Effect of Hot Rolling Parameters on the Microstructure and Properties of Ti Microalloyed Steel Produced by Compact Strip Production

Experimental methods, such as SEM, TEM and chemical phase analysis, were used to study the effect of hot rolling parameters on the microstructure and properties of Ti microalloyed steel produced by compact strip production.The results show that the yield strength and tensile strength of steel were 825 MPa and 895 MPa respectively when finish rolling temperature 880℃ and coiling temperature 620℃.Large amount of nanometer TiC particles existed in steel, and the precipitation strengthening effect of these particles achieved to 150 MPa.The precipitation of titanium carbides was inhibited and precipitation strengthening effect of nanometer particles reduced significantly as coiling temperature was decreased to 580℃.The change of coiling temperature had prominent effect on the precipitation of secondary phases in steels, and the grain size of steel strips was influenced by the change of rolling and coiling temperature.Comprehensive role of the two factors induced fluctuation of strength and toughness of Ti microalloyed steel.