Precipitatation Behavior of FeTiP Phase in High Strength IF Steel

The influence of chemical composition and annealing parameters on the behavior of FeTiP precipitation has been investigated. With increasing Ti content the yield strength and tensile strength were reduced, and the tendency of FeTiP precipitation became more remarkable. No FeTiP precipitate was observed and the best mechanical properties have been obtained in the steel sheet, of which the atom ratio of Ti to N is approximately equal to 1. In the temperature range of 700 to 800℃ the FeTiP precipitation could appear easily. The precipitation process was suppressed when the annealing temperature was below 600℃, and the FeTiP phase was dissolved above 900℃. The FeTiP precipitates would inhibit the migration of grain boundaries during the recrystallization in certain extent, and weaken the density of {111} fiber texture, which resulted in the reduction of r value. The relationship between composition and processing parameters, as well as their influence on the mechanical properties is discussed.