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Kipelova A.,Belgorod State University | Kaibyshev R.,Belgorod State University | Skorobogatykh V.,Central Research Institute for Machine Building Technology | Schenkova I.,Central Research Institute for Machine Building Technology
Journal of Physics: Conference Series | Year: 2010

The effect of tempering temperature on mechanical properties of an E911+3%Co creep resistant steel was investigated. The mechanical tensile tests were carried out at temperatures from 298 to 1073 K and at strain rates varying from 2.1 × 10-5 s-1 to 2.1 × 10 -1s-1. The Portevin-Le Chatelier (PLC) effect was found in the temperature range of 473 to 623 K. Various attributes of dynamic strain aging (DSA) like serrated flow with an acoustic emission were observed. With increasing temperature the ultimate tensile strength (UTS) and the yield strength (YS) increased while the ductility decreased. The dependences of the critical plastic strain on strain rate and temperature exhibited "inverse" behavior that was associated with concentrated solid solution in the DSA regime. © 2010 IOP Publishing Ltd.


Nikulin I.,Belgorod State University | Kaibyshev R.,Belgorod State University | Skorobogatykh V.,Central Research Institute for Machine Building Technology
Journal of Physics: Conference Series | Year: 2010

Tensile properties of the 18Cr-9Ni-W-Nb-V-N austenitic stainless steel were studied at strain rates ranging from 6.7×10 -6 to 1.3×10 -2 s -1 in the temperature interval 20-740°C. It was found that this steel exhibits jerky flow at temperatures ranging from 530 to 680°C and an initial strain rate of 1.3×10 -3 s -1. This phenomenon was interpreted in terms of Portevin-Le Chatelier (PLC) effect occurring due to dynamic strain aging (DSA). PLC yields significant increase in high temperature strength of this steel due to extending of plateau on temperature dependence of yield strength (YS) and ultimate tensile strength (UTS) to higher temperatures. As a result, YS and UTS remain virtually unchanged with increasing temperature from 350 to 740°C. Role of additives of tungsten and vanadium in DSA and high temperatures strength of the austenitic stainless steel is discussed. © 2010 IOP Publishing Ltd.


Kipelova A.,Belgorod State University | Kaibyshev R.,Belgorod State University | Belyakov A.,Belgorod State University | Schenkova I.,Central Research Institute for Machine Building Technology | Skorobogatykh V.,Central Research Institute for Machine Building Technology
Advanced Materials Research | Year: 2010

The microstructural changes in a 3%Co modified P911 heat resistant steel were examined under static annealing and creep at elevated temperatures. The quenched steel was tempered at temperatures ranging from 673 to 1073 K for 3 hours. The temperature dependence of hardness for the tempered samples exhibits the maximum at 723 - 823 K which is associated with the precipitations of fine carbides with an average size of about 20 nm. The transverse lath size of martensitic structure is ∼200 nm after air quenching and remains unchanged under tempering at temperatures below 800 K. An increase in tempering temperature to 1073 K resulted in hardness drop. Coagulation of carbides and growth of martensitic laths takes place at these temperatures. The creep tests were carried out at 873 and 923 K up to rupture, which occurred after about 4.5 × 103 hours. The structural changes in crept specimens were characterized by the development of coarse laths/subgrains. The mean transverse size of which was ∼0.67 and ∼1.3 μ m after the creep tests at 873 and 923 K, respectively. On the other hand, an average size of second phase particles of ∼165 nm was observed in the samples tested at both temperatures. © (2010) Trans Tech Publications.


Fedorova I.,Belgorod State University | Belyakov A.,Belgorod State University | Kozlov P.,Central Research Institute for Machine Building Technology | Skorobogatykh V.,Central Research Institute for Machine Building Technology | And 2 more authors.
Materials Science and Engineering A | Year: 2014

The precipitation of the Laves-phase in a low-carbon 9% Cr heat resistant steel was studied under conditions of aging and creep at 923K. The Laves-phase of Fe2(W,Mo)-type with a ratio of Mo:W of 1:5 was observed on various boundaries in a tempered martensite structure after a long period of aging/creep. The Laves-phase precipitations provided effective stabilization of the tempered martensite lath structure and therefore promoted creep resistance, although their effect on the dislocation substructure was negligibly small. The mean size of the Laves-phase particles (D) gradually increased with aging/creep time (τ) and could be expressed as D4-D04=Kτ, were K=5×10-34m4/s for aging and K=13×10-34m4/s for creep. The large Laves-phase particles, which coarsened during the creep tests, served as preferential sites for pore and crack nucleation leading to fracture. © 2014 Elsevier B.V.


Kaibyshev R.O.,Belgorod State University | Skorobogatykh V.N.,Central Research Institute for Machine Building Technology | Shchenkova I.A.,Central Research Institute for Machine Building Technology
Metal Science and Heat Treatment | Year: 2010

Prospects of commercial use of new-generation martensitic thermomechanical steels created on the basis of Fe-11% Cr steels are considered. The physical causes of degradation of mechanical properties in the process of creep of these steels at > 590°C are studied in detail. It is shown that the degradation is connected with formation of the Z-phase. The mechanisms of formation of the phase are described. © 2010 Springer Science+Business Media, Inc.


Danilov V.N.,Central Research Institute for Machine Building Technology | Voronkov I.V.,Central Research Institute for Machine Building Technology
Russian Journal of Nondestructive Testing | Year: 2010

The main principles of the formation of signals of a linear normal phased-array transducer are considered. Directivity characteristics (DCs) are calculated as functions of the number of emitting elements, the array dimensions, and the distance. It has been established that the DCs of such a transducer are similar to the pulsed DCs of an ordinary transducer of somewhat smaller dimensions. The presence of the near-field zone within which the DCs are formed is shown. © 2010 Pleiades Publishing, Ltd.


Danilov V.N.,Central Research Institute for Machine Building Technology
Russian Journal of Nondestructive Testing | Year: 2010

The acoustic path of an angle transducer is calculated in the Kirchhoff approximation for a reflector of the flat-bottom-hole type. The formula obtained can be used for constructing DGS diagrams. In the limiting case of the far-field zone, an asymptotic formula is obtained for the acoustic path confirming the validity of using analogous relationships, which were heuristically obtained earlier. Numerical calculations of the DGS diagram of an angle transducer are performed, the results of which are compared to those obtained via the recalculation of the diagram for a normal transducer. © Pleiades Publishing, Ltd., 2010.


Danilov V.N.,Central Research Institute for Machine Building Technology
Russian Journal of Nondestructive Testing | Year: 2010

On the basis of an earlier developed model on scattering of transverse waves at a crack in the form of a strip, exact and approximate (estimated) scattering indicatrices for transverse and longitudinal elastic waves are studied, taking into account the influence of their transformation at the flat free surface of a reflector into other wave types on the change in the Echo-signal amplitude. The limits of applicability of the estimated indicatrices for mirror and back reflections are numerically studied. The exact results for longitudinal waves are compared to those obtained by the Kirchhoff method. © 2010 Pleiades Publishing, Ltd.


Danilov V.N.,Central Research Institute for Machine Building Technology
Russian Journal of Nondestructive Testing | Year: 2010

Some features in the formation of the signals of a normal linear transducer with a phased array are studied. The characteristics of the signals from a normal linear transducer with a phased array and a radiating element in the form of an elongated rectangular piezoelectric plate are compared. It is shown how much the amplitude of a signal that is focused and radiated along the acoustic axis exceeds that of a signal from a conventional transducer with an extensive radiating element. An analytical equation describing the dependence of the signal amplitude on the distance along the focusing direction at a specified angle to the acoustic axis is deduced. © Allerton Press, Inc., 2010.


Ushakov V.M.,Central Research Institute for Machine Building Technology | Davydov D.M.,Central Research Institute for Machine Building Technology
Russian Journal of Nondestructive Testing | Year: 2013

A review is presented of modern ISO and EN standards for the ultrasonic testing of welded joints. Special attention is paid to practical implementation of standard requirements that concern setting flaw-detector sensitivity and quality assessment based on the results of ultrasonic testing. © 2013 Pleiades Publishing, Ltd.

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