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Analysis of the static and dynamic properties of wear-resistant Hardox 600 steel in the context of its application in working elements

Konat Ł., Jasiński R., Białobrzeska B., Szczepański Ł.

Materials Science Poland

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2021

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Vol. 39, No. 1

86--102

EN

The article discusses the static and dynamic properties of high-strength, boron-containing Hardox 600 steel that is resistant to abrasive wear, both in its delivery state and after normalization. Since the available published material in the literature does not have any real mechanical indicators of the abovementioned steel, a static tension test was carried out at an ambient temperature. The steel’s tensile strength, yield strength, Young’s modulus, elongation and reduction of area were determined from the test. The Charpy impact test at temperatures of −40 °C, −20 °C, 0 °C, and +20 °C and fractographic analysis were performed to determine the transition temperature of ductility to brittleness. In dynamic load conditions, the assigned values of impact energy do not always truly determine the material behavior. Thus, the aim of the fractography was to provide precision when determining the behavior. A significant difference in the impact energy of the tested steel with respect to its heat treatment and ductile-brittle transition temperature was observed and determined based on the impact test result, as well as the nature of the fracture. On the basis of the determined structural and strength characteristics, an analysis of the possibility of application of Hardox 600 steel on selected elements of working machines was performed.

2

Research on the Mechanism and Kinetics of Polymorphic Transitions of ε CL-20 in Composite Systems

Guo X.-Y., Zhang P., Xu J.-J., Wang Z.-H., Jiao Q.-J.

Central European Journal of Energetic Materials

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2015

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Vol. 12, no. 4

689--702

EN

In order to explore the polymorphic transition law for ε-CL-20 in composite systems, the polymorphic transition process of pure ε-CL-20 crystals stimulated by heat was investigated by the X-ray Diffraction (XRD) method, and the kinetic parameters of the polymorphic transition process were calculated (including the apparent activation energy Ea and the pre-exponential factor lnA). Meanwhile the effects of different additives on the polymorphic transition process and kinetics of ε-CL-20 were explored in detail. The experimental results showed that the ε-form tends to transform into the γ- form on heating and that the Ea and lnA for the transition process were 209.97 kJ/mol and 57.47, respectively. The first group of additives clearly promoted the polymorphic transition of ε-CL-20 and lowered the initial transition temperature and the activation energy. The second and third groups of additives inhibited the polymorphic transition of ε-CL-20 and raised the initial transition temperature and the activation energy.

3

Application of Small Punch Test Method in Studies of the 14MoV63 Steel Before and After Revitalisation

Kłaput J.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 1

47--50

EN

The paper presents the results of studies of the chromium-molybdenum-vanadium steel designed for operation at elevated temperatures. The material was examined after long-term operation and after the revitalising heat treatment. Studies were performed by conventional methods and small punch test. Curves of ductile-brittle transition were plotted from the Charpy V-notch impact tests and were next compared with the curves of sudden loss of ductility obtained in the small punch test. Additionally, for the material before and after revitalisation, the values of temperatures Tpk and Tnuc were calculated using the method of inflection point.

PL

W pracy przedstawiono wyniki badań stali chromowo-molibdenowo-wanadowej przeznaczonej do pracy przy podwyższonych temperaturach. Materiał badano w stanie po wieloletniej eksploatacji i po obróbce cieplnej rewitalizującej. Badania prowadzono z zastosowaniem metod konwencjonalnych oraz przy pomocy metody small punch. Sporządzono krzywe przejścia plastyczno-kruchego z próby udarności Charpy V i porównano je z krzywymi nagłej utraty ciągliwości z próby small punch. Dla materiału przed i po rewitalizacji określono wartości temperatur Tpk i Tnuc stosując metodę punktu przegięcia.

4

Ab-initio studies of thermal and superconducting properties of HfX2 alloys (X = Tc, Re, and Os)

Sathyakumari V S, Sankar S, Mahalakshmi K

Materials Science Poland

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2014

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Vol. 32, No. 3

324--330

EN

A systematic study of thermal properties such as the Debye temperature, specific heat coefficient, Gruneisen constant, electron-phonon coupling constant and transition temperature have been carried out using the results of electronic band structure and related characteristics, for hafnium superconducting alloys, namely, HfTc2, HfRe2 and HfOs2. Computation of the electronic band structure and associated properties has been carried out using the tight-binding-linear-muffin-tin-orbital (TBLMTO) method within atomic sphere approximation (ASA). The calculated values have been compared with the available results of literature data.

5

Rationalisation of austenite transformation to upper or lower bainite in steels

Ławrynowicz Z.

Advances in Materials Science

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2014

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Vol. 14, nr 2(40)

14--23

EN

The paper presents an analytical evaluation of transition temperature from upper to lower bainite in Fe-C-Cr steel. The calculations was based on the model constructed by Matas and Hehemann which involves a comparison between the times needed to precipitate cementite within the bainitic ferrite plates (tθ), with the time required to decarburise supersaturated ferrite plates (td). The transition between upper and lower bainite is found to occur over a narrow range of temperatures (350-410°C) and depends on the thickness of bainitic ferrite laths and the volume fraction of precipitated cementite. On comparing the td and tθ times it was found that the transition temperature from upper to lower bainite reaction (LS) of about 350oC could be predicted if the thickness of bainitic ferrite laths is set as wo = 0.1 μm and volume fraction of cementite is set as ξ = 0.01.

6

Band Structure of Ruthenate Superconductors

Dow J., Zolotovsky A.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2011

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Vol. 15, No 1

99-105

EN

We investigate the band structure of ruthenates using the first-principles method of density functional theory (DFT). We calculated the band structure and density of states at the Fermi level for superconductors Ba2YRuO6 and Sr2YRuO6. Our calculations show that the maximum critical superconducting transition temperature Tc=93K can be obtained for Ba2YRuO6.

7

Synthesis of nanocrystalline rutile-phase titania at low temperatures

Santos J. G., Ogasawara T., Correa R. A.

Materials Science Poland

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2009

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Vol. 27, No. 4/1

1067--1076

EN

Anatase and rutile are the predominant phases in titanium dioxide. In many cases, rutile stable phase is the desired product material, but at low temperatures methods of synthesis (aqueous route) produce metastable anatase as a major product that reverts to rutile only when heated up to 1000°C. Calcination for obtaining rutile phase is the greatest energy demanding step for titanium dioxide production by the sulphate process, and is responsible for almost 60% of total energy consumption. In this work, an innovative technique involving a sonication pre-treatment in acid medium was developed to change particle reactivity and accelerate the anatase-to-rutile transformation. Scanning electron micrographs and surface area measurements confirmed the alteration in texture and porosity of the powders. Results indicate that it is possible to obtain 100% of rutile phase at temperatures as low as 430°C.