Wyniki wyszukiwania - BazTech

1

The effect of the mixing method of the addition of Gilsonite natural bitumen on asphalt mixture properties

Bilski Marcin, Mielczarek Marta, Górnaś Przemysław, Słowik Mieczysław, Wojciechowska Patrycja

Roads and Bridges - Drogi i Mosty

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2022

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Vol. 21, no. 3

239--251

EN

The paper presents the results of laboratory tests performed on asphalt concrete mixtures modified with addition of Gilsonite natural bitumen (4% content in the weight of binder). Gilsonite was introduced into asphalt concrete using two methods: wet mixing and dry mixing. The laboratory tests encompassed determination of stiffness modulus in indirect tensile test, stiffness modulus in static creep test and resistance to water and frost. Based on statistical analysis of the obtained results, significance of differences was evaluated for the parameters of asphalt concrete modified with addition of Gilsonite (both wet-mixed and dry-mixed) and an unmodified reference mixture. It was determined that the method ("wet" or "dry") of mixing Gilsonite into the analyzed asphalt concrete mixture does not have a significant effect on the values of stiffness modulus in IT-CY test, static creep test stiffness modulus or the indirect tensile strength ratio ITSR.

PL

W pracy przedstawiono wyniki badań laboratoryjnych mieszanek mineralno-asfaltowych (MMA) typu beton asfaltowy, które zawierały w swoim składzie dodatek asfaltu naturalnego Gilsonite w ilości 4% w stosunku wagowym do masy asfaltu, dozowany dwiema metodami: „na mokro" lub „na sucho”. Zakres przeprowadzonych badań laboratoryjnych obejmował oznaczenie modułów sztywności w badaniach pośredniego rozciągania, modułów sztywności metodą pełzania pod obciążeniem statycznym oraz odporności na działanie wody i mrozu. Na podstawie analizy statystycznej otrzymanych wyników badań laboratoryjnych dokonano oceny istotności różnic w uzyskanych właściwościach MMA zawierających dodatek Gilsonite dozowany różnymi metodami, w porównaniu do wartości uzyskanych na mieszance referencyjnej. Ustalono, że metoda dozowania („na mokro" lub „na sucho") dodatku asfaltu naturalnego Gilsonite do analizowanej mieszanki mineralno-asfaltowej typu beton asfaltowy nie ma istotnego wpływu na wartości modułów sztywności oznaczonych metodą IT-CY, metodą pełzania, a także na wartości wskaźnika wytrzymałości na rozciąganie pośrednie ITSR.

2

The study of the evolution of the microstructure and creep properties of Super 304H austenitic stainless steel after aging for up to 50,000 h

Zieliński A., Wersta R., Sroka Marek

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 2

art. no. e89, 1--24

EN

The paper discusses several aspects of degradation of Super 304H steel subjected to long-term aging up to 50,000 h at 650 and 750°C. The study includes microstructure examination by scanning and transmission electron microscopy along with X-ray microanalysis of a wide range of precipitates. The Super 304H steel has a structure characteristic for austenitic steels with annealing twins and single primary NBX precipitates of various sizes. Long-term aging leads to precipitation of several phases such as M23C6, MX carbides, σ phases, Z phase and ε-Cu phase. The precipitation processes lead to changes in the creep strength of the tested steel, the value of which strongly depends on the aging temperature used, which is measurably shown by the creep tests carried out with the elongation measured during the test.

3

Cyclic loading–unloading creep behavior of composite layered specimens

Hu Bo, Yang Sheng‑Qi, Xu Peng, Cheng Jian‑Long

Acta Geophysica

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2019

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Vol. 67, no. 2

449--464

EN

Soft and hard interbedded rocks show obvious time-dependent deformation after deep tunnel excavations, and it is therefore necessary to research the mechanical behavior of the layered rock. However, it is hard to obtain ideal transversely isotropic rocks in fields, so rock-like specimens were poured by using artificial materials. Cyclic loading–unloading creep experiments were performed on the artificial layered cemented specimens with various layer angles (0°, 30°, 60° and 90°) at a 20 MPa confinement. Time-independent deformations and time-dependent deformations of the rock-like specimens were distinguished to investigate the visco-elasto-plastic deformation characteristics. Instantaneous elastic strain and instantaneous plastic strain had linear correlations with stress ratio, whereas creep strain, including visco-elastic strain and visco-plastic strain, increased nonlinearly with an increasing stress ratio. The specimens with a small layer angle had more noticeable time-independent and time-dependent deformations and larger steady-state creep rates than those of the specimens with a large layer angle. Attenuation creep and secondary creep could be observed at relative low stress levels, whereas accelerating creep until failure occurred at the creep failure stress level. The time for creep failure can be predicated according to the axial steady-state creep rate or volumetric creep curve. Damage in the rock-like specimens showed linear correlation with the stress ratio. Dip angle has a significant effect on the creep failure mode under cyclic loading–unloading conditions.

4

Ocena stopnia wyeksploatowania materiału wirników turbin parowych z niskostopowej stali Cr-Mo-V po eksploatacji w czasie znacznie przekraczającym czas obliczeniowy

Dziuba-Kałuża M., Dobrzański J., Purzyńska H., Kania-Pifczyk Z., Rozmus R.

Prace Instytutu Metalurgii Żelaza

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2018

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T. 70, nr 1

4--11

PL

Celem pracy była ocena stanu rozwoju procesów wydzieleniowych, wyznaczenie odpowiadającej mu pręd-kości pełzania i wyznaczenie odpowiadającego im stopnia wyczerpania badanych stali 23H2MF, 26H2MF oraz 21HMF po długotrwałej pracy w warunkach pełzania. Przeprowadzono identyfikację występujących wydzieleń w oparciu o ich obraz dyfrakcyjny. Wykonana została próba pełzania z pomiarem wydłużenia w czasie jej trwania dla wyznaczenia prędkości pełzania na materiale wirnika po eksploatacji znacznie poza ob-liczeniowym czasem pracy. Wykonano badania mikrostruktury w skaningowym mikroskopie elektronowym, wyznaczono skład fazowy węglików metodą rentgenowskiej analizy fazowej.

XX

The aim of the work was to assess the state of development of precipitation processes, determine the corresponding creep speed, and determine the corresponding degree of exhaustion of 23H2MF, 26H2MF and 21HMF steels after long-term work under creep conditions. The identification of precipitates based on their diffraction pattern was carried out. A creep test was performed with the measurement of elongation during its duration to determine the creep speed on the rotor material after use in time significantly exceeding its computational working time. Microstructure investigations were carried out using a scanning electron microscope, and phase composition of carbides was determined with the use of X-ray phase analysis.

5

Evaluation of Creep Strength of Heterogeneous Welded Joint in HR6W Alloy and Sanicro 25 Steel

Zieliński A., Dobrzański L., Purzyńska H., Sikora R., Dziuba-Kałuża M., Kania Z.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 4

2057--2064

EN

This article presents the results of investigations on HR6W alloy and Sanicro 25 steel and the dissimilar welded joint made of them. The characteristic images of microstructure of the investigated materials in the as-received condition and following the creep test, observed with a scanning electron microscope (SEM), are shown. The X-ray analysis of phase composition of the existing precipitates was carried out. The method for evaluation of creep strength based on abridged creep tests carried out at a temperature higher than the design one is presented. The obtained results do not deviate from the values of creep strength determined in long-term creep tests. The maximum difference in creep strength of the investigated materials is ±20%, which is in compliance with the acceptable scatter band. The methodology presented can be used for verification of creep strength (life time) of the material of finished components to be operated under creep conditions.

6

Metallographic study of porosity in IN713C superalloy in as-cast and after creep test

Szczotok A.

Czasopismo Techniczne. Mechanika

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2016

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Y. 113, iss. 4-M

21--26

EN

The paper summarizes the results of observation and quantitative analysis of porosity in IN713C superalloy in as-cast and after the creep test. The sources of porosity in castings are shortly described and the methodology of pores measurement is circumscribed. The results of pores in as-cast and after the creep test were shown and, finally, the interpretation of the result was presented.

PL

W artykule przedstawiono wyniki obserwacji i badań ilościowych porowatości występującej w nadstopie IN713C w stanie lanym i po próbie pełzania. Scharakteryzowano pokrótce źródła powstawania porowatości w odlewach. Metodyka pomiaru porów opisano i przedstawiono uzyskane wyniki pomiarów wraz z ich interpretacją.

7

Characteristics of changes in properties and structure of X10CrMoVNb9-1 steel due to long-term impact of temperature and stress

Zieliński A., Dobrzański J.

Archives of Materials Science and Engineering

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2013

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Vol. 60, nr 2

72--81

EN

Purpose: this article presents the results of mechanical and structure testing of X10CrMoVNb9-1 (P91) steel in initial state and after annealing, creep tests and long-term service under creep conditions Design/methodology/approach: The material for investigations was X10CrMoVNb9-1 (P91) steel in the form of two test pieces of tubes with dimensions of Ø355.6x50 mm and Ø325x38 mm in initial state and after 90,000 h service under creep conditions, respectively. The mechanical and structure testing was carried out on material in initial state and after long-term service under creep conditions. The microstructure was observed using scanning electron microscope. Findings: The mechanical, creep and structure testing of steel in initial state has confirmed that the tested steel meets the requirements of PN-EN 10216-2. Long-term annealing as well as hardness and impact strength testing have allowed the influence of long-term impact of temperature and time on properties and structure of X10CrMoVNb9-1 (P91) steel to be evaluated. Practical implications: The presented method can be used for evaluation and qualification of structural changes in power station boiler components operating under creep conditions. Originality/value: The presented results of changes in mechanical properties, structure and precipitation processes are applied to evaluation of the condition of elements for further industrial service.

8

Analiza zależności wyników pełzania metodą małych próbek i konwencjonalnej próby pełzania

Mierzwiński D.

Archiwum Odlewnictwa

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2006

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R. 6, nr 21/1

361-368

PL

Bezpieczna eksploatacja urządzeń energetycznych w szczególności walczaków oraz wirników turbin parowych związana jest z określeniem bezawaryjnego czasu pracy w oparciu o badania diagnostyczne. Stosowane dotychczas badania trwałości urządzeń energetycznych są procesami kosztownymi i czasochłonnymi. Alternatywą badania pełzania stali może być metoda małych próbek nazywana Small Punch Test (SPT).

EN

The safe exploitation of energetic devices insist on precise describing of failurefree working time. Vary important to describe of failure-free working time is diagnostic checking. Conventional tests ordinary used to determination of operational safety are expensive and time-consuming. As an alternative to conventional creep test the innovatory method called Small Punch Test could be introduced.

9

Microstructure and texture of PM2000 tubes - correlation with multiaxial creep and failure behaviour.

Wasilkowska A., Ratuszek W., Penkalla H.J., Kędzierski Z., Czyrska-Filemonowicz A.

Inżynieria Materiałowa

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1998

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R. XIX, nr 4

1187-1190

EN

A relationship between the microstructure and multiaxial creep properties of PM2000 tubes is discussed. The microstructure was investigated by X-ray diffraction, optical metallography, scanning- and transmission electron microscopy (TEM). Creep properties were established at 1000 degrees centigrade under multiaxial loading. The results show a low creep ductility and intergranular failure of tubes at high temperatures, related to the microstructural and mechanical anisotropy. The development of a special pancake grain structure is seen as a factor for increasing the life time of tubes subjected to multiaxial creep.