Effects of rolling and cooling process on mechanical properties and microstructure of 600 MPa microalloyed dual-phase steel produced by compact strip production

Abstract

The application of advanced high-strength steels (AHSS) has been growing rapidly in the automotive industry because of their high strength, good formability, weight reduction potential, and energy savings (Jun, 2013; Maciej, 2014). In particular, dual-phase (DP) steels, which exhibit excellent mechanical properties such as high strength, low yield ratio, high work hardening rate, continuous yielding, and good formability, have received more attention (Yousef, 2014;Mukherjee, 2009). DP steel is composed of a soft ferrite matrix, which imparts good elongation, mixed with hard martensite islands, which impart high strength (Dulal, 2014;Ramazani, 2013). This microstructure leads to high strength and excellent ductility compared to conventional low-carbon and high-strength low-alloy steels. In conventional processing of hot-rolled DP steel, elements such as silicon, chromium, and molybdenum are added in order to produce ferrite and martensite phases after hot working, cooling, and coiling. However, there are some problems such as the high costs of alloying elements and the poor fatigue properties of steels produced by conventional