Effects of titanium addition on precipitate and microstructural control in C-Mn microalloyed steels

A study was carried out on the effects of Ti in a T-lean and a Ti-modified C-Mn microalloyed steels of otherwise comparable compositions. Analyses were carried out by SEM and TEM on steel microstructure, microalloying element precipitates and on non-metallic inclusions. A theoretical support to the experimental data was obtained by thermodynamic analyses aimed at stating phase stability and composition as a function of temperature for the steels investigated. Experimental results and theoretical predictions were combined to cast light on carbide, nitride and sulphide evolution during thermal cycles associated to fabrication route of the steels.