The trapping of carbon by titanium in ferritic stainless steels with low interstitial contents depends on the presence of other non metallic elements such as phosphorus. The decrease of phosphorus content in the steels promotes the segregation of carbon at the grain boundaries and prevents the formation of the titanium carbonitrides. In fact, the formation of these precipitates depends on the quantity of remaining carbon in the matrix after the segregation of this element at the grain boundaries. Thus, this quantity could be sufficient to allow the formation of Ti(C, N) compounds by reduction of their solubility as the tempering temperature is decreased.