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1

Influence hot plastic deformation on the structure and properties of carbon steel of the railway wheel

Vakulenko Igor, Plitchenko Sergey, Bolotova Dariy, Asgarov Khangardash

Zeszyty Naukowe. Transport / Politechnika Śląska

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2023

|

z. 121

257--266

EN

The study is devoted to the explanation of the influence of hot plastic deformation on the properties of railway wheels. The shape of individual elements of the wheel provides for a different degree of hot compression, which determines the mechanism for the development of the recrystallization at austenite. With a decrease in the degree of the hot deformation, a certain proportion of grains with a low energy of linear stretching are formed in austenite. As a result, of the low mobility of such boundaries, the likelihood of preservation of part of the substructural state of the austenite increases, which should affect the formation of a colony of perlite during the cooling of the carbon steel. Against background preservation and a dependence of strength properties on the dispersion of the pearlite colony, the appearance in austenite of grain boundaries with a low energy of linear tension leads to a qualitative change in the plastic properties of railway wheel steel. The increase in plasticity of carbon steel with an increase in dispersion of the pearlite colony is due to a decrease in the effect of solid solution hardening and an increase in the role of the ferrite-cementite interface in the development processes of strain hardening carbon steel. The results obtained can be useful for improving the technology of manufacturing all-rolled railway wheels.

2

Staliwo stopowe wysokomanganowe w zastosowaniach na odlewane elementy infrastruktury kolejowej

Wróbel Tomasz, Bartocha Dariusz, Jezierski Jan, Sobula Sebastian, Kostrzewa Krzysztof, Feliks Edward

Stal, Metale & Nowe Technologie

|

2023

|

nr 1-2

30--34

PL

W publikacji przedstawiono charakterystykę staliwa stopowego wysokomanganowego, potocznie określanego mianem staliwa Hadfielda. Staliwa z tej grupy w warunkach wzrostu ciśnienia lub obciążenia, np. w wyniku uderzenia, wykazują dużą skłonność do tzw. umocnienia zgniotem, objawiającego się zwiększeniem powierzchniowej twardości i odporności na zużycie przy zachowaniu ciągliwości rdzenia.

EN

The paper presents the characteristics of a high-manganese alloy cast steel, commonly referred to as Hadfield cast steel. Cast steels of this group demonstrate a high tendency to the so-called strain hardening under the conditions of pressure or load increase, e.g. as a result of an impact, which is manifested by an increase in surface hardness and wear resistance while maintaining the ductility of the core. This is decisive for the applicability of a high-manganese cast steel for the castings of hammers and liners for coal mills and other mills, crusher cones, working elements of construction machines as well as cast elements of turnouts. In particular, the paper presents the chemical composition and usable properties of a high- -manganese cast steel intended for use in railway infrastructure as well as the characteristics of its microstructure finally shaped by heat treatment.

3

Effect of various factors on the measurement error of structural components of machine parts materials microhardness using computer vision methods

Vlasovets Vitaliy, Vlasenko Tatiana, Kovalyshyn Stepan, Kovalyshyn Olesy, Kovalyshyn Oleg, Kurpaska Sławomir, Kiełbasa Paweł, Bilovod Oleksandra, Shulga Lyudmila

Przegląd Elektrotechniczny

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2023

|

R. 99, nr 1

323--329

EN

To assess the causes of failure of parts in operation, it is often necessary to assess the degradation of the structural and phase composition of the material and determine the cause of its change. Microhardness test is used to evaluate the mechanical properties of microvolumes of the material. Microhardness of structural components of steels and cast irons (armco iron ferrite, austenitic component of steel 12Х18Н10Т and cementite of centrifugally cast chrome-nickel cast iron (cast coating Ø910 mm)) was determined by restored four-sided pyramid impression with a square base and a top angle of 136±1. The paper evaluates the influence of the main factors on the micro-hardness error of ferritic, austenitic and carbide component of steels and cast irons: the amount and speed of the indenter load, the stiffness of the substrate, the field of distribution of plastic deformations around the impression, the quality of the surface preparation, the influence of grain boundaries and the relaxation of the impression shape over time. The main factors affecting the accuracy of measurements by the reconstructed impression method have been determined for each of the investigated phases: ferrite, austenite, and cementite.

PL

Aby ocenić przyczyny awarii części w eksploatacji, często konieczna jest ocena degradacji składu strukturalnego i fazowego materiału oraz określenie przyczyny jego zmiany. Do oceny właściwości mechanicznych mikroobjętości materiału stosuje się test mi-rotwardości. Mikrotwardość składników strukturalnych stali i żeliwa (ferryt żelaza armco, austenityczny składnik stali 12Х18Н10Т i cementyt odśrodkowo odlewanego żeliwa chromowo-niklowego (powłoka odlewu Ø910 mm)) określono przez przywrócony wycisk piramidy czterobocznej o podstawie kwadratowej i kącie wierzchołkowym 136±1. W pracy oceniono wpływ głównych czynników na błąd mikrotwardości ferrytycznego, austenitycznego i węglikowego składnika stali i żeliwa: wielkości i prędkości obciążenia wgłębnika, sztywności podłoża, pola rozkładu odkształceń plastycznych wokół wycisku, jakości przygotowania powierzchni, wpływu granic ziaren oraz relaksacji kształtu wycisku w czasie. Określono główne czynniki wpływające na dokładność pomiarów metodą zrekonstruowanego wycisku dla każdej z badanych faz: ferrytu, austenitu i cementytu.

4

Effects of the thermomechanical treatment on the microstructure and mechanical properties of ferrite–martensite dual phase steel

Ha M. T., Pham M. K., Nguyen H. H.

Archives of Materials Science and Engineering

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2023

|

Vol. 124, nr 2

49--55

EN

Purpose: The study aims to investigate the effects of thermomechanical treatment, including tempering and hot–rolling, on the microstructure and mechanical properties of ferrite–martensite dual phase steel. Design/methodology/approach: The initial steel billet was a hypoeutectoid steel, which was annealed at 1000ºC, then hot–rolled at 920ºC, followed by austenitisation at various temperatures (730, 770, 800, and 830ºC), and finally quenched to obtain ferrite–martensite dual phase steel. X-ray diffractometer and optical microscopy investigated the microstructure and grain size of the dual-phase steel. Mechanical properties such as hardness, elongation, and tensile strength were also examined. Findings: The grain size decreased with increasing elongation percentage and remained constant after an elongation of 30%. The martensite/ferrite phase ratio increased with higher tempering temperatures. The hardness, elongation, and tensile strength reached a maximum when the tempering temperature was 800ºC. Research limitations/implications: Future studies could consider the effect of hot–rolling temperature or cold-rolling. Practical implications: The study proposes a straightforward and efficient thermomechanical treatment process to transform hypereutectoid steel into ferrite-martensite dual-phase dual- phase steel with improved mechanical properties. Originality/value: The study reveals the contributions of grain size and the martensite/ferrite ratio to the mechanical properties of ferrite–martensite dual steel through thermomechanical treatment.

5

Modelowanie struktury i własności mechanicznych stali mikrostopowych

Adrian Henryk, Marynowski Przemysław

Stal, Metale & Nowe Technologie

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2021

|

nr 1-2

61--67

PL

Własności mechaniczne stali mikrostopowych zależą od zawartości i wielkości wydzieleń węglikoazotków, które tworzą mikrododatki takich pierwiastków jak: Ti, Nb, V, wprowadzane w ilościach nieprzekraczających 0,1%. W pracy zaprezentowano program komputerowy do obliczania zawartości i wielkości wydzieleń węglikoazotku M(C,N) oraz składu chemicznego austenitu przy danej temperaturze austenityzowania na podstawie składu chemicznego stali i warunków obróbki cieplnej. Przeprowadzono analizę wpływu składu chemicznego stali na parametry powstających w warunkach izotermicznych wydzieleń węglikoazotków M(C,N) oraz na efekt umocnienia wydzieleniowego z wykorzystaniem programu komputerowego. Zaprezentowano obrazy symulowanej mikrostruktury zawierającej wydzielenia.

EN

The mechanical properties of microalloyed steels depend on the content and size of carbonitride precipitates, which form micro-additions of such elements as Ti, Nb, and V, introduced in amounts not exceeding 0.1%. The paper presents a computer programme for calculating the content and size of M(C,N) carbonitride precipitates and the chemical composition of austenite at a given austenitizing temperature based on the chemical composition of steel and heat treatment conditions. An analysis of the influence of the chemical composition of steel on the parameters of M(C,N) carbonitride precipitates formed in isothermal conditions and on the effect of precipitation strengthening with the use of the computer programme was carried out. The images of simulated microstructure containing the precipitates are presented.

6

Mechanical stability of retained austenite in aluminum-containing medium-Mn steel deformed at different temperatures

Kozłowska Aleksandra, Radwański Krzysztof, Matus Krzysztof, Samek Ludovic, Grajcar Adam

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 1

324--338

EN

The thermal and mechanical stabilities of retained austenite in aluminum-containing medium-Mn 0.16C–4.7Mn–1.6Al–0.2Si sheet steel were investigated. The strain-induced martensitic transformation in Mn TRIP steel was studied at different temperatures. Static tensile tests were carried out at the temperature ranging from − 60 to 200 °C. The tests allowed to study the influence of the temperature on austenite-to-martensite transformation kinetics. The interrupted tensile tests and corresponding X-ray measurements of retained austenite amount were performed to determine the mechanical stability of retained austenite using the Sugimoto model. The microstructure changes were investigated using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. Observed results reflected the effects of deformation temperature on the mechanical stability of retained austenite and the corresponding response of this phase to martensitic transformation. It was found that an increase in the deformation temperature resulted in the reduced intensity of the TRIP effect due to the higher mechanical stability of retained austenite. At the highest deformation temperature (200 °C), the evidence of thermally activated processes affecting the mechanical behavior was identified.

7

Experimental and modelling study of the grain refinement of Fe-30wt%Ni-Nb austenite model alloy subjected to severe plastic deformation process

Svyetlichnyy D. S., Majta J., Kuziak R., Muszka K.

Archives of Civil and Mechanical Engineering

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2021

|

Vol. 21, no. 1

339--352

EN

This study addresses some aspects regarding a computer modelling based on three-dimensional Frontal Cellular Automata (FCA) for the simulation of ultrafine-grained (UFG) microstructure development in purpose-designed microalloyed austenite model alloy i.e. FCC structure. Proposed in the present study model is a step forward towards understanding the deformation and microstructure development mechanisms occurring during severe plastic deformation (SPD) processes with high accumulation of the plastic deformation effects in FCC structures. The analysed microalloyed austenite microstructures were developed due to SPD effects. Using the proposed computer model, based on three-dimensional FCA it has been shown that it is possible to predict some characteristics of the FCC microstructures such as the grain size and the distribution of the boundaries misorientation angle. These abilities were proved by the qualitative and quantitative comparisons of the modelling and SEM/EBSD results. The capabilities of the proposed model were tested using experimental results of the wire drawing processes. The paper presents the new original results of experimental studies of multi-staged MaxStrain technology with the microscopic investigation. Basing on data obtained from these studies, the dependencies of the evolution of grain structure and misorientation angle on the accumulative strain and cycle number were obtained in a form of approximation equations. The equations were implemented into the CA model, and MaxStrain technology was simulated. Comparison of the results obtained in experimental studies and simulations shows a satisfactory agreement. Industrial verification of the developed model as well shows a satisfactory agreement.

8

The calculation of stress intensity factor steel of railway wheels

Vakulenko Igor, Proydak Svetlana, Askerov Hangardas

Zeszyty Naukowe. Transport / Politechnika Śląska

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2020

|

z. 109

187--193

EN

From an analysis of the dependence complex of carbon steel properties on structural parameters, it was found that for an isostructural state, the influence of austenite grain size on impact strength exceeds the dependence on carbon content. As a result of explaining correlation relationships between individual mechanical characteristics, to evaluate critical stress intensity factor, a relationship is proposed based on the use of impact strength. The proportionality coefficient in proposed dependence is determined by ratio of elongation to narrowing at tensile test.

9

Kumar Sanjeev, Pandey Chandan, Goyal Amit

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 3

506--532

EN

This paper investigates the metallurgical behavior and mechanical properties of the P91 steel welds joint. The joint of heat-resistant P91 steel has been welded by the gas tungsten arc welding (GTAW) process using the dissimilar Inconel grade 617 filler. The P91 welds joints have been subjected to varying heat treatment regimes in the temperature range of 650–810 °C for 2 h. The normalizing-based tempering was also performed for the welded joint. The weld fusion zone (WFZ) with austenitic structure and heat-affected zones (HAZs) with martensitic structure was characterized using the optical microscope and scanning electron microscope (SEM). The detailed characterization of the weld metal and HAZ interface has also been performed for as-welded and post-weld heat treatment (PWHT) conditions. For mechanical properties of the welds joint, tensile testing and hardness testing were performed. The relationship between mechanical behavior and microstructure of the welded joint has been evaluated for as-welded and heat treatment conditions. The microstructure studies revealed the formation of an unmixed zone (UZ) close to the fusion line, and it was characterized as peninsula and island. The WFZ showed the complete austenitic mode of the solidification and revealed the austenitic structure with cellular and equiaxed grains in the center of the weld metal. The columnar and cellular dendrites were seen near the boat fusion line, i.e., interface of the weld metal and HAZ. The soft δ ferrite patches were observed near the fusion line in the area of HAZ and remain undissolved up to tempering temperature of 810 °C (PW 3). The dissolution of the ferrite patches was noticed for PW 4. The maximum and minimum tensile strength of the welds joint was measured 731 MPa and 502 MPa for PW 3 and PW 2, respectively. A uniform hardness variation in the transverse direction of the welded joint was observed for PW 3 and PW 4 conditions. The optimum combination of strength and ductility was obtained for the PW 3 condition.

10

Physical simulation and dilatometric study of double-step heat treatment of medium-Mn steel

Skowronek A., Morawiec M., Ruiz-Jimenez V., Garcia-Mateo C., Grajcar A.

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 4

578--588

EN

The work addresses physical simulation and dilatometric study of one-step and double-step heat treatments of medium-Mn steel designed for automotive sheets. The conventional one-step isothermal bainitic transformation was applied as the reference heat treatment. The newly implemented heat treatment consisted of isothermal holding in a bainitic region followed by additional holding of the material at reduced temperature also in the bainitic range. This step was added to refine the microstructure, which led to the stabilization of the retained austenite. Calculations of equilibrium state and non-equilibrium cooling and simulations of the developed thermal cycles were performed using the thermodynamic JMatPro software. The physical simulations of the heat treatment were performed in the dilatometer. The obtained samples were subjected to microscopic observations using light and SEM microscopy. One- and two-step heat treatments allowed to obtain bainitic structures with high contents of retained austenite. Lowering the temperature of one-step isothermal holding resulted in the bainite refinement and adjacent retained austenite. The increased Mn content in steel increased its susceptibility to form coalesced bainite resulting in the partial formation of thicker plates despite a decrease in a process temperature.

11

Wpływ odkształcenia plastycznego na przemiany austenitu przechłodzonego stali mikrostopowej

Opiela Marek, Wojtacha Anna

Stal, Metale & Nowe Technologie

|

2019

|

nr 1-2

74--80

PL

W pracy przedstawiono wyniki badań wpływu odkształcenia plastycznego oraz szybkości chłodzenia na strukturę i postać krzywych przemian fazowych austenitu przechłodzonego stali mikrostopowej z Nb, Ti, V i B. Wyznaczono krzywe przemian austenitu przechłodzonego nieodkształconego plastycznie (CTPc) oraz odkształconego plastycznie (OCTPc).

EN

The aim of the paper is to investigate the influence of plastic deformation and cooling rate on the structure and shape of the supercooled austenite transformations diagrams of a Nb-Ti-V-B microalloyed steel. The CCT diagrams of underformed and plastically deformed supercooled austenite were developed. The plastic deformation of steel prior to the start of phase transformations results in a sharp acceleration of pearlitic transformation and a slight translation of bainitic transformation towards shorter times. The elaborated curves of supercooled austenite transformations of the steel create possibilities to develop an industrial technology for thermomechanically treated forgings of high mechanical properties.

12

Fatigue life improvement on 20MnCr5 steel through surface modification for auto transmission application

Srinivasan Ramesh, Natarajan S., Sivakumar V. J.

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 2

360--374

EN

This research represents a unique approach in improving the fatigue life of 20MnCr5 (89–91 HR15N hardness) shafts which were surface treated through gas carburizing process in a sealed quench furnace followed by double tempering. Crack initiation on 20MNCr5 transmission shafts always occurs at the end of spline location (Location X), propagates longitudinally and finally ruptures at stem location. This was confirmed through optical microscope and SEM (make:Jeol) images. The fatigue experiments were carried out at room temperature in 11,500 Nm torque test machine (Model – MTS-663-144-01). The torque test was carried-out by applying a fully reversed cyclic load with the frequency of 5 Hz for the torsional load of ±3000 Nm. Effect of double tempering, surface roughness, carbon case depth, Microstructure such as retained austenite and non-martensitic transformation products (NMTP) have been investigated in this research. The outcome of the research shows that increase in case depth (CD) (out of increased gas carburising time) resulting in increased inter-granular oxidation (IGO) and NMTP in its microstructure. The presence of retained austenite on the surface of the shaft has not yielded any remarkable improvement in fatigue life of the shaft. Presence of tempered martensite with lesser percentage of retained austenite on the surface improved the fatigue life drastically from 12,000 cycles to greater than 35,000 cycles at high torque load of ±3000 Nm.

13

Niskotemperaturowe nawęglanie gazowe stali austenitycznej typu X5CrNi18-10 aktywowanej cienką powłoką żelaza

Żółciak T., Przywóski A.

Inżynieria Powierzchni

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2018

|

nr 1

50--60

PL

W pracy badano skuteczność aktywacji stali nierdzewnej X5CrNi18-10 za pomocą cienkiej powłoki żelaza w zastosowaniu do niskotemperaturowego nawęglania oraz przydatność generatorowej atmosfery endotermicznej do tego procesu. W celu aktywacji powierzchni stali nakładano na nią elektrolitycznie bezprądowo powłokę żelaza o grubości 1–2 μm. Nawęglanie przeprowadzano w temperaturach 450–500oC w atmosferach na bazie generatorowej atmosfery endotermicznej z dodatkiem azotu lub wodoru. Modyfikacja powłoki przez dodanie kilku procent siarki do żelaza spowodowała zmniejszenie rozrzutu twardości na powierzchni, a pojawiająca się sadza wykazywała luźne powiązanie z powłoką. Alternatywna aktywacja za pomocą krótkotrwałego tlenoazotowania z następującym po nim wyżarzaniem dyfuzyjnym sprzyjała wzrostowi twardości na powierzchni i zmniejszeniu jej rozrzutu po nawęglaniu. Po nawęglaniu w endogazie stali X5CrNi18-10 w temperaturze 470oC w czasie 30 h uzyskano warstwę nawęgloną o grubości ok. 35 μm i twardość na powierzchni ok. 1150 HV0,05. Obniżenie temperatury nawęglania o 20oC spowodowało spadek grubości warstwy o 20% w przypadku 24 h nawęglania. Wyznaczono zmiany grubości warstwy nawęglanej w endogazie i twardości na powierzchni od czasu nawęglania.

EN

The study investigated the effectiveness of X5CrNi18-10 stainless steel activation by means of a thin iron coating for low temperature carburizing and the usefulness of the generator endothermic atmosphere for this process. In order to activate the steel surface an iron coating with a thickness of 1–2 µm was applied on it electrolytically electroless. Carburizing was carried out at the temperatures of 450–500oC in the atmospheres based on the generator endothermic atmosphere with the addition of nitrogen or hydrogen. Coating modification by adding a few per cent of sulphur to iron resulted in a reduction of the dispersion of hardness on the surface, and the appearing soot showed a loose connection with the coating. Alternative activation by means of the short-term oxy-nitriding and the following diffusion annealing promoted an increase of hardness on the surface and a reduction of its dispersion after carburizing. After carburizing in endogas of X5CrNi18-10 steel at 470oC during 30 h, a carburized layer with a thickness of approx. 35 μm and the surface hardness of approx. 1150 HV0,05 were obtained. Lowering the carburizing temperature by 20oC resulted in a decrease of the layer thickness by 20% after 24 hours of carburizing. The changes in the thickness of the layer carburized in endogas and the hardness on the surface since the carburization were determined.

14

Prediction of Ferrite Content in Austenitic Cr-Ni Steel Castings During Production

Senberger J., Pernica V., Kana V., Zadera A.

Archives of Foundry Engineering

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2018

|

Vol. 18, iss. 3

91--94

EN

Determination of the ferrite content in austenitic steels, which solidified under defined conditions. Ferrite content in austenitic matrix was determined from samples with wall thickness of 60 mm. Measured ferrite contents served to propose the regression equations for the calculation of the ferrite content in steels with Cr content of 18 up to 22 % and Ni of 9 up to 11 %. An additional regression equation was proposed for steels with a higher Ni content. The proposed regression equations have been checked up on the operating melts. In conclusion, the ferrite content in the axis of the casting of wall thickness of 500 mm has been calculated and it was compared to the ferrite determined in the usual way from the cast-on test.

15

Ausferritic Microstructure Phase Analysis in Ductile Iron

Trzaskowski W., Nawrocki P., Łukasik K., Myszka D.

Archives of Foundry Engineering

|

2018

|

Vol. 18, iss. 2

112--116

EN

Image analysis allows to acquire a number of valuable quantitative informations on the observed structure and make appropriate conclusions. So far, a large part of analyzed images came only from light microscopes, where it was a possibility of accurately distinguish the different phases on the plane. However, the problem happened in the case of the observation of images obtained by scanning electron microscopy. In this case, the presence of various shades of gray, and the spaciousness of the image attained. To perform the analysis the matrix images of the ausferritic ductile iron were used. Full analysis was carried out using the computer program MicroMeter 1.03. Results obtained in the analysis were related directly to the results from X-ray diffraction. Obtained as a result of the analysis were related directly to the results from X-ray diffractometer. The following technique has weaknesses, including the misinterpretation by the operator microscope or program. After all, it was possible to obtain similar results to the result that has been obtained from X-ray diffractometer.

16

The influence of austenitization temperature on phase transformations of supercooled austenite in low-alloy steels with high resistance to abrasion wear

Białobrzeska B., Dziurka R., Żak A., Bała P.

Archives of Civil and Mechanical Engineering

|

2018

|

Vol. 18, no. 2

413--429

EN

The paper presents continuous cooling transformation (CCT) diagram of selected low-alloy steel with high resistance to abrasion. Samples were prepared from examined material in as delivered conditions, then were austenitized at 900, 1000, 1100 and 1200 °C for 20 min, and then cooled with the rates of V800–500 = 50, 10, 5, 1, 0.5, 0.1 °C/s. During the dilatometric research, the critical temperatures were defined as well as the critical points specified for different cooling rates were designated. In addition, metallographic documentation of received microstructures after dilatometric investigations was prepared and hardness measurement was performed. The increase in the austenitizing temperature caused changes in the temperature of MS and in the size of the martensite laths. What is more, the increase in the austenitizing temperature in the case of the analyzed steel caused a displacement of the bainitic and diffusion transformations to longer times. During the analysis using the TEM and SEM it was found that the size of the austenite grains is largely controlled by precipitates of the nitrides of AlN, TiN and carbides, mainly Cr7C3 and M23C6.

17

Effect of plastic deformation on the magnetic properties of selected austenitic stainless steels

Orsulova T., Palcek P., Kudelcik J.

Production Engineering Archives

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2017

|

Vol. 14

15--18

EN

Austenitic stainless steels are materials, that are widely used in various fields of industry, architecture and biomedicine. Their specific composition of alloying elements has got influence on their deformation behavior. The main goal of this study was evaluation of magnetic properties of selected steels, caused by plastic deformation. The samples were heat treated in different intervals of temperature before measuring. Then the magnetic properties were measured on device designed for measuring of magnetism. From tested specimens, only AISI 304 confirmed effect of plastic deformation on the magnetic properties. Magnetic properties changed with increasing temperature.

18

Oprogramowanie do projektowania aktuatorów liniowych wykonanych ze stopów z pamięcią kształtu

Stachowiak D., Kurzawa M., Charchuta I.

Poznan University of Technology Academic Journals. Electrical Engineering

|

2017

|

No. 91

355--364

PL

W artykule przedstawiono algorytm doboru wymiarów aktuatorów wykonanych ze stopów z pamięcią kształtu (SMA) aktywowanych cieplnie. Rozpatrzono dwa rodzaje aktuatorów: cięgnowe oraz sprężynowe. Opracowano również oprogramowanie wspomagające projektowanie aktuatorów liniowych wykonanych ze SMA. Bazując na opracowanym algorytmie oraz programie obliczeniowym zaprojektowano i zbudowano aktuatory cięgnowe wykonane z Flexinolu oraz sprężynowe wykonane z Nitinolu. Podano przykłady zastosowania zaprojektowanych aktuatorów.

EN

The paper presents the design strategy for shape memory alloy linear actuators thermally activated. The attention was focused on SMA wire actuator and SMA spring actuator. The in–house software for designing calculation of SMA actuators has been elaborated. On the basis on described algorithm and using in–house software the SMA wire actuator and SMA spring actuator have been designed and manufactured. The concept proposals of the linear actuator using as active element the Flexinol wire and actuator using Nitinol spring have been given.

19

Influence of Soaking Parameters on the Segregation and Corrosion Resistance of GJS-X350NiMnCu7-3-2 Ductile Iron

Medyński D., Janus A., Stachowicz M.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 2

69--74

EN

In this paper, the effect of changes the parameters of heat treatment on the structure and the degree of elements segregation was determined, in the context of corrosion resistance of ductile iron Ni-Mn-Cu, containing 7.2% Ni, 2.6% Mn and 2.4% Cu. In the condition after casting, castings of austenitic matrix and 160HBW hardness were obtained. The achieved castings were soaked at 450, 550 and 650°C for 4, 8 and 12 hours, then cooled down at the ambient air. In most cases, the heat treatment resulted in a change in the castings matrix, had the consequence of increasing their hardness in comparison to raw castings. Increasing the temperature and prolonging soaking time resulted in increasing the degree of transformation of austenite, while reducing the degree of elements segregation. This led to the formation of slightly bigger number of pitting due to corrosion, but not so deep and more evenly distributed in comparison to raw castings. Wherein the results of corrosion tests show that heat treatment of castings did not significantly change their corrosion resistance in comparison to raw castings, in contrast to the significant increase in mechanical properties.

20

Influence of hot-reduction parameters on the steel austenite structure of a railway wheel

Vakulenko I., Bolotova D., Perkov O., Lisniak A.

Zeszyty Naukowe. Transport / Politechnika Śląska

|

2016

|

z. 93

141--148

EN

The formation of grain structures with boundaries similar to substructures is one of the factors contributing to grain refinement in hot-reduction carbon steel. At the forming of a rim, the slight cooling-down (100-150°С) of the surface volumes is sufficient to increase their strength characteristics. After that, an increase in the magnitude of the hot-hardening of metal in the central rim volumes will lead to the formation of a more uniform fine-grain austenite structure over the rim section.