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1

Quasi-Static and Dynamic Testing of Carbon Fiber Reinforced Magnesium Composites

Ranachowski Z., Ranachowski P., Brodecki A., Kopeć M., Kudela S. jr.

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 2

893--899

EN

Two types of composites, consisting of pure magnesium matrix reinforced with two commercially used carbon fibers, were systematically studied in this paper. The composites fabricated by the pressure infiltration method, were subjected to quasistatic and dynamic compression tests. Morphology of fiber strands was observed using scanning electron microscope (SEM). The application of carbon fibre reinforcement led to the stiffening of tested materials, resulting in the limitation of the possible compression to approx. 2.5%. The performed tests revealed the remarkable difference in compression strength of investigated compositions. The cause of that effect was that GRANOC fiber reinforced composite exhibited insufficient bond quality between the brittle fibers and the ductile matrix. T300 reinforced composite presented good connection between reinforcement and matrix resulting in increased mechanical properties. Investigated composites demonstrated higher mechanical strength during deformation at high strain rates. Microscopic observations also proved that the latter fibers with regular shape and dense packaging within the filaments are proper reinforcement when designing the lightweight composite material.

2

Comparative Studies on Degradation of Varistors Subjected to Operation in Surge Arresters and Surge Arrester Counters

Papliński P., Wańkowicz J., Śmietanka H., Ranachowski P., Ranachowski Z., Kudela S. jr., Aleksiejuk M.

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 1

367--374

EN

The paper presents results of investigation of microstructure and micro-hardness for material of ZnO varistors applied to 110 kV surge arrester and surge arrester counter. The research combined two pairs of varistors, each consisted of one varistor subjected before to operation, while the other one was brand new unit and constituted a reference. All varistors were made of the same material by the reputable manufacture. The tests revealed a different degree of the material degradation for varistors subjected before to operation. This also refers to different degradation mechanism observed for the material of these varistors, if typical effects of degradation of aged ZnO varistors were considered as a reference. Physical state of spinel in the microstructure had a significant impact on the material degradation, however a considerable loosening of the microstructure associated with bismuth oxide was observed too. It was surprising, since the precipitates of the bismuth oxide phase most often showed very good binding to the ZnO matrix and high resistance to associated electrical, thermal and mechanical effects. The degradation effects in the ZnO matrix proved to be limited only.

3

Investigation of Microstructure of ZnO Varistors Taken From Surge Arrester Counters

Papliński P., Wańkowicz J., Ranachowski P., Ranachowski Z.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 1

191--196

EN

The paper presents investigations of microstructure of varistors of damaged surge arrester counters. A similar ZnO varistor, not subjected before to operation, was a point of reference in this research. The results of investigations of the ZnO varistors show an untypical phase composition of their material, which was characterized by unsatisfying homogeneity and cohesion. The degradation processes of varistor material in the subsequent stages were recognized and described. A harmful impact of humidity inside the untight surge arrester counter on its operation and its ZnO varistors was proved. Some conclusions being the result of the operation checking of surge arrester counters were presented too.

4

Doświadczenia z eksploatacji wysokonapięciowych liczników zadziałań oraz badania degradacji mikrostruktury pochodzących z nich warystorów ZnO

Papliński P., Wańkowicz J., Ranachowski P., Ranachowski Z.

Przegląd Elektrotechniczny

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2018

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R. 94, nr 10

1--7

PL

W pracy przedstawione zostały doświadczenia z eksploatacji liczników zadziałań, które stanowiły inspirację do badań pochodzących z nich warystorów ZnO. Badana była mikrostruktura elementów pochodzących z uszkodzonych liczników zadziałań. Odniesienie stanowił analogiczny warystor, z licznika który nie był w eksploatacji. Badania wykazały nietypowy skład fazowy tworzywa badanych warystorów oraz niską jednorodność i spoistość ich czerepu. Opisano i udokumentowano procesy degradacji tworzywa o zróżnicowanym nasileniu. Wykazano szkodliwy wpływ wilgoci we wnętrzu rozszczelnionego licznika zadziałań na jego funkcjonowanie, w tym na umieszczone w nim warystory ZnO. Przedstawiono ponadto wnioski dotyczące kontroli eksploatacyjnej liczników zadziałań.

EN

The paper presents experience from exploitation of surge arrester counters. There was documented destructive influence of humidity inside the untight surge arrester counter on its operation and ZnO varistors within. There were presented examinations of microstructure of varistors of damaged surge arrester counters. A point of reference was similar ZnO varistor, not subjected to operation before. Investigations revealed that material of varistors had an untypical phase composition and was characterized by unsatisfying homogeneity and cohesion. There were recognized and described the subsequent stages of the degradation processes of varistors material. Conclusions resulting from the operation checking of surge arrester counters were also presented.

5

Study of Modified Aluminous Porcelain Subjected to Mechanoacoustic Tests

Ranachowski P., Ranachowski Z., Wieczorek K., Jaroszewski M., Kudela S. jr.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 4

1821--1826

EN

The paper presents the microscopic and mechanoacoustic study of degradation processes of the porcelain material C 130 type. This kind of material is used in the production of the most durable and reliable electrotechnical elements. Raw material composition of the studied porcelain was modified. This had an impact on the inner properties, cohesion and – in consequence – on operational properties of the material. Using mechanical-acoustic and microscopic methods of testing of small-size samples that were subjected to compression, it was possible to distinguish successive stages of degradation of the porcelain structure. These stages were generally typical of the porcelain materials. In the authors’ opinion, they are connected to the ageing process happening over many years of work under operating conditions. Optimization of composition and technological properties – important during technological processes – resulted in a slight decrease in inner cohesion of the porcelain. When compared to the reference material – typical domestic C 130 material, mechanical strength was somewhat lower. Carried out investigations proved that resistance of the investigated material to the ageing degradation process – during long term operation – also decreased. The improvement of technological parameters and the reduction in the number of defective elements occurred simultaneously with some decrease in the operational parameters of the material. To restore their initial high level, further work is needed to optimize the raw material composition of the porcelain.

6

Microstructure and Degree of Degradation of ZnO Varistors in Surge Arresters Due to Operation

Papliński P., Wańkowicz J., Ranachowski P., Ranachowski Z.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 3

1267--1273

EN

The paper presents the test results for the microstructure of ZnO varistors comprising high voltage gapless surge arresters. The tests were performed on varistors produced in different periods and by various manufacturers. The research was inspired by different characteristics of changes in values of current flowing through surge arresters as a function of changes in values of system voltage in a 220 kV substation, and the temperature in a multi-year cycle. Furthermore, the effects of varistor microstructure degradation following a failure of an unsealed surge arrester were investigated. The results provided the grounds for assessment of ZnO varistor microstructure parameters in terms of their durability and resistance to degradation processes.

7

Examination of the Properties of Samples from Glass-Epoxy Core Rods for Composite Insulators Subjected to DC High Voltage

Wieczorek K., Jaroszewski M., Ranachowski P., Ranachowski Z.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 3

1281--1286

EN

This article presents the results of an examination performed on a set of samples of glass-epoxy core rods used in composite insulators with silicone rubber housings. The goal of the examination was to test the aging resistance of the core material when exposed to Direct Current (DC) high voltage. Long term exposure of a glass-epoxy core rod to DC high voltage may lead to the gradual degradation of its mechanical properties due to the ion migrations. Electrolysis of the core material (glass fiber) may cause electrical breakdown of the insulators and consequently lead to a major failure. After being aged for 6000 hours under DC high voltage, the samples were subjected to microscopic analysis. Their chemical composition was also examined using Raman spectroscopy and their dielectric losses and conductance in the broad range of frequencies were tested using dielectric spectroscopy.

8

Microstructural characterization of cellulose fibres in reinforced cement boards

Schabowicz K., Jóźwiak-Niedźwiedzka D., Ranachowski Z., Kudela S., Dvorak T.

Archives of Civil and Mechanical Engineering

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2018

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Vol. 18, no. 4

1068--1078

EN

The microscopic analysis of the different cellulose fibre cement composites is presented. The observations of the fibres in optical microscope in transmitted light and in scanning electron microscope are described. The micro computed tomography (micro-CT) and SEM were used to determine the distribution of the fibres in the matrix. The investigated fibre cement boards were produced by extrusion process and panels were cured in natural conditions. The main goal of the research was application of different microscopic methods to analyze the fibres distribution as a result of a different methods of their production. Micro-CT was used for 3D visualization of fibres distribution in three different fibre cement boards. It was possible to determine the average diameter of the fibres and their concentration using the high-resolution mode of micro-CT scanning procedure. Finally, a procedure which can be applied as a useful tool for analysis of the different procedures used in production of fibre cement boards is described. This procedure can be successfully used in the quality control system of cellulose fibre distribution in cement composites.

9

The Application of Acoustic Emission and Artificial Neural Networks in an Analysis of Kinetics in the Phase Transformation of Tool Steel During Austempering

Łazarska M., Woźniak T. Z., Ranachowski Z., Ranachowski P., Trafarski A.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 2A

603--609

EN

During the course of the study it involved tool steel C105U was used. The steel was austempered at temperatures of 130°C, 160°C and 180°C respectively. Methods of acoustic emission (AE) were used to investigate the resulting effects associated with transformations and a large number of AE events were registered. Neural networks were applied to analyse these phenomena. In the tested signal, three groups of events were identified of: high, medium and low energy. The average spectral characteristics enabled the power of the signal spectrum to be determined. After completing the process, the results were compiled in the form of diagrams of the relationship of the AE incidence frequency as a function of time. Based on the results, it was found that in the austempering of tool steel, in the first stage of transformation midrib morphology is formed. Midrib is a twinned thin plate martensite. In the 2nd stage of transformation, the intensity of the generation of medium energy events indicates the occurrence of bainite initialised by martensite. The obtained graphic of AE characteristics of tool steel austempering allow conclusions to be drawn about the kinetics and the mechanism of this transformation.

10

Study of Composite Insulator Sheds Subjected to Wheel Test

Mackiewicz M., Mikulski J. L., Wańkowicz J., Kucharski S., Ranachowski P., Ranachowski Z.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 2A

679--686

EN

The paper presents investigation of the properties of the surface and the material stiffness – flexibility of series of samples taken from the sheds of the composite insulators. The insulators were previously subjected to wheel test. The wheel test and 1000 h salt fog test are regarded as alternative examination of the material resistance to the effects of electrical surface discharges. There were investigated two series of the samples of the composite insulators sheds. Examined specimens, made of HTV silicone rubber, were taken from the sheds of medium-voltage composite insulators of two different manufacturers. Insulators of both types passed the 1000 h salt fog test without reservation. Meanwhile, the wheel test can provide a basis for better distinguishing between physical properties of the tested materials. In the case of the insulators of one of the manufacturers the wheel test result was negative. Cross puncture effect of the sheds took place in several places. In addition, sheds were covered with dark coating of varying thicknesses. The results of the study indicated a significantly stronger influence of electrical and temperature factors on the sheds under investigations during the wheel test than in the case of the 1000 h salt fog test. It can be stated that these tests cannot be considered as alternative and it seems that wheel test enables better distinguishing between properties of the materials.

11

Statistical Assessment of the Microstructure of Barite Aggregate from Different Deposits Using X-Ray Microtomography and Optical Microscopy

Żołek N., Ranachowski Z., Ranachowski P., Jóźwiak-Niedźwiedzka D., Kudela S. jr., Dvorak T.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 2A

697--702

EN

Two different barite ore (barium sulfate BaSO4) specimens from different localizations were tested and described in this paper. Analysis of the microstructure was performed on polished sections, and on thin sections using X-ray microtomography (micro-CT), and optical microscopy (MO). Microtomography allowed obtaining three-dimensional images of the barite aggregate specimens. In the tomograms, the spatial distribution of the other polluting phases, empty space as well as cracks, pores, and voids – that exceeded ten micrometers of diameter-were possible to visualize. Also, the micro-CT allowed distinguishing between minerals of different density, like SiO2 and BaSO4. Images obtained and analyzed on thin sections with various methods using the optical microscopy in transmitted light delivered additional information on the aggregate microstructure, i.e. allow for estimation of the different kinds of inclusions (like the different density of the minerals) in the investigated specimens. Above methods, which were used in the tests, completed each another in order to supply a set of information on inclusions’ distribution and to present the important differences of the barite aggregate specimens microstructure.

12

Badania ultradźwiękowe płyt włóknisto-cementowych

Dębowski T., Lewandowski M., Mackiewicz S., Ranachowski Z., Schabowicz K.

Przegląd Spawalnictwa

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2016

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R. 88, nr 10

69--71

PL

W artykule przedstawiona została możliwość lokalizacji delaminacji w płycie włóknisto-cementowej za pomocą specjalnie do tego celu skonstruowanego urządzenia wykorzystującego metodę ultradźwiękową i fale podłużne. Przeprowadzono badania na trzech rodzajach płyt. Stwierdzono, że proponowana metoda diagnostyczna umożliwia wykrywanie lokalnych nieciągłości, np. obszarów o obniżonej zwartości, czy delaminacji w płytach włóknisto-cementowych na obszarze średnicy wiązki metodą estymacji prędkości fali ultradźwiękowej. Zaletami metody są niewielkie wymiary urządzenia i krótki czas badania.

EN

This article presents the possibility of delamination location in the fiber-cement board using a specially-designed device operating on the principle of ultrasonic method and measuring of longitudinal waves velocity. Studies were carried out on three types of board. It was found that the proposed diagnostic method allows detection of local discontinuities, eg. the areas of reduced compactness, or delamination in fiber-cement boards in the area of the beam diameter by an estimation velocity of ultrasonic waves. The advantages of the method are: small dimensions of the device and short duration of the study.

13

Monitorowanie parametrów termicznych procesu twardnienia betonów osłonowych

Jaskulski R., Glinicki M. A., Dąbrowski M., Ranachowski Z., Sobczak M.

Czasopismo Inżynierii Lądowej, Środowiska i Architektury / Journal of Civil Engineering, Environment and Architecture

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2016

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z. 63, nr 1/I

123--132

PL

W artykule przedstawiono wyniki badań parametrów termicznych procesu twardnienia mieszanek betonowych, z których dwie wykonano z wykorzystaniem kruszyw stosowanych w produkcji betonów osłonowych (kruszywo magnetytowe oraz serpentynitowe), a trzecią, referencyjną, z wykorzystaniem kruszywa amfibolitowego. Na podstawie analizy dokonanych pomiarów temperatury wyznaczono parametry procesu twardnienia betonu (m.in. maksymalny przyrost temperatury, maksymalny gradient i in.). Jednocześnie rozwiązując numerycznie tzw. zagadnienie odwrotne wyznaczono parametry cieplne betonu w trakcie pierwszych 72 godzin twardnienia. Tą samą metodą wyznaczono również wartości funkcji źródła ciepła, a następnie na jej podstawie oszacowano ilość ciepła wydzieloną w procesie hydratacji cementu. Uzyskano dobrą jakościową zgodność postaci funkcji źródła ciepła oraz wykresów zmian temperatury w mieszankach. W toku analiz uzyskanych wyników wyraźnie zaznaczył się wpływ zróżnicowania parametrów cieplnych zastosowanych kruszyw. W przypadku mieszanki z kruszywem serpentynitowym dały się także zauważyć istotne różnice w przebiegu przyrostu temperatury (opóźnienie) w stosunku do pozostałych mieszanek.

EN

The article presents the results of thermal parameters monitoring of the hardening process of three concrete mixtures. Two of them were prepared using an aggregate used in the manufacturing of shielding concretes (magnetite and serpentine aggregate) and the third one was the reference one prepared with amphibolite aggregate. Thermal parameters of the hardening process of the concrete were determined on the basis of the measured temperature changes. On the same basis by means of numerical solution of the inverse problem the thermal parameters of concrete mixtures during 72 h of hardening were determined. Using the same method the heat source function values were determined and on its basis the total quantity of heat released during hydration of cement was estimated. Good compliance of the release functions and the charts of temperature changes in mixtures was obtained. The differences due to different thermal parameters of the aggregates were clearly marked. In the case of mixture with serpentine aggregate significant differences in the course of temperature increase (delay) relative to the other mixtures were observed.

14

Study of factors determinant of siliceous electrical porcelain resistance to structural degradation

Ranachowski P., Ranachowski Z., Kudela Jr. S., Pawełek A., Piątkowski A.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 3

1489--1496

EN

The subject of this study was investigation of the factors that have a decisive influence on the resistance of siliceous porcelain to degradation processes. There was tested material C 110 type, which is widely used for the production of low-voltage (LV) elements such as insulators and bushings. On the basis of mechanical-acoustic and microscopic research of small-sized samples, which were subjected to compression, there were distinguished successive stages of degradation of the material structure. In the authors* opinion, they have a reference to the ageing process, taking place during many years of work under operating conditions. Thus, it was possible to assess the structural factors that determine the durability and reliability of LV electroinsulating elements. The results were related to electrical aluminous porcelains.

15

Plastic Instabilities Induced by the Portevin - Le Châtelier Effect and Fracture Character of Deformed Mg-Li Alloys Investigated Using the Acoustic Emission Method

Pawełek A., Piątkowski A., Wajda W., Skuza W., Tarasek A., Ranachowski Z., Ranachowski P., Ozgowicz W., Kúdela Jr., Kúdela S.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 2A

897--904

EN

The results of the investigation of both mechanical and acoustic emission (AE) behaviors of Mg4Li5Al and Mg4Li4Zn alloys subjected to compression and tensile tests at room temperature are compared with the test results obtained using the same alloys and loading scheme but at elevated temperatures. The main aim of the paper is to investigate, to determine and to explain the relation between plastic flow instabilities and the fracture characteristics. There are discussed the possible influence of the factors related with enhanced internal stresses such as: segregation of precipitates along grain boundaries, interaction of solute atoms with mobile dislocations (Cottrell atmospheres) as well as dislocation pile-ups which may lead to the microcracks formation due to the creation of very high stress concentration at grain boundaries. The results show that the plastic flow discontinuities are related to the Portevin-Le Châtelier phenomenon (PL effect) and they are correlated with the generation of characteristic AE pulse trains. The fractography of broken samples was analyzed on the basis of light (optical), TEM and SEM images.

16

The Determination Of Diffusive Tortuosity In Concrete Specimens Using X-Ray Microtomography

Ranachowski Z., Jóźwiak-Niedźwiedzka D., Ranachowski P., Dąbrowski M., Kudela Jr. S., Dvorak T.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 2A

1115--1119

EN

The paper presents a method of pore connectivity analysis applied to specimens of cement based composites differing in water to cement ratio. The method employed X-ray microtomography (micro-CT). Microtomography supplied digitized three-dimensional radiographs of small concrete specimens. The data derived from the radiographs were applied as an input into the application based on the algorithm called ‘random walk simulation’. As the result a parameter called diffusive tortuosity was established and compared with estimated porosity of examined specimens.

PL

Artykuł prezentuje metodę wyznaczania parametru charakteryzującego intensywność połączeń mikroporów w zastosowaniu do próbek kompozytów z matrycą cementową, różniących się stosunkiem wodnocementowym. Metoda bazuje na wynikach badań z zastosowaniem mikrotomograﬁi rentgenowskiej. Analizowano zdigitizowane zestawy danych, opisujące trójwymiarową reprezentację mikrostruktury niewielkich próbek wykonanych z betonu. Przygotowane w ten sposób skany mikrostruktury zastosowano jako dane wejściowe wprowadzone do oprogramowania wykorzystujacego algorytm ‘przypadkowo migrujących cząstek wirtualnych’. W ten sposób wyznaczono parametr mikrostruktury znany jako krętość dyfuzyjna. Parametr ten porównano z porowatością obserwowaną wyznaczoną dla zbadanych próbek przy wykorzystaniu analizy jasności voxeli w analizowanych próbkach.

17

Light alloys for application as engine parts – comparison of properties of three materials

Ranachowski Z., Pawełek A., Drzymała P., Bonarski J., Lewandowski M., Ozgowicz W.

Zeszyty Naukowe / Akademia Morska w Szczecinie

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2014

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nr 39 (111)

128--132

EN

This paper discusses the mechanical properties, microstructure and crystallographic texture of light alloys made on the base of aluminium, magnesium and lithium. An acoustic emission (AE) technique was applied to detect the moment of twinning or slip activation during compression and channel – die tests to extend the comprehension on the nature of the plastic deformation processes occurring in the investigated alloys.

18

Influence of microstructure on the properties of siliceous electrical porcelain

Ranachowski P., Rejmund F., Ranachowski Z., Pawełek A., Piątkowski A., Kudela Jr. S.

Przegląd Elektrotechniczny

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2014

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R. 90, nr 10

110-113

EN

The paper presents the microscopic and mechanoacoustic study of degradation processes of the porcelain material C 110 type. Smallsized samples, derived from the low voltage insulator, were subjected to a slow, quasi-static compression, with simultaneous recording of acoustic emission descriptors. There were distinguished consecutive stages of the material degradation. Obtained results were compared with the images of the microstructure of low-voltage insulator materials after many years of operation. On this basis, there were distinguished the factors determinant of the short-term strength of porcelain and its resistance to ageing processes under operating conditions.

PL

W pracy przedstawiono mikroskopowe oraz mechanoakustyczne badania procesów degradacji w tworzywie porcelanowym rodzaju C 110. Próbki małogabarytowe, pochodzące z elementu elektroizolacyjnego niskiego napięcia, poddawane były powolnemu, quasi-statycznemu ściskaniu, z jednoczesną rejestracją deskryptorów emisji akustycznej. Na podstawie badań mikroskopowych ściskanych próbek wyróżniono etapy degradacji materiału. Wyniki konfrontowano z obrazami mikrostruktury tworzywa izolatorów niskonapięciowych po wieloletniej eksploatacji. Wyróżniono czynniki mające wpływ na wytrzymałość krótkotrwałą oraz odporność tworzywa na starzenie się w warunkach eksploatacyjnych.

19

The Portevin –Le Chatelier Effect and Acoustic Emission of Plastic Deformation CuZn30 Monocrystals

Ozgowicz W., Grzegorczyk B., Pawełek A., Piątkowski A., Ranachowski Z.

Archives of Metallurgy and Materials

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2014

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Vol. 59, iss. 1

183--188

EN

The paper presents the investigation of the relation between the acoustic emission (AE) and instability of plastic deformation type Portevin-Le Chatelier (PLC) of single-phase brass CuZn30 monocrystals with crystallographical orientation [13 9]. The monocrystals have been investigated applying the method of free compression at a constant strain rate and the temperature within the range from 200°C to 400°C, simultaneously recording PLC phenomenon by means of acoustic emission. During hot axial compression tests the correlation between work-hardening curves σ - ε, which display PLC effect and characteristic of acoustic emission signals has been found. Moreover, it was proved that in the range of the PLC effect, the acoustic signal is an impulse a character of cyclic repeatability, distinctly correlated qualitatively with the stress oscillations on the curves σ - ε. The analysis of the obtained results leads to the conclusion that in the tested monocrystals the effect PLC is probably controlled by complex processes similar to the phenomenon of dynamic strain ageing (DSA), which are described by diffusion models.

PL

Streszczenie W pracy badano zależność między emisją akustyczną (EA), a niestabilnością odkształcenia plastycznego typu Portevin Le Chatelier monokryształów jednofazowego mosiądzu CuZn30 o orientacji krystalograficznej [13 9]. Monokryształy poddano próbie swobodnego ściskania przy stałej prędkości odkształcenia w zakresie temperatury od 200°C do 400°C stosując jednocześnie pomiar emisji akustycznej. Określono zależność pomiędzy przebiegiem krzywych umocnienia σ - ε wykazujących efekt PLC. a charakterystyką sygnałów emisji akustycznej generowanych w badanej próbie ściskania jednoosiowego. Stwierdzono, że w zakresie występowania efektu PLC podczas próby ściskania, sygnał EA ma charakter impulsu cyklicznego, wyraźnie skorelowany jakościowo z oscylacjami naprężeń na krzywych σ - ε. Analiza uzyskanych wyników pozwala przypuszczać, że w badanych monokryształach efekt PLC jest kontrolowany prawdopodobnie przez złożone procesy podobne do zjawisk starzenia dynamicznego po zgniocie (DSA), które są opisane modelami dyfuzyjnymi.

20

The Application of Neural Networks for Studying Phase Transformation by the Method of Acoustic Emission in Bearing Steel

Woźniak T. Z., Ranachowski Z., Ranachowski P., Ozgowicz W., Trafarski A.

Archives of Metallurgy and Materials

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2014

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Vol. 59, iss. 4

1705--1712

EN

The research was carried out on steel 100CrMnSi6-4 under isothermal austempering resulting in forming the duplex structure: martensitic and bainitic. The kinetics of transformation was controlled by the acoustic emission method. Complex phase transformations caused by segregation and carbide banding occur at the low-temperature heat treatment of bearing steel. At the temperature close to Ms, a certain temperature range occurs where an effect of the first product of prior athermal martensite on the bainitic transformation can be observed. In the registered signal about 15 million various events were registered. There were considered three types of acoustic emission events (of high, medium and low energy), with relatively wide sections and with different spectral characteristics. It was found that the method of acoustic emission complemented by the application of neural networks is a sensitive tool to identify the kinetics of bainitic transformation and to show the interaction between martensitic and bainitic transformations.

PL

Badania realizowano na stali 100CrMnSi6-4 poddanej hartowaniu izotermicznemu, prowadzacemu do utworzenia struktury duplex: martenzytyczno-bainitycznej. Kinetykę przemian kontrolowano metodą emisji akustycznej. Przy niskotemperaturowej obróbce cieplnej stali łożyskowej występują złożone przemiany fazowe spowodowane segregacją i pasmowością węglików. W temperaturze zbliżonej do Ms, występuje pewien zakres temperatury, gdzie zaznacza się oddziaływanie wcześniejszego produktu przemiany martenzytycznej na przemianę bainityczną. W zarejestrowanym sygnale zarejestrowano około 15 milionów różnych zdarzeń. Uwzgledniono trzy rodzaje zdarzeń emisji akustycznej (o wysokiej, średniej i niskiej energii) o względnie szerokich przedziałach, o różnej charakterystyce widmowej. Stwierdzono, że metoda emisji akustycznej uzupełniona o zastosowanie sieci neuronowych jest czułym narzędziem do identyfikacji kinetyki przemiany bainitycznej oraz oddziaływania przemiany martenzytycznej na przemianę bainityczną.