Wyniki wyszukiwania - BazTech

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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

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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.

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Modeling with FCA-Based Model of Microstructure Evolution of MgCa08 Alloy During Drawing of Thin Wire in Heated Die

Svyetlichnyy D. S., Kustra P., Milenin A.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 4

2721--2728

EN

The paper deals with a modeling of manufacturing process of thin wire of MgCa08 alloy used as biocompatible soluble threads for medical application. Some difficulties in material deformation subjected with its hexagonal structure can be solved with accurate establishment of the deformation conditions, especially temperature history of the whole process. In drawing process with heated die, wire is preheated in furnace and then deformed. The only narrow temperature range allows for multi-pass drawing without wire breaking. Diameter below 0.1 mm required for the final product makes very important the consideration of microstructure evolution because grain size is comparable with the wire dimensions. For this reason the problem is considered in the micro scale by using the frontal cellular automata (FCA)-based model. The goals of present work are the development and validation of FCA-base model of microstructure evolution of MgCa0.8 magnesium alloy. To reach this objective, plastometric and relaxation tests of MgCA08 alloy were done on physical simulator GLEEBLE 3800. Results of the experimental studies were used for parameters identification of the hardening-softening model of the material. Then, initial microstructure and its evolution during the drawing passes were simulated with FCA-based model. FCA consider dislocation density and flow stress, hardening and softening including recovery and recrystallization, grain refinement and grain rotation, as well as grain growth. It allows one to obtain structures close to real ones. Two variants of the drawing process with different temperature history were considered. The deformation scheme was the same. Simulation results with following short discussion confirm usefulness of FCA-based model for explanation and selection of rational technological condition of thin wire drawing of MgCa08 alloy.

PL

W pracy rozpatrzono proces wytwarzania cienkich drutów z biozgodnego stopu MgCa0.8 z przeznaczeniem na resorbowalne nici chirurgiczne. W procesie ciągnienia drut nagrzewany jest w piecu a następnie odkształcany. Jednym z warunków, jaki musi być spełniony w technologicznym procesie jest zachodzenie rekrystalizacji w trakcie ciągnienia. Pozwala to na realizację wielo przepustowego procesu ciągnienia bez wyżarzania międzyoperacyjnego. Prognozowanie rekrystalizacji na etapie projektowania technologii wymaga stworzenia modelu rekrystalizacji. W przypadku ciągnienia drutów o średnicach mniejszych niż 0.1 mm konieczne jest zastosowania modelu w skali mikro. Celem pracy jest opracowanie modelu rekrystalizacji, opartego o frontalne automaty komórkowe (FCA) oraz przykładowa symulacja kilku przepustów ciągnienia. Do kalibracji modelu FCA wykorzystano badania plastometryczne oraz testy relaksacji stopu MgCa08 przy użyciu symulatora fizycznego GLEEBLE 3800. Wyniki tych badań pozwoliły wyznaczyć parametry modelu umocnienia-mięknięcia materiału. Następnie początkowa mikrostruktura i jej rozwój podczas procesu ciągnienia były analizowane za pomocą modelu opartego o FCA, który uwzględnia gęstość dyslokacji, naprężenie uplastyczniające, umocnienie i mięknięcie w tym zdrowienie i rekrystalizację, rozdrobnienie ziaren oraz ich rotację i rozrost, co pozwala na uzyskanie struktury bliskiej do rzeczywistej. Dwa warianty procesu ciągnienia o różnej historii zmiany temperatury rozpatrzono w pracy. Wyniki symulacji potwierdziły przydatność modelu opartego o FCA do uzasadnienia i wyboru racjonalnych warunków technologicznych ciągnienia cienkich drutów za stopu MgCa08. W pracy przedstawiono również praktyczną implementację procesu ciągnienia.

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Badania doświadczalne wpływu temperatury walcowania na własności mechaniczne taśm aluminiowych w procesie walcowania pakietowego ARB

Kwapisz M., Svyetlichnyy D. S., Milenin A.

Rudy i Metale Nieżelazne

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2007

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R. 52, nr 5

272-275

PL

W artykule przedstawiono wyniki badań doświadczalnych walcowania pakietowego aluminium, przeprowadzonych na walcarce laboratoryjnej Politechniki Częstochowskiej, oraz wpływu temperatury walcowania na własności mechaniczne aluminium o ultradrobnoziarnistej strukturze. W pracy przedstawiono wyniki badań umownej granicy plastyczności, wytrzymałości na rozciąganie, wydłużenia całkowitego, mikrotwardości oraz siły walcowania.

EN

Recently an interest in materials with ultra-fine structure arouses constantly. Among the several methods of severe deformation that allows for obtaining such a structure accumulative roll-bonding (ARB) process is well placed. The ARB process is a one that can be fitted for mass bulk production. The cycle of Accumulative Roll-Bonding process consists of several stages: cutting of the strip, surfaces cleaning and degreasing, putting into a packet two or more strips, and rolling the packet with reduction, which gives the same sizes of the strip as before the cutting. Repeating of the several cycles is carried out in order to obtain severe deformation, which results on receiving of ultra-fine microstructure of aluminum and unique mechanical properties. In the paper, results of experimental study of the accumulative roll-bending process of aluminum strips are presented. The general difference of the ARB process, which has been carried out on laboratorial stand in Częstochowa University of Technology, is a rolling in bracket grooves. Such a modification make possible to realize more passes and to study properties of aluminum under more severe deformation. For the better bonding during the rolling, the metal before deformation is reheated. The rolling temperature effects on the microstructure development and mechanical properties of aluminum, as well. Results of measurements of the yield strength, ultimate tensile strength, elongation, microhardness and rolling force are shown in the paper. The yield strength, ultimate tensile, microhardness and rolling force arise in the several first passes, and then after short stabilization, their values decrease slightly. Elongations demonstrate reverse dependence: after decided drop and stabilization increasing come on. Basing on obtained results, a model that describes a microstructure evolution and mechanical properties during the accumulative roll-bonding process will be developed.