The precipitated phase particles in ferrite-martensite dual phase steel(0.08C
0.22Si
1.02Mn
0.02Nb
0.013Ti
0.034Al)rolled by φ450 mill with control rolling and cooling process in laboratory has been studied by using carbon extraction-replica technique.Results showed that there was(Nb
Ti)(CN)precipitates with size being doz- ens nm at 1200 ℃; with energy dispersive X-ray spectrometer analysis
the Nb content in smaller particles was higher than Ti content of which the shape was irregular
and in large particle of which the shape was rectangle
main content was Ti with minor Nb; and in steel by control rolling and cooling
the(Nb
Ti)(CN)was interstitial precipitated phase and mainly precipitated at grain-boundary.