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The effect of solid-solution treatment on the microstructure and tensile properties of high-nitrogen and nitrogen-free high entropy alloys (FeMnCrNiCo and FeMnCrNiCoN, N=0.36 mass.% and N=0.44 mass.%) has been investigated. It has been established that all materials under study possess an fcc crystal lattice, the lattice parameter of which increases with increasing nitrogen content. In comparison with the cast state, which is characterized by a coarse-grained dendritic microstructure, the alloys after solid-solution treatment show a more homogeneous microstructure. Solid-solution treatment does not significantly affect the mechanical characteristics of the alloys and their fracture micromechanisms.

High-nitrogen austenitic steels are perspective materials for an electron-beam welding and for producing of wear-resistant coatings, which can be used for application in aggressive atmospheres. The tensile behavior and fracture mechanism of high-nitrogen austenitic steel Fe-20Cr-22Mn-1.5V-0.2C-0.6N (in wt.%) after electrochemical hydrogen charging for 2, 10 and 40 hours have been investigated. Hydrogenation of steel provides a loss of yield strength, uniform elongation and tensile strength. The degradation of tensile properties becomes stronger with increase in charging duration - it occurs more intensive in specimens hydrogenated for 40 hours as compared to ones charged for 2-10 hours. Fracture analysis reveals a hydrogen-induced formation of brittle surface layers up to 6 [mu]m thick after 40 hours of saturation. Hydrogenation changes fracture mode of steel from mixed intergranular-transgranular to mainly transgranular one.

The ultrafine-grained structures produced by cold (20 ?C) and warm (450 ?C) high- pressure torsion in low-carbon steel were studied using transmission electron microscopy and X-ray analysis. After cold high-pressure torsion, the size of fragments is smaller (100 nm) and structure is more homogeneous in comparison with warm deformation (120 nm). As a result of high-pressure torsion, the microhardness of steel investigated has been increased up to 600 HV and 570 HV after cold and warm deformation respectively.

A study of strain localization under compression of Hadfield steel single crystals at room temperature was done by light and transmission electron microscopy. At

Hadfield steel single crystals have been deformed by high pressure torsion at room temperature (P=5GPa) for 1, 2, 3 revolutions. The resulting microstructure has been studied by means of transmission electron microscopy (TEM) and X-ray analysis. The size of fragments decreases with increasing number of revolutions due to interaction of slip dislocations, microbands and thin twins. As a result of severe plastic deformation, the microhardness of the Hadfield steel has been increased, and a portion of , α' martensite has been found.