Thermodynamically consistent, three-dimensional (3D) phase field approach (PFA) for coupled multivariant martensitic transformations (PTs), including cyclic PTs, variant– variant transformations (i.e., twinning), and dislocation evolution is developed at large strains. One of our key points is in the justification of the multiplicative decomposition of the deformation gradient into elastic, tra...

The solidification process in a weld pool has been shown to have a considerable influence upon the properties of the resultant weld. It influences the development of microstructure (Edvardsson et al., 1976), and determines the distribution of alloying elements, and hence the homogeneity of the weld. Previous work on the cooling behaviour of welds (Garland and Kirkwood, 1974; Svensson et al., 19...

The effects of the presence of the R-phase in a near-equiatomic NiTi alloy on the mechanical responses of an endodontic instrument were studied by using finite element analysis. The input data for the constitutive model in the simulation were obtained by tensile testing of three NiTi wires: superelastic austenite NiTi, austenite + R-phase NiTi, and fully R-phased NiTi. The wires were also chara...

The effect of austenite grain size on the evolution of the bainite transformation in steels is not yet certain in spite of many investigations.1–7 Barford and Owen1 reported that the reaction rate was accelerated by decreasing the grain size, because of an increase in the number density of grain boundary nucleation sites. Umemoto et al.2 reported similar results and proposed an equation that de...

Neutron diffraction spectra were obtained during various stages of a reversible stress-induced austenite to martensite phase transformation in superelastic NiTi. This was accomplished by neutron diffraction measurements on bulk polycrystalline NiTi samples simultaneously subjected to mechanical loading. Analysis of the data was carried out using individual lattice plane ~hkl! reflections as wel...

The pinning effect of cerium inclusions in the austenite grain growth of SS400 steel at 1300 ◦C is investigated by using a semi-empirical-simulation. Firstly, steel samples containing cerium inclusions are prepared; then the properties of inclusions are determined using SEM. In situ observation of austenite grain growth is performed by LSCM, to determine the fitting parameters of the model such...

The effect of plastic deformation on the transformation of austenite to acicular ferrite in a Fe /Mn /Si /C alloy steel containing non-metallic inclusions was investigated. The transformation to acicular ferrite is retarded and the final fraction of acicular ferrite is reduced in plastically deformed austenite, which is a characteristic of a displacive transformation mechanism. The increase in ...

An investigation into influence of the austenitising temperature and the austenite deformation temperature on Nb precipitation and recrystallisation kinetics was carried out for a steel containing 0.081C-0.021Ti-0.064Nb (wt. %). The austenite grain structure was correlated to the dispersive properties of Nb atom clustering and precipitation. Irrespective of the austenitising temperature, deform...

Several experimental techniques are used for phase identification and microstructure characterization of austempered vermicular cast irons (XRD, SEM, TEM and Mössbauer spectroscopy). Acicular structures were found to be composed by ferrite and austenite with average sizes compatible with those reported for bainitic ferrite in steels. An assessment of the free energy change involved in the auste...

The stabilization of retained austenite was studied via a two-step cooling procedure. Alloys with M , temperatures below 0 OC were used. It was found that the martensitic transformation starting temperature, M,, was lowered to M,' during the second step of cooling. With increasing the amount of previously formed martensite, the difference in the transformation starting temperatures, AM, (= M,M,...