Flash processing is a new heat treatment process being developed to produce steel with relatively high strength and ductility. It involves rapidly heating steel sheet or strip to a temperature in the austenite range and quenching; the entire thermal cycle takes place within 15 seconds. The resulting microstructure is fine and difficult to resolve using standard metallographic techniques. In thi...

Plastic deformations, such as those obtained by shot peening on specimen surface, are an efficient way to improve the mechanical behavior of metals. Generally, scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD) are commonly used to observe the complex microstructural evolutions, such as grain refinement and phase transformation, induced by the surface treatment. In...

The first evidence is provided for the existence of a tetragonal or slightly orthorhombic unit cell of bainitic ferrite. It supports the hypothesis that the excess carbon that persists in the ferrite, which is in contact with austenite, is a consequence of an increased solubility due to the change in symmetry from the conventional cubic unit cell. The deviations from the cubic cell are maintain...

We report an attempt at increasing the thermal stability of nanocrystalline bainite to tempering heat-treatments, by enhancing the silicon concentration of the alloy. Validation experiments have been conducted using synchrotron X-radiation during tempering heat treatment. It is found that the change in alloying successfully stabilises the austenite at elevated temperatures by retarding cementit...

The background to this bachelor thesis is an on-going project within the VINN Excellence Center Hero-m. The task in this thesis is to perform a literature survey about the martensite transformation and investigate how the resulting fraction depends on cooling below the Ms-temperature. Instead of calculating the undercooling for each of the known fractions of martensite the driving force will be...

the effects of carbon content on the dynamic and static softening mechanisms of ti microalloy steels were investigated both in ferrite and austenite regions. the results obtained showed that recrystallization rate decreased as the percentage of carbon content was increased from 0.0035 to 0.110. this is due to the ti(cn) and tic precipitates and also the free carbon content. in the ferrite regio...

The vast majority of steel weld deposits solidify under highly nonequilibrium cooling conditions. A consequence of this is the chemical segregation of substitutional alloying elements during solidification, a segregation that persists as the weld cools to ambient temperature. Solidification-induced segregation of interstitials is usually not a problem due to the ease with which they can diffuse...

Kinetic dependence of martensitic transformation and properties changes in Fe-24%Ni5%Mo alloys with different carbon content have been obtained. Internal friction method was used for the precise investigation of structural changes after austenization, during martensitic transformation at sub zero temperature and during the postheat. The influence: (i) of frequency of oscillations, (ii) rate of ...

We show that in metamagnetic shape memory alloys exhibiting a magnetostructural first order phase transition the direct transition from ferromagnetic austenite to nonmagnetic martensite is isothermal. In contrast to the direct transformation, the reverse one nonmagnetic martensite–ferromagnetic austenite is athermal, just as are athermal both direct and reverse martensitic transformations in co...

The formation of stress-induced martensite in superelastic NiTi was studied by neutron diffraction during uniaxial compressive loading and unloading. The respective phase fractions were determined as a function of the applied stresses using a Rietveld refinement with a March–Dollase texture formulation. Before loading, the specimen was fully austenitic. At the highest applied stress of 2625 MPa...