Metal Science and Heat Treatment

Stavrev, D.

doi: 10.1023/B:MSAT.0000019191.82343.b5pmid: N/A

The effect of concentrated energy fluxes (CEF) on graphite inclusions and carbides in steel and cast iron is investigated. Experimental data are used to show that the carbides and the graphite can be treated as metastable phases. Diffraction analysis of gray cast iron and steel Kh12 is used to show that their structure acquires a nonequilibrium “baikovit” eutectic due to plasma-arc CEF followed by heat treatment. The effect of tempering on the changes in the nonequilibrium structure is studied.

Kolotushkin, V.; Kondrat'ev, V.; Laushkin, A.; Rechitskii, V.

doi: 10.1023/B:MSAT.0000019192.49582.25pmid: N/A

The methods of electron microscopy, metallography, and determination of impact toughness and resistivity are used to investigate the structural and phase stability of nickel-chromium alloys after aging at 350, 400, and 450°C for up to 40,000 h. The chromium content is shown to be correlated with the susceptibility of the alloys to ordering. It is established that the alloy with about 41 wt.% Cr has the highest stability of the structure and properties in the studied temperature range.

Qinghua, Zou; Jinping, Wu; Hujian,

doi: 10.1023/B:MSAT.0000019193.27879.3bpmid: N/A

A new type of dynamic phase diagrams for spring steels of the Si2Mn type is presented and a formula is suggested for describing the lever principle as applied to such diagrams. The structure and chemical composition of the studied steels are analyzed.

Murav'ev, V.; Yakimov, A.; Chernyshev, A.

doi: 10.1023/B:MSAT.0000019194.64623.48pmid: N/A

The effects of forging, stamping, and different kinds of pressing, rolling, fuse welding, and electrocontact heating in an air medium on the structure and properties of titanium alloy VT20 are considered. It is shown that the traditional methods of plastic deformation, welding, and heat treatment of structures from alloy VT20 provide high parameters of strength and ductility in them. The properties of preforms from alloy VT20 are improved considerably after final die forging in the temperature range of the α → β phase transformation. Electrocontact heating in the range of the α → β phase transformation and subsequent cooling in metallic die in the forming process fully realizes the strength and ductility of sheet preforms from titanium alloy VT20.

Berdin, V.; Karavaeva, M.; Syutina, L.

doi: 10.1023/B:MSAT.0000019195.58304.6epmid: N/A

Formation of crystallographic texture due to plastic deformation of cylindrical specimens of VT9 titanium alloy by uniaxial stretching, twisting, and simultaneous twisting and stretching is considered under the conditions of superplasticity. The dependence of the kind of loading on the type of texture formed and the grain size is considered. The uniformity of the variation of the texture in the cross section of specimens is studied as a function of the loading type.

Blednova, Zh.; Budrevich, D.; Makhutov, N.; Chaevskii, M.

doi: 10.1023/B:MSAT.0000019196.25544.f3pmid: N/A

The technological aspects of argon-arc facing of an alloy with the shape memory effect (nitinol) on the surface of steels 45 and 40Kh are considered. Results obtained in working out the facing process and structural and metallographic studies of the compositions are presented. The method of multifractal parametrization is used for determining the size of the transition zone and the stability of the structure of the faced layer. Possible applications of materials whose surface is modified by an alloy with the shape memory effect are considered.

Simonov, V.; Skibin, A.; Skibina, G.

doi: 10.1023/B:MSAT.0000019197.72344.d2pmid: N/A

A mathematical model is developed for simulating the formation and growth of phases in the diffusion of aluminum through the nickel matrix of high-temperature alloys. The kinetic laws of diffusion processes in multiphase coatings deposited from a gaseous phase by the method of circulation are determined. The suggested mathematical model is tested experimentally.

Sereda, B.; Palekhova, I.

doi: 10.1023/B:MSAT.0000019198.18429.2bpmid: N/A

A vapor-phase SHS method for depositing complex titanium coatings in the thermal self-ignition mode on iron and carbon steels of grades 20, 45, and U8 is considered. A tentative scheme for formation of the coatings is suggested. The thickness of the coating is shown experimentally to depend on the parameters of the process (the temperature and time of the isothermal hold). Results of microscopic and x-ray diffraction analysis of the structure and the phase composition and of measurement of the microhardness are presented. The effect of the composition of reaction mixtures on the density and porosity of the coatings is analyzed. Comparative data on the corrosion resistance of specimens with titanium- and silicon-bearing SHS coatings and similar coatings obtained by conventional chemicothermal treatment are presented.

Shatsov, A.

doi: 10.1023/B:MSAT.0000019199.97756.3bpmid: N/A

Porosity has a considerable effect on the mechanical properties of powder materials. The considered approaches make it possible to relate the mechanical properties of powder materials with the characteristics of the porous structure. The models are checked for specimens of special-purity iron because of the minimum effect of impurities.

Frishberg, I.; Zolotukhina, L.; Kishkoparov, N.; Baturina, O.; Kharlamov, V.; Zhidovinova, S.

doi: 10.1023/B:MSAT.0000019200.20009.72pmid: N/A

The effect of ultrafine powders of copper alloys in lubrication on friction surfaces is considered. It is shown that friction is accompanied by structural changes in the copper alloys with formation of intermetallic compounds and deposition of copper on the mating surfaces. The amount of copper depends on the chemical composition of the ultrafine alloys and microdistortions of their crystal lattices.