Isolating contribution of individual phases during deformation of high strength-high toughness multi-phase pipeline steel

摘要

An innovative approach to fundamentally understand the contribution of individual phases in governing deformation and collapse behavior of high strength-high toughness combination microalloyed multiphase steel is elucidated. The study indicates that slip and local crystal rotation of ferrite and the rotation of bainite are the primary mechanisms that contribute to the deformation of multi-phase steel. Stress concentration was observed at ferrite-bainite and ferrite-ferrite interface and also within the bainite phase, which contributed to the rotation of bainite and nucleation of voids. Different types of voids formed within different phases and phase boundary, which also lead to different fracture morphologies.