Influences of Thin Slab Casting and Direct Rolling Process on Nb-microalloyed Low Carbon Hot Strip Steels

摘要

The influences of thin slab casting and direct hot strip rolling (TSDR) on the Nb-microalloyed low carbon hot strip steels have been studied. Through a series of research work with laboratory simulation and with industrial practice, the main features of Nb microalloyed law carbon steels processed by using TSDR in comparison with conventional hot strip rolling (CHSR) have been found and are discussed in the paper. These features are: coarser and inhomogeneous austenite grain size in the pre-rolling slab; more Nb precipitates in slab and in strip; coarser Nb precipitates in slab and more fine NbC_xNy particles in strip; coarser ferrite-pearlite grain size in strip; and lower strength level of TSDR strips.