Microstructure-property relationship in a low carbon Nb-B bearing ultra-high strength steel by direct-quenching and tempering

This work describes here the synergistic effect of niobium micro-alloying in combination with boron addition on the development of a 900 MPa grade ultra-high strength low carbon cost-effective bainitic steel processed by direct-quenching and induction tempering. A mixed microstructure consisting of acicular ferrite and lath bainite associated with high density of high angle grain boundaries was obtained by controlled rolling and …