Effect of Mn concentration on the kinetics of strain induced precipitation in Ti microalloyed steels

The kinetics of strain induced precipitation in Ti-microalloyed steel with three levels of Mn was investigated using a two-stage interrupted compression (TSIC) test. The precipitation-time–temperature diagrams (PTT) were obtained by analyzing the softening kinetics curves of deformed austenite. Experimental results showed that the upper part of the PTT diagram for strain induced precipitation were shifted to lower temperatures and longer times as Mn concentration in steel was increased, but the retard effect of Mn on TiC precipitation weakened with decreasing testing temperature. Transmission electron microscopy (TEM) observation showed that the rate of TiC precipitation was decreased by more Mn addition at higher testing temperatures, which is in a good agreement with TSIC result. In addition, these results were discussed in terms of the effect of Mn on the solubility product of TiC in austenite, and the controlling factors of precipitation kinetics at different temperatures.