Role of recrystallization and pearlite dissolution in industrial processing of DP590 steels

Abstract

Dual-phase (DP) steels derive their perfect blend of properties via the hard second phase, namely martensite or bainite in a softer ferrite matrix. The key to refine the mechanical properties of DP steels rests on optimizing and tailoring the distribution and size of the hard second phase present in the ferrite matrix. There can be several combinations of processing routes depending on the governing mechanisms, such as recrystallization, pearlite dissolution, phase transformation, etc., which can affect the morphology and distribution of martensite phase present in DP microstructures. All these mechanisms are invoked at various stages of annealing process cycle. In the present study, experimental simulation of various annealing parameters was carried out on a cold-rolled steel using a custom designed annealing simulator. The evolution of microstructure was studied by field emission scanning electron microscope. The evolving microstructures were correlated with governing mechanisms of recrystallization, pearlite dissolution, and phase transformation. Through these simulations, it was possible to tailor the microstructure and consequently improve the tensile properties of the DP steel.