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Study of Hot Deformation Behavior of CuFe2 Alloy

Schindler I., Sauer M., Kawulok P., Rodak K., Hadasik E., Jabłońska M. Barbara, Rusz S., Ševčák V.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 2

701--706

EN

Nil strength temperature of 1062°C and nil ductility temperature of 1040°C were experimentally set for CuFe2 alloy. The highest formability at approx. 1020°C is unusable due to massive grain coarsening. The local minimum of ductility around the temperature 910°C is probably due to minor formation of γ-iron. In the forming temperatures interval 650-950°C and strain rate 0.1-10 s-1 the flow stress curves were obtained and after their analysis hot deformation activation energy of 380 kJ·mol-1 was achieved. Peak stress and corresponding peak strain values were mathematically described with good accuracy by equations depending on Zener-Hollomon parameter.

2

Zmiany struktury stopu na osnowie fazy międzymetalicznej FeAl po odkształceniu plastycznym na gorąco

Jabłońska M., Bednarczyk I.

Hutnik, Wiadomości Hutnicze

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2013

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Vol. 80, nr 8

550--554

PL

W Katedrze Nauki o Materiałach Politechniki Śląskiej prowadzone są badania nad poznaniem zjawisk strukturalnych zachodzących podczas odkształcenia plastycznego na gorąco zmierzających do opracowania technologii obróbki cieplnoplastycznej stopów z układu Al-Fe. W artykule przedstawiono przebieg zmian strukturalnych stopu FeAl42 pod wpływem odkształcenia plastycznego na gorąco z zastosowaniem kilku wariantów temperatury procesu przy zadanej stałej prędkości odkształcenia 0,1 s-1. Badania wykonano na plastomerze skrętnym w zakresie temperatury 800°C÷1100°C. Przeprowadzono analizę zmian mikrostruktury i substruktury badanego stopu przy użyciu techniki mikroskopii świetlnej LM i skaningowo-transmisyjnej mikroskopii elektronowej STEM.

EN

Department of Materials Science at Silesian University of Technology conducts research to develop the knowledge about the structural phenomena which occur during hot plastic treatmentwhich are aimed at elaboration of a technology of heat and plastic treatment of selected alloys from Al-Fe system. The paper presents the course of structural changes of FeAl42 under the hot plastic deformation with application of a few different temperatures of the process at a constant strain rate value 0,1s-1. Tests were conducted on torsion plastometer in temperature range from 800°C to 1100°C. The analysis of the microstructure and substructure changes of tested alloy was conducted with using light microscopy LM and scanning-transmission electron microscopy STEM techniques.

3

Third generation of AHSS with increased fraction of retained austenite for the automotive industry

Grajcar A., Kuziak R., Zalecki W.

Archives of Civil and Mechanical Engineering

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2012

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Vol. 12, no. 3

334--341

EN

Third generation of advanced high-strength steels for the automotive industry contains a high volume fraction of fine-grained ferrite, carbide-free bainite, martensite and retained austenite. The level of strength and ductility is highly dependent on the fraction and mechanical stability of austenitic phase. One of the methods to obtain an increased fraction of γ phase is trough its chemical stabilization by Mn. Two 0.17C–3Mn–1.5Al–0.2Si–0.2Mo steels with and without Nb microaddition were developed in the present study. The steels were subjected to the thermomechanical processing designed on the basis of the DCCT diagram (deformation – continuous cooling transformation). The paper presents the results of the multi-stage compression tests and multiphase microstructures obtained as a result of the controlled multi-stage cooling. It was found that the hot workability of a new generation of AHSS is very challenging due to high values of flow stresses required. However, the thermomechanical processing enables to obtain very fine-grained bainite-based microstructures with a fraction of retained austenite up to 20%. The highest fraction of fine grains and interlath austenite was obtained for the temperature range between 400 and 450 °C. The effect of Nb results in higher flow stresses and better distribution of all the microstructural constituents.

4

Evaluation of Energy-Consuming of Elastic-Plastic Stiff Foam in Case of Huge Volumetric Deformation

Iwanowski A., Osiński J., Żach P.

Machine Dynamics Research

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2010

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Vol. 34, No. 2

37-43

EN

This paper presents an approach to describe a mathematical model of elastic - plastic stiff foam. Stress-strain curves obtained from real test were used to build a FEM model of tested foam: the "crushable foam" material has been used to define a mechanical properties. Main part of the article is devoted to numerical simulations in ABAQUS: static (uniaxial compression test) and dynamic (simulation of impact). The article presents also a possibility of usage of the tested foam in a bicycle with an energy-consuming body.

5

Opis procesu odkształcenia w warunkach zmęczenia cieplno-mechanicznego

Okrajni J., Marek A., Junak G.

Zeszyty Naukowe Politechniki Świętokrzyskiej. Nauki Techniczne

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2007

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Z. 4

98-100

PL

W pracy przedstawiono podstawowe założenia metody pozwalającej opisać zachowanie się materiałów w warunkach zmęczenia cieplno-mechanicznego, a także jej zastosowanie do wyznaczania charakterystyk zmęczenia wybranego materiału. Badania wykonano dla stali P91 wykorzystywanej w energetyce. Porównano wyniki uzyskane na podstawie badań z otrzymanymi przy wykorzystaniu zaproponowanego ujęcia matematycznego dla wybranych wartości kąta przesunięcia fazowego pomiędzy cyklem temperatury i odkształcenia całkowitego. Przedstawiona metoda umożliwia badanie wpływu relacji pomiędzy parametrami procesu zmęczenia na charakterystyki odkształcania w warunkach jednoosiowego stanu naprężenia.

EN

The problem addressed in the paper is the description of a deformation process under the mechanical and thermal loading. The mathematical modelling has been used to describe the stress-strain behaviour of materials. The method of fatigue testing has been adopted to determine experimentally stress-strain characteristics. The method based on the long term own experience in thermo-mechanical investigations and new European Code-of-Practice for Thermo-Mechanical Fatigue Testing. An appropriate model description has been developed. Fatigue examinations of the P91 steel that is used in power industry, were carried out. The validation of the model has been performed. So far, experimental verification of the usefulness of the model description to determine the stress-strain characteristics’ course for a selected value of the phase shift angle between the temperature and total strain cycles has been made. It has been found that the proposed model reflects the deformation process nature very well in variable temperature, strain and stress conditions.