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1
Content available Application of acoustic emission to the analysis of phase transformations in 27MnCrB5-2 steel tests during continuous cooling
Trafarski Andrzej, Łazarska Małgorzata, Ranachowski Zbigniew
Bulletin of the Polish Academy of Sciences. Technical Sciences
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2021
|
Vol. 69, nr 6
art. no. e139389
EN
The goal of the research was to analyze the acoustic emission signal recorded during heat treatment. On a special stand, samples prepared from 27MnCrB5-2 steel were tested. The steel samples were heated to 950°C and then cooled continuously in the air. Signals from phase changes occurring during cooling were recorded using the system for registering acoustic emission. As a result of the changes, Widmanstätten ferrite and bainite structures were observed under a scanning microscope. The recorded acoustic emission signal was analyzed and assigned to the appropriate phase transformation with the use of artificial neural networks.
2
Content available remote Selection of the best phase transformation model for optimization of manufacturing processes of pearlitic steel rails
Kuziak Roman, Pidvysots'kyy Valeriy, Pernach Monika, Rauch Lukasz, Zygmunt Tomasz, Pietrzyk Maciej
Archives of Civil and Mechanical Engineering
|
2019
|
Vol. 19, no. 2
535--546
EN
Selection of the best model for simulation of manufacturing processes of pearlitic steel rails was the objective of the paper. Achieving a proper balance between its predictive capabilities and computing costs was used as a criterion. Review of the pearlitic transformation models was performed and modification of the JMAK equation was selected for further analysis. Empirical models were developed to describe microstructure and mechanical properties of rails. Dilatometric tests were performed to supply data for identification of the phase transformation model. Physical simulations of various thermal cycles were performed to validate and verify the models. Finite element (FE) simulations of the hot rolling provided distributions of the temperature and the austenite grain size at the cross section of the rail, which were used as an input for modelling of phase transformations during cooling. Accelerated cooling by a cyclic immersion of the rail head in the polymer solution was considered as a case study. Performed simulations confirmed good predictive capabilities of the model.
3
Content available Austenite transformation simulation for a controlled rolling processing technology development
Kaverinsky V.
Archives of Mechanical Technology and Materials
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2018
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Vol. 38
35--39
EN
Using an originally-developed computer model and appropriate software the impact of deformation on austenite phase transformation in low carbon alloyed steel was carried out. The computer simulation takes into account an impact of the deformation degree and takes into account non-constant cooling rate. That makes it useful for the development of thermal and deformation technological processes development. Based on the simulation results a technology of controlled rolling of low carbon steel alloyed by carbide forming elements (Nb, V, Ti) was developed. The proposed technique allows production of rolled steel sheets with high strength and plastic properties, as well as high impact strength in normal and low temperatures.
4
Content available remote Numerical analysis of temperature and residual stresses in hot-rolled steel strip during cooling in coils
Witek S., Milenin A.
Archives of Civil and Mechanical Engineering
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2018
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Vol. 18, no. 2
659--668
EN
The main factors influencing on the level of residual stresses in hot rolled steel strips are related with uneven temperature and microstructure changes during cooling on the run-out table and in a coil. That is why in this work, development of coil cooling model with taking into account the influence of radial stresses on the effective thermal conductivity in the radial direction was performed. In order to assess the influence of the phase transformations in the coil on the level of residual stresses, the different laminar cooling strategies were applied. The results of numerical simulations obtained in this work were validated in industrial conditions. It is shown that the end of phase transformations in the strip coil has a significant influence on the level of residual stresses.
5
Content available Constitutive modelling and identification of parameters of 316L stainless steel at cryogenic temperatures
Ryś M.
Acta Mechanica et Automatica
|
2014
|
Vol. 8, no. 3
136--140
EN
In this work, a macroscopic material model for simulation two distinct dissipative phenomena taking place in FCC metals and alloys at low temperatures: plasticity and phase transformation, is presented. Plastic yielding is the main phenomenon occurring when the yield stress is reached, resulting in nonlinear response of the material during loading. The phase transformation process leads to creation of two-phase continuum, where the parent phase coexists with the inclusions of secondary phase. An identification of the model parameters, based on uniaxial tension test at very low temperature, is also proposed.
6
Content available Żaroodporność i żarowytrzymałość stali typu Fe-Cr-Al w warunkach utleniających; aktualny stan i perspektywy badań
Homa M.
Prace Instytutu Odlewnictwa
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2008
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T. 48, z. 3
57-85
PL
Praca przedstawia krytyczną analizę obecnego stanu wiedzy na temat badań nad żaroodpornością stali typu Fe-Cr-Al z grupy AFA (Alumina Forming Alloys), których zachowanie w środowisku gorących gazów jest od lat przedmiotem wnikliwych badań. W warunkach wysokotemperaturowego utleniania tworzy się na ich powierzchni ochronna warstwa zgorzeliny zbudowana z tlenku glinu, który może występować w różnych odmianach krystalograficznych. Odmiany fazowe mogą ulegać transformacji od niestabilnej fazy γ poprzez δ i θ do stabilnej fazy α. O rodzaju utworzonej fazy decyduje temperatura procesu utleniania, skład atmosfery oraz czas. Przemianom fazowym tlenku glinu towarzyszy zmiana szybkości utleniania stali, ponieważ niestabilne tlenki wykazują wyższe szybkości narastania niż stabilny tlenek α-Al2O3. Dodatkowo w trakcie transformacji fazowej obserwuje się zmiany morfologii powierzchni tworzących się zgorzelin. Fazy przejściowe na ogół występują w postaci płytek, bardzo cienkich długich kryształów (whiskerów) oraz tworów blaszkowych, tworzących silnie rozwinięte powierzchnie, podczas gdy faza α wykazuje budowę kolumnową a utworzona z niej powierzchnia zgorzeliny jest pofałdowana.
EN
This work reviews the current state of research regarding high temperature oxidation resistance of Fe-Cr-Al steels, that belong to a family of AFA (Alumina Forming Alloys). The behavior of these steels in hot gases environment is a subject of intensive research. During high temperature oxidation, the protective layer of alumina oxide is formed on their surface, which can have different crystallographic forms. Moreover, Al2O3 can transform from instable γ- phase to δ, θ and finally stable α-phase. The type of alumina depends on temperature, time and atmosphere composition. The phase transformation of aluminum oxide is accompanied with change of oxidation kinetics because instable oxides grow faster than unstable ones. Additionally, during phase transformation the morphology change of surfaces is observed. Instable phases have the form of platelets, very long thin crystals (whiskers) and blade-like crystals, in all cases resulting in the formation of highly developed scale surface. Stable α-phase shows columnar crystals construction with corresponding pleated scale surface.
7
Content available remote Zachowanie się stopów NiAl w warunkach wysokotemperaturowego utleniania
Łatka D.
Czasopismo Techniczne. Chemia
|
2007
|
R. 104, z. 1-Ch
87-95
PL
W niniejszym artykule przedstawiono dotychczasowy stan wiedzy na temat utleniania stopów NiAl w atmosferze powietrza. Dodatek glinu powoduje, że w trakcie wysokotemperaturowego utleniania na ich powierzchni mogą się tworzyć tlenki glinu [gamma]-, [delta]-, [alfa]-, które ulegają transformacjom fazowym. Spośród wszystkich odmian fazowych jedynie odmiana [alfa]-Al.[2]O[3] posiada najlepsze właściwości ochronne.
EN
In this article the state of art in oxidation alloys of NiAl in air. At high temperature oxidation on their surface can be formed scale [gamma]-, [delta]-, [alfa]- Al[2]O[3]. These phases can be transformed. Phase [alfa]-Al[2]O[3] has excellent hot corrosion resistance.
8
Content available remote Właściwości zgorzeliny Al2O3 tworzącej się na stalach typu Fe-Cr-Al w trakcie wysokotemperaturowego utleniania
Homa M., Żurek Z.
Czasopismo Techniczne. Chemia
|
2005
|
R. 102, z. 7-Ch
11--23
PL
W niniejszej pracy przedstawiono dotychczasowy stan wiedzy na temat zgorzelin tlenkowych Al2O3. Tlenki te mogą tworzyć się na powierzchni stali typu Fe-Cr-Al w trakcie wysokotemperaturowego utleniania w różnych atmosferach.
EN
In this work the state of art in alumina scale was presented. These aluminas can be formed on Fe-Cr-Al steel surface during high temperature oxidation at different atmospheres.
9
Content available remote Two-dimensional condensation of small organic molecules at electrodes
Donner C., Pohlmann L., Kirste S., Baumgärtel H.
Chemia Analityczna
|
2000
|
Vol. 45, No. 2
175-188
EN
The adsorption of organic molecules at electrodes leads to two- dimensional "gas-like" systems at the electrode surface. It is well known that these adsorbates under certain conditions of electrode potential, bulk concentration and temperature undergo a phase transition forming two- dimensional molecular films with well defined structures. Several substance classes undergo such a phase transition or condensation. Among them, the DNA bases are of special interest. The thymine and adenine condensation are reported on as examples of film formation. The main emphasis is put on the kinetics of film formation. The kinetics has been studied by potential jump experiments. Depending on the start and final potentials different shapes of current transients can be detected. On the basis of a qualitative interpretation of these different shapes, a new method for the determination of the potential of maximum adsorption is developed. This method is applied to the systems of thymine and adenine, respectively, adsorbed on mercury electrodes. The knowledge of this potential with respect to the potential of zero charge of the pure electrolyte allows to calculate the orientation and reorientation of the organic dipoles in relation to the electrode surface.
PL
Adsorpcja cząsteczek organicznych na powierzchni elektrod prowadzi do dwuwymiarowych gazopodobnych układów. Zaadsorbowane związki w pewnych warunkach ulegają transformacji fazowej z utworzeniem dobrze zdefiniowanych dwuwymiarowych struktur. Spośród substancji ulegających przemianom fazowym szczególnie interesujące są zasady DNA takie jak tymina i adenina. Głównym aspektem w pracy jest kinetyka tworzenia filmów wymienionych zasad. Analizując kształty przebiegów prądowych przy różnych potencjałach opracowano nową metodę wyznaczania potencjału maksimum adsorpcji tyminy i adeniny na elektrodach rtęciowych. Znajomość odchylenia tego potencjału od potencjału zerowego ładunku w czystym elektrolicie pozwala na obliczenie orientacji i reorientacji organicznych dipoli na powierzchni elektrody.
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