Effect of Intercritical Annealing on the Properties of Dual Phase Steel via Finite Element Method.

Dual-phase (DP) steels are becoming more and more popular for automotive applications. They offer a weight reduction with a combination of energy absorption for crash zones. Rails, reinforcements, back panels, cross members, and pillars can be given as application examples. DP steels microstructure consists of a soft ferrite with hard martensite. The martensite provides strength while the ferrite provides ductility. The strength level of DP steel is correlated with the martensite fraction in the microstructure, and the fraction of martensite can be controlled via intercritical annealing. In this work, thermodynamic analysis of St52 steel was carried out with Thermo-Calc software. A1 and A3 temperatures were determined by calculating the temperaturedependent phase fractions. Intercritical annealing temperatures were determined according to the calculated critical temperatures (A1 and A3). The intercritical annealing process was modelled by using Simheat NxT software. In this modelling and simulation study, the intercritical annealing temperature impact on the final microstructure and hardness of DP steel was investigated. [ABSTRACT FROM AUTHOR]