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1

Evaluation of capabilities of the nanoindentation test in the determination of flow stress characteristics of the matrix material in porous sinters

Madej Lukasz, Legwand Adam, Setty Mohan, Mojzeszko Mateusz, Perzyński Konrad, Roskosz Stanisław, Chrapoński Jacek

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e21, 2022

EN

Herein, we evaluate the nanoindentation test capabilities in the determination of flow stress characteristics of the matrix material in porous sinters. The Distaloy AB sample with 15% porosity after the sintering operation is selected as a case study for the investigation. 2D and 3D imaging techniques are employed first to highlight difficulties in identifying reliable nano hardness measurement zones for further properties evaluation. Then, nanoindentation test results are acquired with Berkovich tip pressed under various loads at different locations in the sample. Systematic indentations in the quartz sample are used as a cleaning procedure to minimize the effect of the possible build-up around the indenter tip. The representative indentation load range is selected based on the extracted material characteristics. With that, the stress–strain response of the sinter matrix material is identified. The reliability of the determined flow stress curve is confirmed with the use of conical nanoindentation measurement results and finite element simulations. Obtained results show that it is possible to calculate reliable flow stress characteristics of the matrix in the porous samples, with the assumption that experiments under various loading conditions and from various locations in the matrix are performed. It is also pointed out that various indentation loads should be used to eliminate the influence of the pile-up or scale effects that affect the overall material response.

2

The Influence of Natural Aging of the AlCu4Mg1 Aluminum Sheet Alloy on the Constitutive Parameters of Selected Models of Flow Stress

Kut Stanisław, Pasowicz Grzegorz, Stachowicz Feliks

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no 5

216--229

EN

This paper presents the results of experimental studies aimed at determining constitutive parameters for selected constitutive equations of flow stress as a function of the natural aging time of 2 mm thick AlCu4Mg1 (AW-2024) sheet. The knowledge of these constitutive parameters as a function of aging time is necessary to analyze and model the processes of forming sheet metal stampings after heat treatment during natural aging. The constitutive parameters in individual constitutive equations were determined on the basis of the approximation of the course of strain hardening curves. The courses of these curves for the tested natural aging times in the range of 0-120 minutes after heat treatment were made on the basis of uniaxial stretching tests of samples taken in the directions of 0, 45 and 90 degrees to the direction of sheet rolling. The values of constitutive parameters as a function of natural aging time were determined for four popular models of flow stress: Hollomon, Swift, Voce and El-Magd. Moreover, the relationship between the natural aging time and the value of the yield strength in the tested aging time range was determined, and the accuracy of the investigated constitutive equations for describing the course of the flow stress of the tested sheet material was assessed on the basis of the analysis of approximation errors.

3

Experiments and analysis of the limit stresses of a magnetorheological fluid

Horak Wojciech, Stępień Barbara, Sapiński Bogdan

Acta Mechanica et Automatica

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2022

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Vol. 16, no. 4

408--416

EN

This paper presents the results of a rheological test of a commercial magnetorheological (MR) fluid (MRF-132DG). The research includes the problem of measuring and interpreting limit stresses under conditions close to the magnetic saturation of the fluid. Four different limit stresses were determined, two related to the yield point and two related to the flow point. Methods for determining limit stresses, especially due to excitation conditions, were also analysed. The aim of this study is to determine the effect of selected parameters on the values of limit stresses of the selected MR fluid. An additional objective is to highlight the problems of defining and interpreting individual limit stresses in MR fluids, particularly in the context of selecting the values of these stresses for the purpose of modeling systems with MR fluids.

4

A repeatability study of artificial neural network predictions in flow stress model development for a magnesium alloy

Siewior Hubert, Madej Łukasz

Computer Methods in Materials Science

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2021

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Vol. 21, No. 4

209--218

EN

This work is devoted to an evaluation of the capabilities of artificial neural networks (ANN) in terms of developing a flow stress model for magnesium ZE20. The learning procedure is based on experimental flow-stress data following inverse analysis. Two types of artificial neural networks are investigated: a simple feedforward version and a recursive one. Issues related to the quality of input data and the size of the training dataset are presented and discussed. The work confirms the general ability of feedforward neural networks in flow stress data predictions. It also highlights that slightly better quality predictions are obtained using recursive neural networks.

5

Study on constitutive behavior of Ti-45Nb alloy under transversal ultrasonic vibration-assisted compression

Wang Xingxing, Qi Zhenchao, Chen Wenliang

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 1

518--532

EN

Ultrasonic vibration technology has been widely applied in plastic forming processes due to its advantages of material properties improvement. In this study, a transverse ultrasonic vibration-assisted compression (TUVC) system with the range of vibration amplitude from 16 to 48 µm is developed to compress the difficult-to-deformation materials. The experiment found that the temperature of the compressed sample with the vibration amplitude of 38 µm arrived at 164 ℃, hence the current constitutive models are deficient for the description of TUVC deformation behavior with the large vibration amplitudes. The results show that the flow stress declines under the coupling action of volume effect and surface effect, especially the amplitude is larger than 38 µm. To accurately depict the constitutive behavior of titanium alloy under TUVC, a hybrid constitutive model considering the difference of softening mechanism was proposed based on crystal plasticity theory, and the predicted curves are in good agreement with experimental results. Finally, the microstructure further revealed the differences of softening mechanism in TUVC, and numerous secondary α phase was precipitated. Consequently, the studies provide an insight into the deformation mechanism of TUVC and promote the application of ultrasonic vibration-assisted forming for the difficult-to-deformation alloy.

6

Prediction of High Strain Rate Flow Behavior of 7175 Aluminum Alloy Based on Arrhenius-Type Constitutive Equations

Shin Young-Chul, Joung Dae-Kwan, Ha Seong-Ho, Choi Ho-Joon, Hyun Soong-Keun

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 4

1361--1364

EN

The flow behavior of 7175 aluminum alloy was modeled with Arrhenius-type constitutive equations using flow stress curves during a hot compression test. Compression tests were conducted at three different temperatures (250°C, 350°C, and 450°C) and four different strain rates (0.005, 0.05, 0.5, and 5 s-1). A good consistency between measured and set values in the experimental parameters was shown at strain rates of 0.005, 0.05, and 0.5 s-1, while the measured data at 5 s-1 showed the temperature rise of the specimen, which was attributable to deformation heat generated by the high strain rate, and a fluctuation in the measured strain rates. To minimize errors in the fundamental data and to overcome the limitations of compression tests at high strain rates, constitutive equations were derived using flow curves at 0.005, 0.05, and 0.5 s-1 only. The results indicated that the flow stresses predicted according to the derived constitutive equations were in good agreement with the experimental results not only at strain rates of 0.005, 0.05, and 0.5 s-1 but also at 5 s-1. The prediction of the flow behavior at 5 s-1 was correctly carried out by inputting the constant strain rate and temperature into the constitutive equation.

7

Material characterization for numerical simulation of manufacturing of automotive part made of magnesium alloy

Pietrzyk Maciej, Kuziak Roman, Bzowski Krzysztof, Rauch Łukasz, Ambroziński Mateusz, Gronostajski Zbigniew, Chorzępa Władysław

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 1

72--81

EN

Evaluation of the possibility of substitution of steel part in the car body by the one made of AZ31 alloy was the main objective of the whole project. The objective of this paper was to determine the flow stress model, which accounts for the difference in the behavior of magnesium alloys during tension and compression. Tension tests on Zwick machine and compression tests on Gleeble 3800 were performed. Inverse analysis was applied to interpretation of the results of the tests. Separate numerical models for tension and compression were implemented into Abaqus software and simulations of the stamping were performed. Sensitivity of the results to the flow stress model was evaluated.

8

The Study of the Effect of Alternate Intermittent Deformation on the Bauschinger Effect in a Zirconium-Based Alloy

Dyja H., Kawałek A., Ozhmegov K., Laber K.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 2

797--803

EN

The article reports the results of research on the influence of the alternate intermittent deformation of specimens by a torsion method on the Bauschinger effect in the Zr-1%Nb zirconium-based alloy. Tests were carried out using an STD 812 torsion plasto-meter. Based on the tests carried out, diagrams have been plotted, which represent the influence of the pre-deformation magnitude, the temperature of heat treatment prior to deformation, and deformation rate on the variation in the values of the flow stress and yield strength of the alloy under study. Conditions have been defined, in which larger magnitudes of plastic deformation of Zr-1Nb% alloy material can be used during its cold plastic working.

9

Effects of V-Ti on Dynamic Recrystallization Behavior and Hot Deformation Activation Energy of 30MSV6 Micro-alloyed Steel

Tavaei K., Meysami A.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 3

1195--1200

EN

In the current study, the hot deformation of medium carbon V-Ti micro-alloyed steel was surveyed in the temperature range of 950 to 1150°C and strain rate range of 0.001 to 1 s-1 after preheating up to 1200°C with a compression test. In all cases of hot deformation, dynamic recrystallization took place. The influence of strain rate and deformation temperature on flow stress was analyzed. An increase in the strain rate and decrease in the deformation temperature postponed the dynamic recrystallization and increased the flow stress. The material constants of micro-alloyed steel were calculated based on the constitutive equations and Zener-Hollomon parameters. The activation energy of hot deformation was determined to be 458.75 kJ/mol, which is higher than austenite lattice self-diffusion activation energy. To study the influence of precipitation on dynamic recrystallization, the stress relaxation test was carried out in a temperature range of 950 to 1150°C after preheating up to 1200°C. The results showed no a stress drop while representing the interaction of particles with dynamic recrystallization.

10

Zmiany właściwości reologicznych wybranych stopów AlMg w próbie ściskania

Sawicki S., Dyja H., Kawałek A., Laber K., Wiśniewska-Weinert H.

Obróbka Plastyczna Metali

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2017

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T. 28, nr 1

59--74

PL

W pracy zaprezentowano metodę wyznaczania krzywych umocnienia stopów AlMg: 5754, 5083, 5019 oraz 5XXX w oparciu o próbę ściskania cylindrycznych próbek o średnicy 10 mm i wysokości 12 mm. Badania przeprowadzono za pomocą fizycznego symulatora procesów metalurgicznych GLEEBLE 3800 w Instytucie Przeróbki Plastycznej i Inżynierii Bezpieczeństwa Politechniki Częstochowskiej. Urządzenie to umożliwia przeprowadzenie badań przy temperaturach odpowiadających rzeczywistym warunkom przeróbki plastycznej. Określono podatność badanych stopów do kształtowania plastycznego w zakresie temperatur 360–560°C oraz prędkości odkształceń z przedziału 0,05–1,0 s-1. Naprężenie uplastyczniające σp, czyli naprężenie niezbędne do zainicjowania i kontynuacji plastycznego płynięcia metalu, w warunkach jednoosiowego stanu naprężenia jest funkcją odkształcenia (ε), prędkości odkształcenia (ε& ), temperatury (T) i historii przebiegu odkształcenia. Wyznaczenie charakterystyk technologicznej plastyczności jest szczególnie trudne dla warunków przeróbki plastycznej na gorąco, gdyż w strukturze materiału zachodzą jednocześnie procesy wynikające z mechanizmu odkształcenia plastycznego oraz procesy umocnienia, jak i aktywowane cieplnie, zależne od czasu, zjawiska prowadzące do osłabienia materiału. Określenie wartości σp badanych stopów AlMg ma duże znaczenie podczas projektowania procesów przeróbki plastycznej na gorąco. W oparciu o rejestrowane w czasie eksperymentu parametry odkształcenia plastycznego możliwe było poddanie danych obróbce matematycznej, filtracji cyfrowej oraz aproksymacji. Następnie za pomocą metody odwrotnej określono rzeczywiste wartości współczynników występujących w modelach numerycznych do własności reologicznych badanych materiałów.

EN

This paper presents a method for determining hardening curves of AlMg alloys: 5754, 5083, 5019 and 5XXX based on a compression test of cylindrical specimens with a diameter of 10 mm and height of 12 mm. Tests were conducted by means of the GLEEBLE 3800 physical simulator of metallurgical processes at the Institute of Metalworking and Safety Engineering of Częstochowa University of Technology. This machine makes it possible to conduct tests at temperatures corresponding to actual metalworking conditions. The formability of the studied alloys was determined within the temperature range of 360–560°C and for strain rates within the range of 0.05–1.0 s-1. Flow stress σp, or the stress required to initiate and continue plastic flow of metal in a uniaxial stress state, is a function of strain (ε), strain rate (ε&), temperature (T) and the history of strain. Determination of technological plasticity curves is particularly difficult for hot working conditions, since processes resulting from the plastic strain mechanism and hardening processes, as well as thermally activated, time-dependent phenomena leading to weakening of the material occur simultaneously in the material’s structure. Determination of the σp value of tested AlMg alloys is of great significance when designing hot plastic working processes. Based on the plastic strain parameters registered during the experiment, it was possible to mathematically process data, filter it digitally and conduct approximation. Next, actual values of coefficients present in numerical models of the rheological properties of the studied materials were determined by means of the inverse method.

11

Wpływ parametrów odkształcenia na gorąco na mikrostrukturę i właściwości plastyczne stopu magnezu AZ31

Hadasik E., Kuc D., Bednarczyk I.

Hutnik, Wiadomości Hutnicze

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2017

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Vol. 84, nr 8

306--309

PL

W artykule przedstawiono wpływ parametrów odkształcenia na technologiczną plastyczność i mikrostrukturę stopu AZ31. Wykonano próby ciągłego, dwustopniowego oraz wielostopniowego odkształcenia na gorąco w celu analizy wpływu parametrów tj. temperatura nagrzewania, wielkość odkształcenia, prędkość odkształcenia oraz czas wytrzymania po odkształceniu na mikrostrukturę i plastyczność badanego stopu.

EN

The article is presented the effect of deformation parameters on the plasticity and microstructure of alloy AZ31. Continuous, two-stage and multi-stage hot deformation tests were performed to analyze the effect of parameters such as heating temperature, deformation size, deformation speed and deformation time after deformation on the alloy microstructure and plasticity of the alloy.

12

The Influence of Temperature and Strain Rate on Flow Stress of Steel 10CrMo9-10 used for Drawing of Tubes

Kapustova M., Sobota R., Bilik J., Moravcik R.

Hutnik, Wiadomości Hutnicze

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2017

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Vol. 84, nr 8

368--370

EN

The contribution brings an analysis of influence of essential thermomechanical forming conditions of creep resistant steel type 10CrMo9-10 on its flow stress. For experimental purposes the thermomechanical parameters of temperature and strain rate were selected. The mentioned parameters mostly influence the forming process. Cold tensile test was used as well as tensile test at increase temperatures 100°C, 150°C a 200°C at two defined strain rates. Selection of temperatures resulted from process conditions at die drawing of seamless tubes. The experiment result were created flow stress curves which will help achieve reliable numeric simulation of cold die drawing of steel tubes. Research of temperature and strain rate influence on flow stress of creep resistant steel 10CrMo9- 10 is important for increase of precision of required dimensions of final drawn tubes.

PL

Niniejsza praca prezentuje analizę wpływu podstawowych termomechanicznych warunków kształtowania stali odpornej na pełzanie typu 10CrMo9-10 na jej naprężenie uplastyczniające. Dla celów eksperymentalnych wybrano spośród parametrów termomechanicznych temperaturę oraz szybkość odkształcania. Wspomniane parametry najbardziej wpływają na proces kształtowania. Przeprowadzono próbę rozciągania na zimno raz próby rozciągania w temperaturze podwyższonej 100°C, 150°C i 200°C dla dwóch określonych szybkościach odkształcania. Wybór temperatur podyktowany był warunkami procesu ciągnienia w ciągadle dla rur bez szwu. Wyniki testu to krzywe granicy plastyczności które pomogły w przygotowaniu wiarygodnych symulacji numerycznych dla ciągnienia na zimno rur stalowych. Badania wpływu temperatury i szybkości odkształcania odpornej na pełzanie stali typu 10CrMo9- 10 na jej naprężenie uplastyczniające są ważne dla uzyskania lepszej precyzji i wymaganych wymiarów końcowego produktu w postaci rur ciągnionych.

13

Finite Element Modelling of Titanium Aluminides

Sizova I., Sviridov A., Günther M., Bambach M.

Computer Methods in Materials Science

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2017

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Vol. 17, No. 1

51--58

EN

Hot forging is an important process for shaping and property control of lightweight titanium aluminide parts. Dynamic recrystallization and phase transformations play an essential role for the resulting grain size and accordingly the mechanical properties. Due to the fact that titanium aluminides require forging under isothermal conditions, reliable process modeling is needed to predict the microstructure evolution, to optimize the process time and to avoid excessive die loads. In the present study an isothermal forging process of a compressor blade made of TNB-V4 (Ti–44.5Al–6.25Nb–0.8Mo–0.1B, at. %) is modeled using the Finite Element (FE) – Software Q-Form. A microstructure model describing the microstructure evolution during forging is presented. To calibrate the model, the high-temperature deformation behavior was investigated using isothermal compression tests. The tests were carried out at temperatures from 1150°C to 1300°C, applying strain rates ranging from 0.001s-1 to 0.5s-1, up to a true strain of 0.9. The experimentally determined flow stress data were described with model equations determined form the course of the strain hardening rate in Kocks-Mecking plots. An isothermal forging process of a compressor blade was carried out and used to validate the results from the FE simulations.

PL

Plastyczna przeróbka na gorąco jest ważnym procesem po-zwalającym nadawać kształt i kontrolować własności wyrobów z glinków tytanu. Dynamiczna rekrystalizacja i przemiany fazowe odgrywają kluczową rolę w kształtowaniu końcowej wielkości ziarna i, w konsekwencji, własności mechanicznych wyrobu. Ponieważ glinki tytanu wymagają kucia w warunkach izotermicznych, potrzebny jest dokładny model rozwoju mikrostruktury aby umożliwić optymalizację czasu trwania procesu i aby uniknąć przeciążenia matryc. W niniejszej pracy proces kucia łopatki kompresora został zamodelowany metodą elementów skończonych (MES) z wykorzystaniem programu Q-Form. Badanym materiałem był stop TNB-V4 (Ti—44.5Al-6.25Nb-0.8Mo-0.IB, at. %). W pracy przedstawiono zastosowany model rozwoju mikrostruktury. Model został skalibrowany na podstawie wyników prób ściskania na gorąco w warunkach izotermicznych. Badania przeprowadzono w temperaturach w zakresie 1150°C - 1300°C i dla prędkości odkształcenia w zakresie 0.001 s"1 d 0.5 s' . Całkowite odkształcenie w tych próbach wynosiło 0.9. Wyznaczone doświadczalnie naprężenie uplastyczniające zostało opisane za pomocą prędkości umocnienia zgodnie z krzywymi Kocksa-Meckinga. Fizyczny proces kucia łopatki kompresora został wykorzystany do walidacji modelu MES.

14

Analytical Descriptions of Dynamic Softening Mechanisms for Ti-13Nb-13Zr Biomedical Alloy in Single Phase and Two Phase Regions

Quan G.-Z., Wang X., Li Y.-L., Zhang L.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 4

2029--2043

EN

Dynamic softening behaviors of a promising biomedical Ti-13Nb-13Zr alloy under hot deformation conditions across dual phase α + β and single phase β regions were quantitatively characterized by establishing corresponding dynamic recovery (DRV) and dynamic recrystallization (DRX) kinetic models. A series of wide range hot compression tests on a Gleeble-3500 thermo-mechanical physical simulator were implemented under the strain rate range of 0.01-10 s−1 and the temperature range of 923-1173 K. The apparent differences of flow stress curves obtained in dual phase α + β and single phase β regions were analyzed in term of different dependence of flow stress to temperature and strain rate and different microstructural evolutions. Two typical softening mechanisms about DRV and DRX were identified through the variations of a series of stress-strain curves acquired from these compression tests. DRX is the dominant softening mechanism in dual phase α + β range, while DRV is the main softening mechanism in single phase β range. The DRV kinetic model for single phase β region and the DRX kinetic model for dual phase α + β region were established respectively. In addition, the microstructures of the compressed specimens were observed validating the softening mechanisms accordingly.

15

Charakterystyki plastyczności miedzi w warunkach złożonych i cyklicznie zmiennych obciążeń

Pawlicki J.

Rudy i Metale Nieżelazne Recykling

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2015

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R. 60, nr 11

550--554

PL

W artykule przedstawiono charakterystykę stanowiska badawczego i oprzyrządowania do realizacji odkształcenia w warunkach złożonego stanu obciążenia. Próby odkształcania przeprowadzono według odpowiednio dobranych wariantów odkształcenia, przy założeniu określonej wielkości odkształcenia pojedynczego i odkształcenia całkowitego. Proste próby odkształcania: rozciąganie, ściskanie i skręcanie realizowano w celu uzyskania danych stanowiących podstawę do określenia efektów w próbach złożonego odkształcania. Najkorzystniejsze efekty uzyskano dla odkształcania w procesie rewersyjnego skręcania i w procesie złożonym, łączącym rozciąganie lub ściskanie z równoczesnym rewersyjnym skręcaniem. Korzystne efekty tych procesów obejmują zmniejszenie wielkości maksymalnych naprężeń uplastyczniających oraz zwiększenie wielkości odkształceń granicznych.

EN

Features of the test stand and equipment for conducting deformation under complex load conditions have been presented in the paper. Tests were performed in selected deformation variants with the assumed individual and total strain values. Simple deformation tests, such as tension, compression and torsion, were conducted in order to achieve data that would be a base for estimation of the effects of complex deformation tests. The most favourable effects have been achieved when deformation were realized by reversible torsion or by complex loading that combines simultaneous tension or compression with reversible torsion. Advantages of such deformation techniques include decreasing the maximum flow stress values and increasing the limit deformation values.

16

Zmiana naprężenia uplastyczniającego za pomocą superkondensatorów

Zimniak Z.

Przegląd Mechaniczny

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2015

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nr 11

28--31

PL

Zostało wykazane, że pod wpływem przepływającego pulsacyjnego prądu o dużej gęstości zmniejsza się w metalach naprężenie uplastyczniające. Efekt działania pulsacyjnego prądu na naprężenie uplastyczniające nazwano efektem elektroplastycznym. W niniejszej pracy przedstawiono wyniki otrzymane z próby jednoosiowego rozciągania próbek z zastosowaniem jednoczesnego przepływu impulsowego prądu elektrycznego. W tym celu został zaprojektowany i wykonany generator prądu pulsacyjnego, w którym zastosowano superkondensatory Badania eksperymentalne zostały przeprowadzone przy niskim napięciu zasilania (2,5 V) z zastosowaniem różnych parametrów prądu, w tym czasu jego przepływu i częstotliwości. W badaniach doświadczalnych w celu pokazania skutków działania efektu elektro-pulsacyjnego użyto dwóch materiałów - stali nierdzewnej 0H18N9 oraz stopu magnezu AZ31. Wynikiem badań jest opracowanie techniki niskonapięciowego elektroplastycznego odkształcania metali, która przyczyni się do dalszego rozwoju zaawansowanych procesów obróbki plastycznej metali.

EN

It has been found that a high-density current pulse can reduce the flow stress of metals. The effect of electric current pulses on the plastic flow of materials is generally known as the electroplastic effect. In this paper, a pulsed electric current is applied to a specimen simultaneously with a quasi-static uniaxial tensile load. To do so a short-time current pulse generator, inducing supercapacitors was designed and manufactured. The experiments with low operating voltage (2.5 V) were performed at different electric current pulse period and frequency The electroplasticity of stainless steel 0H18N9 and AZ31 magnesium alloy under a pulsed electric current is investigated experimentally The result of the present study with low operating voltage is expected to provide a basis to develop advanced metal forming processes using electroplasticity.

17

Laboratory melting, casting and forging of manganese TWIP steel

Martinek P., Podany P., Duchek M., Konopik P.

Journal of Achievements in Materials and Manufacturing Engineering

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2015

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Vol. 71, nr 1

39--44

EN

Purpose: The article deals with the possibility of experimental melting, casting and forging of these kinds of steel in laboratory induction melting furnace Design/methodology/approach: The metallographic tests and Rastegaev compression test were made to describe microstructural properties and flow stress behaviour at different forging temperatures. Findings: Results of this test show the true stress - true plastic strain diagrams which can be used as a data input to the numerical simulation of forging for example in DEFORM 3D simulation software. Research limitations/implications: Microstructure analysis proved successful handling during all forging operations - no cracks and similar defects were observed in the microstructure. Practical implications: Transportation industry demands high strength steels with the possibility to absorb high energy in case of a sudden collision. In recent years, so-called TWIP steels are in the focus of research of materials with high strength suitable for car bodies. Originality/value: TFeMn TWIP is a high-strength steel concept with superior formability, which may be close to being produced industrially. High manganese TWIP steels are highly ductile, high strength Mn austenitic steels characterized by a high rate of work hardening resulting from the generation of deformation-nucleated twins.

18

Naprężenie uplastyczniające i mikrostruktura stali wysokomanganowej z aluminium

Kuc D., Pidvysotsk'yy V., Lalik S., Perzyński G.

Hutnik, Wiadomości Hutnicze

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2015

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Vol. 82, nr 8

482--487

PL

Celem pracy jest opracowanie modelu reologicznego stali wysokomanganowej z aluminium odkształcanej na gorąco. Wykonano badania plastometryczne stali X60MnAl30-9 w temperaturze od 900 do 1150°C z prędkością odkształcenia 0,1÷10 s-1. Przeprowadzono identyfikację parametrów modelu Tegart-Sellars opartego na funkcji zmiennych zewnętrznych, metodą analizy odwrotnej. Opracowany model umożliwił obliczenia parametrów siłowych, w warunkach wielostopniowego odkształcania. Określono mikrostrukturę badanej stali w warunkach ciągłego i wieloetapowego odkształcania.

EN

The aim of the paper is to prepare a rheological model of hot-formed high manganese steel with aluminium. Plastometric tests of steel X60MnAl30-9 were conducted in temperature from 900 to 1150°C with deformation speed of 0.1÷10 s-1. Parameters identification was conducted of Tegart-Sellars model, based on function of external variables with the use of reverse analysis method. Prepared model enabled calculations of force parameters in conditions of multistage deformation. The microstructure of tested steel was also determined in conditions of multistage deformation.

19

Badania plastometryczne metodą skręcania stali przeznaczonych do walcowania walcówki

Hadasik E., Płachta A., Tkocz M., Niewielski G., Ducki K.

Hutnik, Wiadomości Hutnicze

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2015

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Vol. 82, nr 9

579--583

PL

W pracy przedstawiono wyniki badań plastyczności stali 30MnB4 i C45 przeznaczonych do walcowania walcówki w nowoczesnej walcowni ciagłej. Oceny plastyczności dokonano w próbie skręcania na gorąco, w zakresie temperatury walcowania walcówki od 850 do 1150oC i z prędkością odkształcenia 0,1, 1 i 10 s-1. Podstawę do oceny plastyczności stanowiły zależności naprężenia uplastyczniajacego od odkształcenia, otrzymane na podstawie rejestrowanego momentu skrecającego w funkcji liczby skręceń próbki. Na ich podstawie określono charakterystyczne wielkości, takie jak: maksymalne naprężenie uplastyczniające, wartość odkształcenia odpowiadającą maksymalnemu naprężeniu oraz odkształcenie do zniszczenia. Wielkości te uzależniono od parametrów odkształcenia oraz opracowano zależności pomiędzy maksymalnym naprężeniem uplastyczniającym, odpowiadającym mu odkształceniem a energią aktywacji procesu odkształcania i parametrem Zenera-Hollomona.

EN

The paper presents results of steel 30MnB4 and C45 plasticity tests meant for rolling wire rods on modern continuous rolling mill. Plasticity assessment was conducted in hot torsion test performed on swing plastometer in temperature range of rolling wire rode from 850 to 1150°C and deformation speed of 0.1; 1 and 10 s-1. The basis for plasticity assessment was the dependency between flow stress and deformation achieved on the basis of registered torsion moment in function of the number of sample torsions. On such basis the characteristic values were determined: peak flow stress, deformation value which corresponds with peak stress and deformation to failure. Those values are dependent on deformation parameters and certain dependencies between peak flow stress and corresponding deformation with activation energy of the deformation process and Zener-Hollomon parameter were elaborated.

20

Badania plastometryczne własności reologicznych stopu aluminium 6082 w warunkach procesu wyciskania

Andrzejewski D., Dyja H., Sawicki S.

Rudy i Metale Nieżelazne Recykling

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2014

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R. 59, nr 8

395--398

PL

W artykule podjęto badania plastyczności stopu aluminium 6082 przeznaczonego do wyciskania. Badania przeprowadzono za pomocą symulatora cieplno-mechanicznego Gleeble 3800 w temperaturze 440-560 °C oraz przy prędkości odkształcenia 0,5-5 s–1, w warunkach odpowiadających procesowi wyciskania. Przedstawiono krzywe płynięcia metalu, które posłużą do symulacji komputerowej.

EN

In the work have been taken research of plasticity 6082 aluminum alloy intended for extrusion. The tests were performed using a thermo-mechanical simulator Gleeble 3800 at 440-560 °C, and at a strain rate of 0.5-5 s–1. These are the conditions corresponding to the extrusion process. The curves of metal flow that will be used for computer simulation, have been shown.