Observation of fracture characteristics and fine structure of dual-phase steel

Abstract

This paper studies the fracture characteristics and fine structure of dual-phase steel. Repeated corrosion polishing method was used to prepare samples, and a scanning electron microscope was used to observe the cracking phase and crack propagation path of cleavage fracture of duplex steel, and the fracture mode of duplex steel was obtained. The film was thinned by double jet and ion cleaning, and the fine structure of martensite islands and ferrite was observed under a transmission electron microscope. The results point out that the fine structure of martensite islands is related to the intercritical annealing temperature. At lower intercritical annealing temperatures, the substructure of martensite islands is dominated by twinned martensite, but the size of this twinned martensite is Configuration is less common among quenched steels with the same carbon content. As the intercritical annealing temperature increases, the amount of lath martensite increases; there are high-density dislocations induced by martensite transformation in the ferrite, and sometimes a cellular structure is formed.