Number of found documents: 906
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Effect of grit blasting surface treatment on high temperature low cycle fatigue life of Inconel 713LC
Šulák, Ivo; Obrtlík, Karel; Čelko, L.; Gejdoš, P.
2015 - English
This paper presents the results of high temperature low cycle fatigue tests carried out on Inconel 713LC. This polycrystalline nickel based superalloys is mainly used for high temperature applications such as disks, blades and vanes of gas turbine engines. These machine components are manufactured by investment casting and undergo a series of postcast processes to remove remnants of shells, oxides and other contaminants. Grit blasting is one of the most widely used and cheapest technology ensuring adequate cleaning of the surface and at the same time is used to treat the substrate surface prior to application of metalic bond coat and various protective coatings (like diffusion, overlay or thermall barier coatings). Low cycle fatigue tests were conducted on as-received and grit blasted material in fully reversed pull-push cycle in strain control mode with constant total strain amplitude and strain rate at 900 °C in air. Experimental data on fatigue life were evaluated and parameters of Baquin and Coffin-Manson curves were obtained for both tested materials. Specimen surface and cross sections of both treated and untreated materials were analysed prior to fatigue tests and also after testing by means of optical microscopy (OM), as well as scaning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) and Vickers microhardness was measured. Fatigue degradation mechanisms was documented in both materials and negligible effect of grit blasting on low cycle parameters was discussed. Keywords: Grit blasting; Surface relief; Surface microhardnes; High temperature fatigue life; Inocel 713LC Available at various institutes of the ASCR
Effect of grit blasting surface treatment on high temperature low cycle fatigue life of Inconel 713LC

This paper presents the results of high temperature low cycle fatigue tests carried out on Inconel 713LC. This polycrystalline nickel based superalloys is mainly used for high temperature ...

Šulák, Ivo; Obrtlík, Karel; Čelko, L.; Gejdoš, P.
Ústav fyziky materiálů, 2015

MAGNETIC AND TRANSPORT PROPERTIES OF 41CRMO4 STEEL
Bulín, T.; Hapla, Miroslav; Roupcová, Pavla; Ondrůšek, Č.; Schneeweiss, Oldřich
2015 - English
We have measured magnetic parameters and electrical resistivity of 41CrMo4 steel. It consist ferrite, Cr7C3 and Cr23C6 type of carbides. The\nmeasurements of temperature dependences of magnetic moments and electrical resistivity confirm phase stability of ferrite. The room temperature resistivity, saturation magnetization at room temperature, as well as AC measurements was measured. The power losses are strongly dependent on frequency and excitations. Keywords: 41CrMo4 steel; magnetic properties; electrical resistivity Available at various institutes of the ASCR
MAGNETIC AND TRANSPORT PROPERTIES OF 41CRMO4 STEEL

We have measured magnetic parameters and electrical resistivity of 41CrMo4 steel. It consist ferrite, Cr7C3 and Cr23C6 type of carbides. The\nmeasurements of temperature dependences of magnetic ...

Bulín, T.; Hapla, Miroslav; Roupcová, Pavla; Ondrůšek, Č.; Schneeweiss, Oldřich
Ústav fyziky materiálů, 2015

Analysis of nanoparticles released from the car brakes
Švábenská, Eva; Roupcová, Pavla; Schneeweiss, Oldřich
2015 - English
Our research is focused on the phase, structure and chemical analysis of the powder particles released by braking of cars from their brake components – discs and pads. The basic information on structure and phase composition was obtained by X-Ray Powder Diffraction, Mössbauer Spectroscopy and scanning electron microscopy with EDX. The results of the particle analysis are compared with materials used for manufacturing brake components and with the powder prepared by ball milling of the mixture of the pad composite and disk steel. Most of recognized nanoparticles are based on carbon, silica/silicates and iron oxides. Their effects on street environment are mentioned. Keywords: nanoparticles; wear debris; automotive brake Available at various institutes of the ASCR
Analysis of nanoparticles released from the car brakes

Our research is focused on the phase, structure and chemical analysis of the powder particles released by braking of cars from their brake components – discs and pads. The basic information on ...

Švábenská, Eva; Roupcová, Pavla; Schneeweiss, Oldřich
Ústav fyziky materiálů, 2015

Thermo-mechanical and isothermal fatigue behavior of austenitic stainless steel AISI 316L
Škorík, Viktor; Šulák, Ivo; Obrtlík, Karel; Polák, Jaroslav
2015 - English
Many structural components of nuclear power plant systems are made of austenitic stainless steels. These structures undergo degradation by thermo-mechanical fatigue (TMF) caused by simultaneous cyclic straining and temperature cycling, particularly during start-up, shut-down and transient operations. The present work reports the cyclic deformation behavior and fatigue damage of austenitic stainless steel AISI 316L during TMF and isothermal fatigue (IF) testing in air. Total strain controlled in-phase TMF loading in the temperature range 200 - 600 °C and isothermal fatigue (IF) at 600 °C were performed. Hardening/softening curves, cyclic stress-strain response and fatigue life diagrams were obtained both for TMF and IF tests. Fatigue damage was documented using surface relief and fracture surface observations. Mean stress evolution and fatigue degradation data are employed to discuss the fatigue behavior of 316L steel both in TMF and IF regimes. Keywords: Thermo-mechanical fatigue (TMF); In-phase cycling (IP); Isothermal fatigue (IF); AISI 316L; Fatigue life Available at various institutes of the ASCR
Thermo-mechanical and isothermal fatigue behavior of austenitic stainless steel AISI 316L

Many structural components of nuclear power plant systems are made of austenitic stainless steels. These structures undergo degradation by thermo-mechanical fatigue (TMF) caused by simultaneous cyclic ...

Škorík, Viktor; Šulák, Ivo; Obrtlík, Karel; Polák, Jaroslav
Ústav fyziky materiálů, 2015

Analysis of slag material in the production of zinc oxide
Luptáková, Natália; Pešlová, F.
2014 - English
The given paper is closely connected with determination of character and morphology of slag generated in the production of ZnO. Hazardous situations relating to occurrence of these elements are hidden in their ability to create ternary eutectic formations and in terms of mechanical properties, they have ability to create quite fragile structure. The presence of oxygen as well as high temperature causes adhesion of ternary eutectic. Zinc slag has the influence on rapid degradation of the linings and moreover it also decreases the production quality of ZnO. Analysis results are significant information for minimizing of waste material and easier removing of stuck slag. Keywords: zinc slag; production of zinc oxide; analysis of slag; phases Available at various institutes of the ASCR
Analysis of slag material in the production of zinc oxide

The given paper is closely connected with determination of character and morphology of slag generated in the production of ZnO. Hazardous situations relating to occurrence of these elements are hidden ...

Luptáková, Natália; Pešlová, F.
Ústav fyziky materiálů, 2014

Investigation of Mechanical Properties of Fe3Al-Based Alloys with Vanadium and Carbon Additions by Small Punch Test
Dobeš, Ferdinand; Dymáček, Petr; Kratochvíl, P.; Král, R.; Çelikyürek, I.; Torun, O.
2014 - English
Additions of carbon and carbide-forming elements can positively influence high temperature mechanical properties of alloys based on Fe3Al intermetallic compound. In the present study, the effect of vanadium and carbon additions on mechanical properties of Fe3Al-type alloy is investigated by a combination of small punch tests and conventional tensile and compressive tests. The constant-deflection mode of the small punch test is used to estimate the properties and their temperature dependence. The yield force and the maximum force are evaluated from the force vs. deflection dependence and compared with the corresponding quantities resulting from conventional tests. The comparison is discussed in terms of equations suggested previously by Mao and Takahashi. Modifications suggested recently by Garcia et al. are taken into account as well. Fractographic observations of ruptured specimens are performed with scanning electron microscope. Temperature dependence of small punch test quantities is related to the microscopic image of the fracture. Equivalent fracture strain is evaluated from both small punch test data and microscopic observation of fractured specimens. The relation between equivalent fracture strain and small punch fracture energy is examined. Fracture toughness is calculated from the equivalent fracture strain. Temperature dependence of calculated fracture toughness supports the conclusion that the ductility of investigated alloys is not deteriorated by the presence of carbides. Keywords: small punch; yield stress; ultimate tensile strength Available at various institutes of the ASCR
Investigation of Mechanical Properties of Fe3Al-Based Alloys with Vanadium and Carbon Additions by Small Punch Test

Additions of carbon and carbide-forming elements can positively influence high temperature mechanical properties of alloys based on Fe3Al intermetallic compound. In the present study, the effect of ...

Dobeš, Ferdinand; Dymáček, Petr; Kratochvíl, P.; Král, R.; Çelikyürek, I.; Torun, O.
Ústav fyziky materiálů, 2014

Mechanical alloying of Fe-X (X=Al, Mo, Ni) powders studied by analytical electron microscopy
Buršík, Jiří; Jirásková, Yvonna
2014 - English
Mechanical alloying via ball milling represents a relatively simple way of preparing materials with a micro-to nanograin crystalline and/or amorphous metastable structure. Keywords: Fe-X (X=Al, Mo, Ni); SEM and TEM; EDX Available at various institutes of the ASCR
Mechanical alloying of Fe-X (X=Al, Mo, Ni) powders studied by analytical electron microscopy

Mechanical alloying via ball milling represents a relatively simple way of preparing materials with a micro-to nanograin crystalline and/or amorphous metastable structure.

Buršík, Jiří; Jirásková, Yvonna
Ústav fyziky materiálů, 2014

On an estimation of the exponent of the stress singularity: three dimensional problems and effect of residual stresses on a crack arrested on the interface
Máša, Bohuslav; Náhlík, Luboš; Hutař, Pavel
2014 - English
The main aim of this paper is an investigation of the crack behavior in the ceramics laminates. Especially, the problem of the estimation of the stress singularity exponent in such a material using different approaches is closely described. Since analytical approach is a suitable tool for two dimensional problems, introducing residual stresses, which can be result of used procedures during composite production, may influence value of the stress singularity exponent. Unfortunately, there is formally no analytical tool available to introduce residual stresses. Moreover, when the three dimensional geometry is investigated, effects of complicated stress distribution in front of the crack tip are of crucial importance for crack behavior. Hence using numerically obtained stress distribution appears to be the only way, how to capture the effect of residual stresses and three dimensional geometry of the crack front. The stress singularity exponent can be directly determined from stress components in front of the crack tip and/or from displacements at faces of the crack. Both can provide good results and give us a solution, which cannot be obtained analytically. In following text the procedure will be described in more detail and shown results obtained on ceramic laminate. Keywords: Stress singularity exponent; Residual stress; Singular stress concentrator; Material interface; Ceramic composites Available at various institutes of the ASCR
On an estimation of the exponent of the stress singularity: three dimensional problems and effect of residual stresses on a crack arrested on the interface

The main aim of this paper is an investigation of the crack behavior in the ceramics laminates. Especially, the problem of the estimation of the stress singularity exponent in such a material using ...

Máša, Bohuslav; Náhlík, Luboš; Hutař, Pavel
Ústav fyziky materiálů, 2014

Effect of residual elements on quality of pure zinc
Luptáková, Natália; Pešlová, F.; Stodola, J.
2014 - English
The paper deals with the nature and morphology of the input material for the production of metallic zinc which is used in the production of ZnO through indirect pyrometallurgical processes. The input material is the key parameter in the production of high-quality zinc oxide. For the prediction of complex production process when problematic situation may occur, the systematic analysis of the input zinc raw materials is needed. Undesirable phases in the feedstock can be identified through profound recognition of the source material and the nature of its microstructure. Chemical composition of zinc metal and zinc additives helps to detect the phases occurring in the matrix. Undesirable phases in the feedstock can form (with zinc and other elements) hard and brittle compounds. If these compounds diffuse into the lining during thermal processes, they become the cause of stress in metallurgical ceramics. The emergence of these chemical reactions may subsequently affect the entire metallurgical zinc smelting process. From the microstructure viewpoint, the heterogeneity of grain size, various morphology of intermediate phases, their layout, arrangement, etc. can be expected. The results obtained by analysis are used to minimize waste - zinc slag and to eliminate the conditions which enable the formation of the undesired product, thereby increasing the productivity of the zinc oxide production. Keywords: zinc; metallurgical process; phases; residual elements Available at various institutes of the ASCR
Effect of residual elements on quality of pure zinc

The paper deals with the nature and morphology of the input material for the production of metallic zinc which is used in the production of ZnO through indirect pyrometallurgical processes. The input ...

Luptáková, Natália; Pešlová, F.; Stodola, J.
Ústav fyziky materiálů, 2014

Crack under biaxial loading: Two-parameter description
Seitl, Stanislav; Bermejo, C. S.
2014 - English
A two-parameter approach for description of stress field for isotropic materials under biaxial loading was proposed in this contribution. From the results, it was found that analysis using the two-parameter fracture mechanics is an effective way to evaluate stress fields under biaxial stress. Keywords: Biaxial loading; T-stress; stress intensity factor; crack Available at various institutes of the ASCR
Crack under biaxial loading: Two-parameter description

A two-parameter approach for description of stress field for isotropic materials under biaxial loading was proposed in this contribution. From the results, it was found that analysis using the ...

Seitl, Stanislav; Bermejo, C. S.
Ústav fyziky materiálů, 2014

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