Interphase precipitation hardening of a TiMo microalloyed dual-phase steel produced by continuous cooling

摘要

Precipitation hardening is a promising way to strengthen the ferrite phase in dual-phase steels. This work studied the microstructure and precipitation behaviour of a TiMo microalloyed steel processed by continuous cooling. A dual-phase steel with interphase precipitation-strengthened ferrite has been successfully produced by continuous cooling. Transmission electron microscopy and atom probe tomography proved that precipitates formed during continuous cooling were nano-sized (Ti, Mo)C interphase precipitates. More importantly, the interphase precipitation-strengthened ferrite phase became harder than the bainite phase, leading to a new strategy for producing dual-phase steels. The continuous cooling process for interphase precipitation can be used for a wide range of conventional steel production lines, since there is no need for coiling operation of hot strip mills.