying concept, an exceptional product of R m xA 80 exceeding 16 000 MPa could be achieved.