Effect of the martensite distribution on the strain hardening and ductile fracture behaviors in dual-phase steel

Kyosun Park, Masato Nishiyama, Nobuo Nakada, Toshihiro Tsuchiyama, Setsuo Takaki

    Research output: Contribution to journalArticlepeer-review

    158 Citations (Scopus)

    Abstract

    In order to clarify the effects of the martensite distribution on the mechanical properties of low-carbon dual-phase steel, four types of dual-phase steel with different ferrite grain sizes and martensite distributions were prepared using a thermomechanical treatment. The tensile properties of these steels were investigated; in particular, the strain hardening and the ductile fracture behaviors were discussed in terms of the strain partitioning between the ferrite and martensite and the formation and growth of micro-voids, respectively. When the martensite grains surround the ferrite grains and form a chain-like networked structure, the strain hardenability is greatly improved without a significant loss of elongation, while the necking deformability is considerably reduced. A digital-image correlation analysis revealed that the tensile strain in the martensite region in the chain-like networked dual-phase structure is markedly increased during tensile deformation, which leads to an improvement in the strain hardenability. On the other hand, the joint part of the martensite grains in the structure acts as a preferential formation site for micro-voids. The number density of the micro-voids rapidly increases with increasing tensile strain, which would cause the lower necking deformability.

    Original languageEnglish
    Pages (from-to)135-141
    Number of pages7
    JournalMaterials Science and Engineering A
    Volume604
    DOIs
    Publication statusPublished - May 16 2014

    All Science Journal Classification (ASJC) codes

    • Materials Science(all)
    • Condensed Matter Physics
    • Mechanics of Materials
    • Mechanical Engineering

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