The shape memory effect exhibited by Fe-Mn-Si based alloys is due to the y(f.c.c.)-e(h.c.p.) martensitic transformation. The martensitic transformation induced by traction at room temperature in a Fe16Mn-9Cr-5Si-4Ni (%mass) is here studied by optical microscopy, scanning electron microscopy, transmission electron microscopy and scanning tunnelling microscopy. The martensitic microstructure and ...

Coarse crystals of martensite can form by the coalescence of thin individual platelets of martensite under appropriate circumstances. Although these coarse grains are essentially single crystals, there exist significant orientation gradients across their dimensions. It is demonstrated that these gradients arise because of the plasticity induced in austenite due to the transformation strain asso...

The features of martensite transformation in Fe (31 32)% Ni melt-quenched alloys are considered. The meltquenching was realized by spinning technique with variable parameters. The influence of the melt-quenching on structural and kinetics transformation parameters is revealed. In particular Ms point is shown to decrease but volume percentage of athermal martensite is found to be invariable with...

The influence of nitrogen (0 to 0.27 wtYo) on martensite formation in an experimental low-nickel stainless-steel alloy (Fe-17Cr-7Mn-4Ni) has been investigated. The alloys containing 0.1 wtYo or more nitrogen are fully austenitic at room temperature; those containing less nitrogen consist of a mixture of austenite, martensite and S-ferrite. The alloys containing less than 0.2 wtYo nitrogen are m...

The purpose of this study was to evaluate the effect of heat treatment on the transformation temperatures of K3, K3XF and MTwo endodontic files. DSC was used to investigate the domains of transformation temperatures and how the transformation temperatures vary along the file. The files were analysed as received and subjected to heat treatment. X-ray diffraction analysis was also used to investi...

Utilizing electrical resistance measurements in combination with strain observations on single crystals, it was possible to distinguish the austenite to martensite transformation from the detwinning of the martensite behavior during deformation of NiTiCu shape memory alloys. It was found that the electrical resistance change associated with the detwinning of the martensite variants was as high ...

A generalized phase transformation kinetics model is used to understand the martensite to austenite transformation in a cold-rolled and annealed metastable AISI 301LN ultrafine-grained austenitic stainless steel. The model shows that the presence of interstitial nitrogen and heavy cold-rolling is important to promote fast transformation kinetics, through rapid nitrogen-diffusion and austenite n...

Many studies monitoring the formation of martensite during the tensile deformation of austenite report data which are, in principle, affected by both the applied stress and the resulting plastic strain. It is not clear in these circumstances whether the transformation is stress induced (i.e. the stress provides a mechanical driving force) or whether the generation of defects during deformation ...

We study the behavior of crystals that undergo martensitic transformations. On cooling, the high-temperature phase (austenite) transforms to the martensite phase changing its crystalline symmetry. The lower crystalline symmetry of the martensite gives rise to several variants of martensite. Each variant has an associated transformation strain. These variants accommodate themselves (according to...

Article history: Received: 23.12.2013. Received in revised form: 15.01.2014. Accepted: 15.01.2014. Subcritical austenite reverse transformation quenching was used to improve the mechanical properties of 30CrMnSi steel, and the microstructure and mechanical properties of the samples were analyzed by subcritical austenite reverse transformation quenching. Experimental results show that subcritica...