Dual Phase Steel Characterization for Tube Bending and Hydroforming Applications

This study examined the behaviour of dual phase steel tubes from three different strength grades undergoing rotary draw bending and pressure sequence hydroforming. It was found that the level of strain experienced by the tubes was independent of the steel grade. It was also shown that the same microstructural features that affect strength and elongation in uniaxial tensile testing affected dual phase steel tubes undergoing tube bending.;Nano indentation techniques were developed to facilitate the measurement of hardness of individual phases within dual phase steel. Three steels from different strength grades were tested. It was found that the hardness of the martensite phase followed the trend predicted by the calculated martensite carbon content.;Seven commercial dual phase steels from three different suppliers were compared. It was found that the strength of the steels was mainly dependent on martensite volume fraction, while elongation was influenced by the level of martensite banding.