Yury Fedorovich Ivanov

Evolution of Al–19·4Si alloy surface structure after electron beam treatment and high cycle fatigue

Abstract Processing of Al–19·4Si alloy by high intensive electron beam has been carried out, and multiple increase in fatigue life of the material has been revealed. Investigations of structure and surface modified layer destruction of Al–19·4Si alloy subjected to high cycle fatigue tests to fracture have been carried out by methods of scanning electron microscopy. The factors responsible for the increase in fatigue life of Al–19·4Si alloy have been revealed and analysed.

Surface layer structure degradation of rails in prolonged operation

By methods of optical, scanning and transmission electron microscopy and microhardness measurement the transformation regularities of structure-phase states, defect substructure, fracture surface and mechanical properties of rail surface layer up to 10 mm deep in process of long-term operation (passed tonnage of gross weight 1000 mln. tons) were revealed. According to the character of fracture and level of structure imperfection the three layers were detected: surface, transition and boundary ones. It has been shown that the surface layer ~20 μm in thickness has a multiphase, submicro- and nanocrystalline structure and it contains micropores and microcracks. The increased density of bend extinction contours at 2 mm depth from the tread contact surface was noted, and it was shown that the maximum amplitude of stress fields was formed on the interphase boundary the globular cementite particle–matrix. The evaluation of stress fields was done.

Surface Modification of TiC–NiCrAl Hard Alloy by Pulsed Electron Beam

The mechanisms by which nanostructural states are realized in e-beam-irradiated TiC-NiCrAl cermet depending on the irradiation mode have been revealed. Mechanical testing and tribotesting have yielded criteria for a substantial (a factor of 1.5-3) increase in performance characteristics of the cermet alloy (micro- and nanohardness, cutting resistance, coefficient of friction, and bending resistance).

Fatigue life of silumin treated with a high-intensity pulsed electron beam

The regularities of the formation of the structure of silumin irradiated with a high-intensity electron beam in different modes are revealed using optical and scanning electron microscopy. The optimum irradiation mode that allows one to increase the fatigue life of this material by a factor of up to 3.5 is determined. The probable causes of the observed effect are investigated.

Structure of electroexplosive TiB 2 –Ni composite coatings after electron beam processing

High-intensity electron beam modification of electroexplosive TiB2–Ni composite coatings is conducted for the first time. The phase and elemental composition of the surface layer of steel Hardox 450 subjected to electroexplosive spraying (EES) of the TiB2–Ni composite coating and subsequent irradiation with a submillisecond high-intensity pulsed electron beam are studied. Electron beam processing (EBP) modes that provide the formation of dense glossy surface layers based on titanium diboride and nickel with a submicrocrystalline structure are revealed. It is shown that EBP of a layer subjected to EES conducted in a melting mode leads to the formation of a surface layer with homogeneous structure and concentration.

Structural and phase states in high-quality rail

The structural and phase states and dislocational substructure in high-quality bulk-quenched rail are assessed quantitatively by transmission electron diffraction microscopy. On the basis of the morphological features, the following structural components of the rail steel are identified: plate pearlite (68%); mixed ferrite–carbide grains (28%); and structure-free ferrite grains (4%). Analysis of the flexural extinction contours shows that the stress concentrators in the steel are the boundaries between cementite plates within the pearlite grains; the boundaries between the pearlite grains and the ferrite grains; and the boundaries between globular particles of secondary phase and the ferrite matrix. The particle–matrix boundaries are the most significant stress concentrators and may be regarded as the primary sites of crack formation.

Formation of the Increased Wear-Resistant Properties of Hardox 450 Steel by Deposited Coatings

The structure-phase conditions formed during the deposition of surface coatings on Hardox 450 steel by the wire comprising C, V, Cr, Nb, W were examined by the methods of X- ray phase analysis and transmission electron diffraction microscopy. It was established that after the hardened layer was deposited, the wear-resistance increased 153 times and the coefficient of friction in the material decreased 2.5 times. It was concluded that the increased properties of the surface coating were due to the formation of martensitic structure and the occurrence of high volume fraction of carbide phase inclusions.