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7CrMoVTiB10-10 (T24) steel is recommended for fabrication of boiler components such as water walls, water panels or headers without post weld heat treatment (PWHT). The chemical composition of this steel and cooling conditions after welding influence the susceptibility to cracking in weld metal during and after welding. TEM investigations showed that in the as-welded microstructure mixtures of bainite and martensite were dominating. This has an important implication for technological properties.

The research was carried out on 26Mn-3Si-3Al steel having a low value of SFE. After casting, steel was forged and hot-rolled at the temperatures within the range of from 1200°C to 900. Next, the steel was cold rolled until the deformation of 66% was obtained. Upon the basis of X-ray examination and the observations of microstructures, it was found out that during cold rolling mechanical twinning and the martensitic transformation of austenite in hcp-ε martensite occurred. The crystallographic texture of the γ phase (austenite) and ε phase (martensite) was also examined.

The present research is a part of project dealing with structural aspects of ferrite and austenite co-deformation in duplex stainless steels. The examination concerned a development of ferrite and austenite microstructures, major deformation mechanisms operating in both phases and texture formation upon cold-rolling of a model duplex type steel. The investigations showed that the band-like morphology of two-phase structure formed upon processing together with specific starting textures obtained after a preliminary thermo-mechanical treatment exerted significant influence on texture and microstructure development in both constituent phases. Microstructure and texture evolution in examined duplex steel significantly differed from those in one-phase steels. These differences resulted first of all from the role of the phase boundaries acting as the barriers for dislocation movement and affecting the processes of strain localization at higher deformations.

A new high chromium martensitic steel, VM12, was recently developed for advanced coal-fired ultra-supercritical steam power plants. A very important factor in maintaining high creep resistance during service exposure is its stable microstructure, in particular high dispersion particle strengthening, which slow down the recovery and softening processes of the matrix. Quantitative characterisation of the precipitates in the VM12 steel as received condition and after creep tests up to about 30000 h at 625 °C using TEM was carried out.

Transmission electron microscopy (TEM) was used to assess the microstructural changes accompanying semisolid molding of a creep resistant Mg-5%Al-2%Sr alloy. It was revealed that the processing created thixotropic morphologies with globular solids of α-Mg, having well-developed sub-structures. The quickly-solidified liquid fraction, enriched in Al and Sr, led to the formation of increased volumes of a lamellae type Al4Sr phase, surrounding the secondary α-Mg. Traces of Mg17Al12 still existed, predominantly as irregular shape compounds located mainly in grain interiors. Both the primary solid and high melting point precipitates of Mn-Al modified with Sr, acted as nucleation substrates for secondary α-Mg grains.