Microscopic deformation behaviour of martensitic–ferritic dual-phase steels

Micromechanical modeling of dual phase steels

“…respectively. AU three models show the heterogeneous distribution of strain, which agrees with experimental observations of Shen et al (1986) and Rashid and Cprek (1978). Although the amount of plastic strain in the martensite is quite small « 8%), the effect on the overall material response is significant.…”

“…Bag et al (1999) reported that the increase in strength with v'll only extends up to v'll ~ 55% after which a reduction in strength is observed. The same was observed by Byun and Kim (1993) but at a different value of VIII ' Shen, Lei and Liu (1986) have observed this as weIl without specifying the value of VIII at which this takes place. Balliger and Gladman (1981) have reported a nonlinear increase of tensile strength with V m without commenting on the non-linearity.…”

“…At the microstructural scale, the ferrite phase experiences large plastic strains especially at the ferrite-martensite interface, which is reported experimentally by Shen et al (1986) and Rashid and Cprek (1978).…”

“…As mentioned earlier, Shen et al (1986) and Rashid and Cprek (1978) have shown experimentally, using scanning electron microscopic micrographs, that the martensite particles deform after the ferrite matrix is excessively deformed. Shen et al (1986) have also shown using a scanning electron microscopy equipped with a straining stage that at low V m only the ferrite matrix deforms with no measurable strain occurring in the martensite particles. Very small strains in the peripheral are as of martensite islands were reported using an interferential microscope.…”

“…The difference is thought to be due to different alloying and morphology used in each investigation. Shen, Lei and Liu (1986) have shown, using a scanning electron microscope equipped with a tensile straining stage, that the distribution of the strains between the ferrite and martensite phases, as well as among the different grains of each phase was observed to be inhomogeneous. They observed that the ferrite phase deformed immediately and at a much more rapid rate than the delayed deformation of the martensite.…”