B.B. Ovechkin

Fatigue life enhancement by irradiation of 12Cr1MoV steel with a Zr+ ion beam. Mesoscale deformation and fracture

The structure and properties of 12Cr1MoV steel irradiated with a zirconium ion beam were studied by optical microscopy, scanning electron microscopy, and micro- and nanoindentation. It is shown that the modification covers the entire cross-section of the irradiated specimens to a depth of 1 mm. The data on irradiation-induced structural changes are used to interpret the changes in mechanical properties of the irradiated specimens under static and cyclic loading. Particular attention is given to analysis of strain estimation by the digital image correlation method.

Increasing the fatigue life of 12Cr1MoV steel by surface nanostructuring with a Zr+ ion beam. Structure, properties, and fracture pattern

The paper presents the results of static and cyclic tensile tests and alternate cyclic bending tests of 12Cr1MoV specimens in the initial state and after surface nanostructuring with a Zr+ ion beam. Examination by optical and scanning electron microscopy and interference profilometry revealed differences in the formation of the deformation relief and in the character of cracking of the modified surface layer. The changes occurring in the modified surface layer were estimated by nanoindentation, X-ray analysis, and fractography. The nanostructure formed in the treated surface layer was analyzed by transmission electron microscopy. The difference in deformation is interpreted using the multiple cracking concept. The effect of substantial enhancement of fatigue strength is associated with retarded plastic deformation and fatigue crack propagation in the modified surface layer.

Scientific basis for cold brittleness of structural BCC steels and their structural degradation at below zero temperatures

The paper considers the physics of cold brittleness of structural bcc steels and methods of reducing the ductile-brittle fracture temperature. A complex study was performed to examine the degradation of structural phase state of pipe steel 09Mn2Si from the main gas pipeline of Yakutia after long-term (over 3 0 years) operation. Important regularities of degradation of pearlite colonies with carbide precipitation on ferrite grain boundaries were revealed. This phenomenon is associated with brittle fracture of gas pipelines. It is shown that the low-temperature kinetic processes in main pipelines which define the degradation of their structure and properties are related to interstitial athermal structural states in the zones of local crystal structure curvature. This is a fundamentally new, as yet unknown, mechanism. Pipe steels in warm rolling acquire a longitudinal textured band structure with alternating bands of initial ferrite grains and bands of fine grains with carbide precipitates formed during lamellar pearlite degradation. This type of structure allows for a shift of ductile-brittle transition temperature down to -80°C and ductility δ = 22% at this temperature. The production of high-curvature vortex structure in pipe steel surface layers results in a 3.5-fold increase in their service life.

Effect of vacuum arc ion beam treatment on the structure and mechanical properties of 30CrMnSiNi2A steel

The paper reports on a study of the structure and mechanical properties of 30CrMnSiNi2A high-strength steel irradiated with a Zr+ ion beam. The effect of irradiation on the steel was assessed by optical, transmission, and scanning electron microscopy as well as by X-ray di ITraction analysis of its irradiated and non-irradiated specimens 1 mm thick under static and cyclic tension, showing an increase in the fatigue life of the steel after irradiation. The deformation behavior and the mechanical properties of the specimens were compared, and the factors responsible for the increase in fatigue life were analyzed.

Influence of High-Intensity Zr Ion-Beam Treatment on Deformation and Fracture of 12Cr1MoV Steel under Static, Cyclic and Dynamic Loadings

The structure of the heat resistant 12Cr1MoV steel modified by Zr+ ion beam treatment was investigated by optical, scanning electron and transmission electron microscopy as well as X-ray diffraction methods. It was shown that the modification occurs over the entire cross section of the irradiated specimen with thickness of 1 mm. Changes in mechanical properties under static, cyclic and dynamic loading of the specimens after the treatment are interpreted in term of structural modifications.

Polyfunctional Coatings on the Basis of Powder Paints Electrostatically Sprayed from the Composite Mixtures Treated in Planetary Ball Mill

The comparative analysis of the structure and properties of composite coatings deposited by electrostatic spraying of nine powder mixtures based on polyester powder paint (PPP), epoxy powder paint (EPP), polyurethane varnish (PUV) with micron size fillers in the form of carbon black (CB), colloidal graphite (CG) and Cr17Ni2 steel have been carried out. The powder mixtures were pre-treated in a planetary ball mill (PBM) to input the maximum amount of functionalizing particles in the coatings. The designed coatings besides carrying out conventional protective (anti-corrosion) functions might be used for removing static electricity and shielding electromagnetic radiation.

Influence of Zr+ Ion Beam Irradiation on Structure and Fatigue Durabilityof 12Cr1MoV Steel

Cyclic tension and bending tests of heat-resistant 12Cr1MoV steel specimens in as received state as well as after Zr+ ion beam irradiation were carried out. The differences in patterns of strain induced relief formation, as well cracking of thin modified surface layer were observed and analyzed by means of optical microscopy and interference profilometry. Changes to take place in subsurface layer of 150 μm thick were characterized by means of microindentation, metallography and scanning electron microscopy. It is shown that mechanical properties of irradiated specimens are mostly influenced due to thermal treatment to take place during irradiation rather than formation of a 2 μm thin surface layer doped with Zr. The differences in deformation behavior are interpreted in terms of physical mesomechanics concepts.

An Application of Spark Plasma Sintering for Compaction of Refractory Oxides and Nitrides

The results of investigation of physical and mechanical properties of ceramic materials manufactured by compaction of alumina, zirconia, and aluminum oxynitride powders using spark plasma sintering (SPS) are presented. It is found out that the ceramics thus produced exhibit improved density and microhardness compared to the materials sintered at high temperature in a resistance furnace.

Zr+ Ion-Beam Surface Treatment of 30CrMnSiNi2 Steel for Improving its Fatigue Durability

The structure of modified surface layer the high-strength 30CrMnSiNi2 steel was investigated by optical, scanning electron and transmission electron microscopy as well as X-ray diffraction methods. The tests on static and cyclic tension were performed for 30CrMnSiNi2 steel specimens in as supplied state and after nanostructuring surface layer by Zr+ ion beam. Differences of the specimen deformation behavior and changes of their mechanical properties are analyzed. The reason for fatigue life increase of the samples after the treatment is discussed.

Effect of ultrasonic treatment on mechanical behaviour of ferrite-martensite steel

The effect of ultrasonic treatment on the feature of plastic deformation and mechanical properties of ferrite-martensite steel with various structural states were investigated. To change the initial structural states the specimens were subjected to heat hardening, ageing, cold rolling and/or nitration. It is shown that ultrasonic treatment forms within the surface layer submicrocrystalline structure. As a result, the microscale level of deformation is suppressed. Ultrasonic impact of untreated and/or hardened and aged specimens rises the strength of the materials. Deformation of the specimens subjected to cold rolling with subsequent ultrasonic treatment is strongly localised at its ends. It results in drastic reduction of material strength.