Study on Precipitates of V-N Microalloyed CSP Steel

A Gleeble 1500D simulation machine is applied to simulate the production process of V-N microalloyed CSP steel strip in laboratory.The results show that almost all Ti of the steel precipitates as TiN in the incipient period of continuous casting.With the temperature decreasing of casting slab,V starts to precipitate with TiN as nucleation core or nucleate and grow up independently.After soaking,most of the independently-nucleated V(C,N) tends to dissolve,and the undissolved V(C,N) starts to grow up,meanwhile the V in (Ti,V)(C,N) dissolve partially and the V content in these particles reduces.During the tandem rolling process,the V(C,N) precipitates from the steel again,which plays a role of preventing austenite grain from growing up and facilitates ferrite nucleation.This increases austenite/ferrite transformation ratio and fines ferrite grain size eventually.