Microstructure and mechanical properties of a 2 wt% Nb bearing low carbon steel

Abstract

Design of advanced alloys with simple compositions is a new strategy to improve the recyclability of the alloys. In this study, a 2 wt% Nb bearing low carbon steel (2Nb steel) without addition of Ni, Cr and W was designed and processed by hot forging. The as-hot-forged steel shows a fine grain size microstructure with NbC precipitates formed. Microstructure and tensile properties were characterized at ambient and elevated temperatures. The yield stress and ultimate tensile stress of the as-forged 2Nb steel are 339 MPa and 498 MPa at room temperature, 297 MPa and 430 MPa at 600 °C, respectively. The good high temperature strength was related to the pinning effect of large NbC precipitates present at the grain boundaries and small precipitates formed in the grain interior that hinder the movement of grain boundaries and dislocations, respectively.