Wyniki wyszukiwania - BazTech

1

Fatigue crack growth resistance of welded joints simulating the weld-repaired railway wheels metal

Ostash O. P., Kulyk V. V., Poznyakov V. D., Haivorons’kyi O. A., Markashova L. I., Vira V. V., Duriagina Z. A., Tepla T. L.

Archives of Materials Science and Engineering

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2017

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Vol. 86, nr 2

49--55

EN

Purpose: The aim of the paper is to study the structure and fatigue crack growth resistance characteristics of weld metal (WM), and heat affected zone (HAZ) under cyclic loadings for the development of railway wheels weld-repairing technology. Design/methodology/approach: WM and HAZ of the welded joint were investigated. The welded joint of 65G steel (0.65 mass.% C; 0.19 Si; 0,91 Mn), which is a model material for high-strength railway wheels, was received by welding Sv-08HM wire per linear welding energy of 10 kJ/cm. Regimes of welding were selected so that the cooling rate of the metal in the temperature range 500-600°C was 5°C/s. As a result, the bainite structure in WM and bainite-martensite one in HAZ are formed. To eliminate the residual stresses generated after the weld cooling, heat treatment was proposed: holding at 100°C for 2 hour after cooling under temperature below then that at the beginning of martensite transformation. Fracture resistance under cyclic loading was estimated by fatigue crack growth rates diagrams (da/dN vs. ΔK) according to standard method for compact tension samples testing. The microstructure and fracture surface were investigated using an optical, and electronic scanning and transmission microscope. Findings: Microstructure parameters and fatigue crack growth resistance characteristics of WM and HAZ after the proposed heat treatment, and also residual stresses of the second kind and local strains in the bulk of bainite and martensite are obtained. Research limitations/implications: Investigations were conducted on samples that simulate the structure and properties of real renovated railway wheels made of steel with high content (0.65%) of carbon. Practical implications: Service durability and safety of weld-repaired railway wheels under high service loadings is increased. Originality/value: HAZ is the most dangerous zone in terms of fatigue cracks initiation and propagation in elements repaired by surfacing method. The positive result on the proposed heat treatment influence is received since the fatigue crack growth resistance characteristics of HAZ metal with bainite-martensite structure raise to the level of weld metal.

2

Evaluation of effect of surface quality of machined rail way wheels on fatigue strength

Fajkoš R., Zima R.

Czasopismo Techniczne. Mechanika

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2014

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R. 111, z. 1-M

19--32

EN

Railway transport capacities all over the world have been growing, a phenomenon which is accompanied by the requirement to increase axle loads of freight rolling stock. Apart from new wheel designs for higher axle loads, the requirements of their safety and reliability have also been growing, since these wheels are often used in extreme climactic conditions. Cruising speeds of passenger trains been increasing, which likewise brings more stringent requirements concerning the quality and safety of the supplied railway wheels. This paper describes methods of evaluating fatigue strength of railway wheel webs and methods of evaluating the quality of machined railway wheel webs. Results of fatigue tests performed on wheels machined in a standard way are compared with wheels which have been treated by shot peening, a treatment frequently used to increase the fatigue strength of wheel webs of the railway wheelset.

PL

Możliwości transportu kolejowego rosną na całym świecie, co powoduje zwiększenie nacisku na osi towarowego taboru kolejowego. Projekty nowych kół oprócz uwzględnienia wyższych nacisków na oś, muszą również uwzględnić rosnące warunki dotyczące bezpieczeństwa i niezawodności, ponieważ takie koła często stosowane są w ekstremalnych warunkach klimatycznych. Także wzrost prędkości przelotowej pociągów niesie za sobą bardziej rygorystyczne wymagania co do bezpieczeństwa jakości dostarczanych kół kolejowych. W pracy opisane zostały metody oceny wytrzymałości zmęczeniowej kołnierzy kół kolejowych oraz metody oceny jakości obrabianych kołnierzy kół. Wyniki przeprowadzonych badań zmęczeniowych kół obrabianych w standardowy sposób porównano z kołami, które traktowane były przez śrutowanie – obróbkę często stosowaną w celu zwiększenia wytrzymałości zmęczeniowej kołnierzy kół kolejowych zestawów kołowych.

3

Non-uniformity of deformation as an important factor of ovality formation in the billets for railway wheels at free upsetting with figured dies

Dyja H., Danchenko V., Shramko A., Chukhlib A., Ashkelianets A.

Hutnik, Wiadomości Hutnicze

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2011

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Vol. 78, nr 5

365--369

EN

The paper presents research results of non-uniformity of deformation as important factor of ovality formation in the billets for railway wheels at free upsetting with figured dies. For the numerical modeling of the upsetting process the FORGE computer software, which based on finite element method was used. The physical modelling of the process of free upsetting was carried out on the lead samples, on the universal testing machine GMS-50.

PL

W pracy przedstawiono wyniki badań nierównomierności odkształcenia jako ważnego czynnika kształtowania owalności w kęsach na koła kolejowe, podczas kucia swobodnego w kowadłach kształtowych. Do numerycznego modelowania procesu kucia zastosowano komputerowy program FORGE, bazujący na metodzie elementów skończonych. Modelowanie fizyczne kucia swobodnego zostało przeprowadzone na próbkach z ołowiu, na uniwersalnej maszynie testującej GMS-50.

4

Influence of nonmetallic inclusions on microbreaks formation in wheel steel and railway wheels

Gubenko S., Proidak Y., Kozlovsk'yy A., Shramko O., Is'kov M.

Transport Problems

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2008

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T. 3, z. 3

77-81

EN

It is well known that formation of defects of many types during railway wheels service somehow or other is connected to nonmetallic inclusions in wheel steel. Microbreakes connected with nonmetallic inclusions have different origin. The first one is "deformational", the second is "thermal" and the third is "hydrogenous". The objective of this work is the study of nature of microbreaking in wheel steel relative to nonmetallics. Mechanisms of microbreaking of all types near different nonmetallics had been investigated and their influence on safety threshold of railway wheels had been analyzed herein.

5

Dynamics of wheel-tyre subjected to moving oscillating force

Bogacz R., Kocjan M., Kurnik W.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2002

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Vol. 6, No 3

343-350

EN

The subject of the paper is analysis of wheel of a moving railway vehicle which is subjected to a moving oscillating force. Rail ring is treated as a beam of small curvature connected to wheel axle with a Winkler foundation. Bernoulli-Euler and Timoshenko beam model is used. Results are gained using Fourier transformation. Space and space-time graphs, showing wave propagation in subcritical and supercritical zones of excitation, concerning resonance of transverse vibrations, are included.