Martensite phase stress and the strengthening mechanism in TRIP steel by neutron diffraction

Abstract

Two TRIP-aided multiphase steels with different carbon contents (0.2 and 0.4 mass%) were analyzed in situ during tensile deformation by time-of-flight neutron diffraction to clarify the deformation induced martensitic transformation behavior and its role on the strengthening mechanism. The difference in the carbon content affected mainly the difference in the phase fractions before deformation, where the higher carbon content increased the phase fraction of retained austenite (γ). However, the changes in the relative fraction of martensitic transformation with respect to the applied strain were found to be similar in both steels since the carbon concentrations in γ were similar regardless of different carbon contents. The phase stress of martensite was found much larger than that of γ or bainitic ferrite since the martensite was generated at the beginning of plastic deformation. Stress contributions to the flow stress were evaluated by multiplying the phase stresses and their phase fractions. The stress contribution from martensite was observed increasing during plastic deformation while that from bainitic ferrite hardly changing and that from γ decreasing.

The influence of temperature on deformation-induced martensitic transformation in 301 stainless steel

“…Harjo et al 45 and Moat et al 4 , is deemed not appropriate in this case. This is because the sample and instrument design render the gauge volume of the instrument not fully filled.…”

Developing an interatomic potential for martensitic phase transformations in zirconium by machine learning

“…The transformation involves interesting mechanical properties, from strengthening to superelasticity, and shape memory effects. [1][2][3][4] Therefore, understanding the atomistic mechanisms underlying the MT plays an important role in achieving the desired material properties. The development of the microstructure arising from these transformations is strongly governed by the crystallographic symmetry or geometry of the phases; 5,6 hence, atomistic computer simulations can be especially valuable to gain insight into the details of the phase transformation kinetics.…”

Tensile Deformation of Ultrafine-Grained Fe-Mn-Al-Ni-C Alloy Studied by In Situ Synchrotron Radiation X-ray Diffraction

“…These results, along with the observations on the deformed microstructures of B2 phase in similar alloys [22,23], suggested that the B2 phase in the present alloy was essentially not brittle and was capable for plastic deformation. The elastic stress in each constituent phase, i.e., the so-called phase stress [37,40,41], can be evaluated from the phase strains using Hook's law and Poisson's ratios. A simplified estimation is often used, under the assumption that the phase strain can be represented by the lattice strain of certain (hkl) planes, for evaluating the phase stress when the strain in the transverse direction is not available [41]:…”

“…The elastic stress in each constituent phase, i.e., the so-called phase stress [37,40,41], can be evaluated from the phase strains using Hook's law and Poisson's ratios. A simplified estimation is often used, under the assumption that the phase strain can be represented by the lattice strain of certain (hkl) planes, for evaluating the phase stress when the strain in the transverse direction is not available [41]:…”