Austenite carbon enrichment and decomposition during quenching and tempering of high silicon high carbon bearing steel

The addition of Si to steels is a well stablished method to delay cementite precipitation, allowing for carbon partitioning from martensite to retained austenite during tempering. It has been argued that carbon enrichment and stabilization of austenite leads to increased ductility and toughness. This has been the main motivation for the...

Self healing of creep-induced damage in Fe-3Au-4W by multiple healing agents studied by synchrotron X-ray nano-tomography

Constant stress creep experiments at 550 °C were performed on a high-purity Fe-3Au-4W (wt.%) ternary alloy with about 1 at.% supersaturation for Au and W in order to study self healing of grain-boundary cavities by both Au-rich and W-rich precipitates. Using synchrotron X-ray nano-tomography, the development of the creep cavities and the...

An electromagnetic physics constructor for low energy polarised X-/gamma ray transport in Geant4

The production, application, and/or measurement of polarised X-/gamma rays are key to the fields of synchrotron science and X-/gamma-ray astronomy. The design, development and optimisation of experimental equipment utilised in these fields typically relies on the use of Monte Carlo radiation transport modelling toolkits such as Geant4. In...

Solid state phase transformations in steels: a neutron and synchrotron radiation study

Solid-state phase transformations in steels cover a broad range of aspects. The underlying physics behind these phase transformations usually include nucleation, diffusion, lattice reconstruction and interactions between solutes and grain boundaries and interfaces. These features and the fact that the events take place at high temperatures, in...

Self healing of creep damage in iron-based alloys by supersaturated tungsten

When metals are mechanically loaded at elevated temperatures for extended periods of time, creep damage will occur in the form of cavities at grain boundaries. In the present experiments it is demonstrated that in binary iron-tungsten alloys creep damage can be self healed by selective precipitation of a W-rich phase inside these cavities. Using...

Jupiter's radiation belts at 13.8 GHz

The Jupiter flyby of Cassini in 2001 allowed to study the gas giant in detail. Jupiter’s inner magnetosphere is populated by high energy particles, causing an intense radiation observable throughout the microwave regime. The re-calibration of the Cassini RADAR instrument has allowed for constraining the energy distribution of the electron...

High-resolution X-ray diffraction investigation on the evolution of the substructure of individual austenite grains in TRIP steels during tensile deformation

The martensitic transformation behaviour of the metastable austenite phase in low-alloyed transformation-induced plasticity (TRIP) steels has been studied in situ using high-energy X-ray diffraction during deformation. The austenite stability during tensile deformation has been evaluated at different length scales. A powder diffraction analysis...

Position-dependent shear-induced austenite– martensite transformation in double-notched TRIP and dual-phase steel samples

While earlier studies on transformation-induced-plasticity (TRIP) steels focused on the determination of the austenite-to-martensite decomposition in uniform deformation or thermal fields, the current research focuses on the determination of the local retained austenite-to-martensite transformation behaviour in an inhomogeneous yet carefully...

Austenite stability in TRIP steels studied by synchrotron radiation

TRIP steel is a material providing great mechanical properties. Such steels show a good balance between high-strength and ductility, not only as a result of the fine microstructure, but also because of the well-known TRIP effect. The Transformation Induced-Plasticity (TRIP) phenomenon is the transformation of the soft metastable austenite phase...

In-situ characterization of grain nucleation and coarsening in metallic microstructures using synchrotron radiation

The research described in this thesis encompasses fields of 3DXRD, phase transformations and grain coarsening in iron alloys.

Austenite formation in C-Mn steel

The production process of almost all modern steels involves austenitization formation of the austenite phase upon continuous heating. Many of the microstructural features and properties that are obtained upon subsequent cooling are to a large extend determined by the evolution of the microstructure and chemical inhomogeneities during...