Wyniki wyszukiwania - BazTech

1

Possibility of obtaining lanthanum doped nickel coatings from baths based on deep eutectic solvents

Niciejewska Anna, Tylus Włodzimierz, Marczewski Marek, Winiarska Katarzyna, Szczygieł Bogdan, Winiarski Juliusz

Ochrona przed Korozją

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2022

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nr 11

344--349

EN

Lanthanum-doped nickel coatings were obtained from the bath based on a deep eutectic solvent: choline chloride and propylene glycol, mixed in a molar ratio of 1 : 2, and 0.2 mol dm−3 NiCl2 ∙ 6H2O and 0.5 mol dm−3 LaCl2 ∙ xH2O. The morphology, topography and chemical composition were examined. The lanthanum content in the coating was determined to be 1.7 wt. % using the ICP-MS method. Lanthanum on the surface was mainly in the form of lanthanum carbonate. The obtained coating was exposed to a 7-day exposure in 0.05 mol dm−3 NaCl solution. The coating showed the highest corrosion resistance (Rp ~ 30 kΩ cm2) after 15 hours of exposure to the NaCl solution.

PL

Powłoki niklowe domieszkowane lantanem zostały otrzymane z kąpieli na bazie rozpuszczalnika eutektycznego chlorku choliny i glikolu propylenowego zmieszanych w proporcjach molowych 1 : 2 oraz 0,2 mol dm−3 NiCl2 ∙ 6H2O i 0,5 mol dm−3 LaCl2 ∙ xH2O. Zbadano morfologię, topografię oraz skład chemiczny. Zawartość lantanu w powłoce została określona na 1,7% mas. techniką ICP-MS. Na powierzchni powłoki lantan występował głównie w postaci węglanu lantanu. Otrzymana powłoka została poddana 7-dniowej ekspozycji w 0,05 mol dm−3 roztworze NaCl. Największą odporność na korozję powłoki stwierdzono po 15-godzinnej ekspozycji w roztworze NaCl.

2

Fabrication and amplified spontaneous emission behavior of FAPbBr3 perovskite quantum dots in solid polymer rods

Khan M. Naziruddin, Almohammedi Abdullah

Materials Science Poland

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2022

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Vol. 40, No. 1

84--100

EN

Formamidinium lead tribromide (FAPbBr3) perovskite quantum dot (PQ-Dot) solution was incorporated in a polymer sol, which was used to fabricate solid nanocomposite rods and disks. The solid nanocomposite samples were studied by different characterization techniques. The absorption, emission, and excitation spectra of the PQ-Dot in the solid rods/disks were quite significant as compared to the spectra of the PQ-Dot solution. Scanning electron microscopy (SEM) was used to inspect the structural morphology of the PQ-Dot in the solid environment. The PQ-Dot particles were evidently present in the solid matrix and were confirmed by the SEM images and energy dispersive X-ray spectroscopy (EDX) spectra. The size of the PQ-Dots was examined by transmission electron microscopy (TEM). The majority of the particles were about 3–8 nm in size. The spontaneous and stimulated emission profiles of the solid composite rods/disks were studied using pumping energy ranging from 2 μJ to 18 μJ from a high-power picosecond neodymium-doped yttrium aluminum garnet (Nd:YAG) tunable laser system. The observed emission signal was quite significant. The emission peak of the PQ-Dot solution had a slight change when it was included in the solid matrix. Amplified spontaneous emission (ASE) behavior was obtained from the PQ-Dot composite rod. The ASE peaks were quite steady at different levels of excitation energy. ASE was achieved at low threshold energy. The composite rod with ASE behavior indicates that it is a promising composite material that can be used to achieve lasing in the future. The ASE obtained from the composite rods/disks may improve to achieve lasing if a high concentration of PQ-Dot solution is used in the matrix.

3

The modern approach to manufacturing of carbon-rhenium nanocomposites

Dobrzańska-Danikiewicz A. D., Wolany W.

Journal of Achievements in Materials and Manufacturing Engineering

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2022

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Vol. 115, nr 2

57--63

EN

Purpose: The aim of the paper is to present the high-temperature method of producing MWCNTs-Re nanocomposites, the selection of satisfactory production conditions and the presentation of the results of microscopic and spectroscopic studies of nanocomposites produced by this method. Design/methodology/approach: Two methods of manufacturing carbon-rhenium nanocomposites were tested: ineffective chemical synthesis and high-temperature reduction using H2, which was proven successful and allowed the production of nanocomposites with the expected properties. The received nanocomposites were investigated using Transmission Electron Microscope (TEM), and Scanning Electron Microscope (SEM), as well as were subjected to spectroscopic examination. Findings: The article presents three steps of MWCNTs-Re nanocomposites fabrication using the high-temperature method, functionalization, impregnation and reduction. As part of own work, satisfactory conditions for producing those nanocomposites using a materials science and heuristic analysis were selected. Research limitations/implications: The proposed high-temperature method allows to join rhenium nanoparticles with MWCNTs permanently. It is reasonable to test in the future whether the method is also effective for other carbon nanomaterials and/or nanoparticles of other metals. Practical implications: MWCNTs-Re nanocomposites can be used as sensors of gases that are harmful to the environment. It was also confirmed that the MWCNTs-Re_4 nanocomposite has catalytic properties. Originality/value: The paper presents a modern approach to the manufacturing of MWCNTs-Re nanocomposites, which assumes the use of a high-temperature furnace to heat the material in a hydrogen atmosphere.

4

SEM/TEM Investigation of Degradation of Bi-Layer (Cr,Al)N/Cr2N3 Duplex Coatings Exposed to AlSi Alloy High Pressure Die Casting Cycles

Wilczek A., Morgiel Jerzy, Sypień Anna, Pomorska Małgorzata, Rogal Łukasz

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 4

1341--1348

EN

High pressure die casting (HDPC) allows to produce aluminum parts for car industry of complicated shapes in long series. Dies used in this process must be robust enough to withstand long term injection cycling with liquid aluminum alloys, as otherwise their defects are imprinted on the product making them unacceptable. It is expected that nitriding followed by coating deposition (duplex treatment) should protect them in best way and increase intervals between the cleaning/repairing operations. The present experiment covered investigations of the microstructure of the as nitride and deposited with CrAlN coating as well as its shape after foundry tests. The observations were performed with the scanning and transmission electron microscopy (SEM/TEM) method. They showed that the bottom part of this bi-layer is formed by roughly equi-axed Cr2N crystallites, while the upper one with the fine columnar (CrAl)N crystallites. This bi-layers were matched with a set of 7x nano-layers of CrN/(CrAl)N, while at the coating bottom a CrN buffer layer was placed. The foundry run for up to 19 500 cycles denuded most of coated area exposed to fast liquid flow (40 m/s) but left most of bottom part of the coating in the areas exposed to slower flow (7 m/s). The acquired data indicated that the main weakness of this coating was in its porosity present both at the columnar grain boundaries (upper layer) as well as at the bottom of droplets imbedded in it (both layers). They nucleate cracks propagating perpendicularly and the latter at an angle or even parallel to the substrate. The most crack resistant part of the coating turned-out the bottom layer built of roughly equiaxed fine Cr2N crystallites. Even application of this relatively simple duplex protection in the form of CrAlN coating deposited on the nitride substrate helped to extend the die run in the foundry by more than three times.

5

Modelowanie modułów termoelektrycznych w programie SPICE - przegląd

Posobkiewicz Krzysztof, Górecki Krzysztof

Przegląd Elektrotechniczny

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2021

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R. 97, nr 2

1--5

PL

W artykule przedstawiono wyniki badań dwóch literaturowych modeli modułów termoelektrycznych dedykowanych dla programu SPICE. Przedstawiono topologię oraz równania opisujące te modele. Pokazano także wyniki weryfikacji ich dokładności poprzez porównanie wyników pomiarów i obliczeń wykonanych w programie SPICE. Niezbędne wartości parametrów wyznaczono w oparciu o dane producenta.

EN

In the paper results of research of two published in literature SPICE models of thermoelectric modules have been presented. Topology and equations describing these models, as well as results of experimental verification of their accuracy, based on comparison of results of SPICE calculation and measurements have been discussed. Required models parameters values have been calculated using manufacturer data.

6

Synthesis, spectroscopic and thermogravimetric interpretations of UO2(II), ZrO(II), Zr(IV), VO(II) and V(V) ciprofloxacin antibiotic drug complexes

Albedair Lamia A.

Polish Journal of Chemical Technology

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2021

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Vol. 23, nr 1

45--52

EN

New five ciprofloxacin (CIP) complexes of dioxouranium(II), oxozirconium(II), zirconium(IV), oxovanadium(II) and vanadium(IV) in the proportion 1:2 have been prepared using CIP as a drug chelate with UO2(NO3)2. 6H2O, ZrOCl2. 8H2O, ZrC4, VOSO4. xH2O and V2O5 respectively. The CIP complexes have been characterized based on the elemental analysis, molar conductance, magnetic, (FTIR & 1HNMR) spectral and thermal studies. The molar conductance studies of the synthesized complexes in DMSO solvent with concentration of 10–3 M indicate their non-electrolytic properties. At room temperature, the magnetic moment measurements revealed a diamagnetic behavior for all CIP prepared complexes. The different formulas of the new complexes can be represented as [UO2(CIP)2(NO3)2] (I), [VO(CIP)2(SO4)(H2O)] (II), [V2(O)(O2)2(CIP)2] (III), [Zr(O)(CIP)2(Cl)2] (IV), and [Zr(CIP)2(Cl)4] (V). The thermal analysis data of the complexes indicates the absence of coordinated water molecules except for vanadyl(II) complex (II). The CIP chelate is a uni-dentate ligand coordinated to the mentioned metal ion through terminal piperazinyl nitrogen. The transmission electron microscopy (TEM) investigation confirms the nano-structured form of the complexes.

7

In situ thermal decomposition route: Preparation and characterization of nano nickel, cobalt, and copper oxides using an aromatic amine complexes as a low-cost simple precursor

Refat Moamen S., Mohamed Soha F., Altalhi Tariq A., Bakare Safyah B., Al-Hazmi Ghaferah H.

Polish Journal of Chemical Technology

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2021

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Vol. 23, nr 2

47--53

EN

The main interest now is the development of metallic or inorganic-organic compounds to prepare nanoparticle materials. The use of new compounds could be beneficial and open a new method for preparing nanomaterials to control the size, shape, and size of the nanocrystals. In this article, the thermal decomposition of [M2(o-tol)2(H2O)8]Cl4 (where o-tol is ortho-tolidine compound, M = Ni2+, Co2+, Cu2+) new precursor complex was discussed in solid-state conditions. The thermal decomposition route showed that the synthesized three complexes were easily decomposed into NiO, Co3O4 and CuO nanoparticles. This decomposition was performed at low temperatures (~600°C) in atmospheric air without using any expensive and toxic solvent or complicated equipment. The obtained product was identified by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX). FT-IR, XRD and EDX analyses revealed that the NiO nanoparticles exhibit a face-centered-cubic lattice structure with a crystallite size of 9–12 nm. The formation of a highly pure spinel-type Co3O4 phase with cubic structure showed that the Co3O4 nanoparticles have a sphere-like morphology with an average size of 8–10 nm. The XRD patterns of the CuO confirmed that the monoclinic phase with the average diameter of the spherical nanoparticles was approximately 9–15 nm.

8

The qualitative-quantitative approach to microstructural characterization of nanostructured bainitic steels using electron microscopy methods

Królicka Aleksandra, Janik Aleksandra, Żak Andrzej, Radwański Krzysztof

Materials Science Poland

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2021

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Vol. 39, No. 2

188-199

EN

Both qualitative and quantitative analyses play a key role in the microstructural characterization of nanobainitic steels focused on their mechanical properties. This research demonstrates various methods of microstructure analysis using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD) techniques, taking into account these two approaches. The structural constituents have been qualitatively characterized using TEM and selected area electron diffraction (SAED), together with quantitative analysis based on the misorientation angle (EBSD). Besides, quantitative measurement of austenite with both blocky and film-like morphologies has been carried out. Due to the scale of nanostructured bainite, it is also important to control the thickness of bainitic ferrite and film-like austenite; hence, a method for measuring their thickness is presented. Finally, the possibility of measuring the prior-austenite grain size by the EBSD method is also demonstrated and compared with the conventional grain boundary etching method. The presented methods of qualitative and quantitative analyses form a complementary procedure for the microstructural characterization of nanoscale bainitic steels.

9

Mechanisms of plastic deformation in light high-manganese steel of TRIPLEX type

Sozańska-Jędrasik Liwia, Borek Wojciech, Mazurkiewicz Janusz

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 5

art. no. e137412

EN

In this scientific publication, research results of two newly developed hot-rolled Fe-Mn-Al-C (X105) and Fe-Mn-Al-Nb-Ti-C (X98) types of steel were compared. These types of steel are characterized by an average density of 6.68 g/cm³, a value 15% lower compared to conventional structural steel. Hot rolling was carried out on a semi-industrial line to evaluate the effect of hot plastic deformation conditions with different cooling variants on the structure. The detailed analysis of phase composition as well as microstructure allows us to state that the investigated steel is characterized by an austenitic-ferritic structure with carbides precipitates. The results of the transmission electron microscopy (TEM) tests of both types of steel after hot rolling showed the occurrence of various deformation effects such as shear bands, micro bands, and lens twins in the microstructure. Based on the research undertaken with the use of transmission electron microscopy, it was found that the hardening mechanism of the X98 and X105 steel is deformation-induced plasticity by the formation of shear bands (SIP) and micro shear bands (MBIP).

10

Wire-feed assisted A-TIG welding of dissimilar steels

Sharma Pratishtha, Dwivedi Dheerendra Kumar

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 2

672--691

EN

This study investigates the activated flux-tungsten inert gas welding (A-TIG) welding of dissimilar P92 steel-304H ASS using ‘wire feed’ (patent pending) in terms of weld pool mixing behavior, microstructure and mechanical properties of the weld joint. ErNiCrMo-3 wire was fed during welding and three-wire feeding configurations were analyzed in view of filler wire melting and weld pool mixing behavior. The metal from filler wire is transferred into the weld pool in the form of ‘interrupted liquid bridge’ and ‘uninterrupted liquid bridge.’ The ‘uninterrupted liquid bridge’ melting resulted in homogeneous mixing of filler wire into the weld pool. The weld joint produced using the best wire feeding configuration was characterized and compared with the weld joint developed without wire feed. Microstructure alterations were realized with the use of wire feed. The weld zone with wire feed exhibited a fully austenitic structure, whereas; the completely martensitic structure was obtained using A-TIG welding without wire feed. The microstructural transformation led to the improvement of ductility and impact toughness of weld joint without substantial loss of tensile strength. The total elongation and impact toughness of the A-TIG weld joint with wire feed was 45.9% and (89 ± 2) J, respectively, which were significantly higher in contrast to the A-TIG weld joint without wire feed [total elongation: 37.4% and impact toughness: (30 ± 2) J].

11

Assessment of changes in microstructure and hardness of bearing steel for operation at a high temperature caused by short-term overheating

Łęczycki Krzysztof, Gronek Sebastian

Journal of KONBiN

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2020

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Vol. 50, iss. 4

89--110

EN

The paper presented research results of the impact of short-term overheating of samples collected from the outer bearing ring suitable for the operation at elevated temperature installed in the turbine engine on the microstructure and hardness of the material. The samples were annealed at the following temperatures: 500, 600, 700, 800, 900 and 1000°C; and then cooled in still air. Microstructure examinations were conducted under metallographic microscope and transmission electron microscope.

PL

W publikacji przedstawiono wyniki badań wpływu krótkotrwałego nagrzewania próbek pobranych z pierścienia zewnętrznego łożyska przeznaczonego do pracy w podwyższonej temperaturze z silnika turbinowego na mikrostrukturę oraz twardość jego materiału. Próbki wygrzewano w temperaturach: 500, 600, 700, 800, 900 i 1000°C, następnie studzono na spokojnym powietrzu. Badania mikrostruktury przeprowadzono, wykorzystując mikroskop metalograficzny oraz transmisyjny mikroskop elektronowy.

12

Corrosion Resistance of the Nanostructured X37CrMoV5-1 Steel

Skołek E., Kamiński J., Marciniak S., Świątnicki W. A.

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 1

133--140

EN

The aim of this study is to compare the corrosion resistance of X37CrMoV5-l tool steel after nanostructurization and after a conventional heat treatment. The nanostructuring treatment consisted of austempering at 300°C, which produced a microstructure composed of nanometric carbide-free bainite separated by nanometric layers of retained austenite. The retained austenite occurred also in form of blocks which partially undergo martensitic transformation during final cooling. For comparison, a series of steel samples were subjected to a standard quenching and high tempering treatment, which produced a microstructure of tempered martensite. The obtained results showed that the corrosion resistance of steel after both variants of heat treatment is similar. The results indicate that the nanocrystalline structure with high density of intercrystalline boundaries do not deteriorate the corrosion resistance of steel, which depends to a greater extent on its phase composition.

13

Superplastic deformation of Mg–9Li–2Al–0.5Sc alloy after grain refinement by KoBo extrusion and cyclic forging

Dutkiewicz Jan, Kalita Damian, Maziarz Wojciech, Faryna Marek

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 4

343--353

EN

The quaternary Mg–9Li–2Al–0.5Sc alloy (in wt%) was prepared from pure components. After homogenization, the alloy was subjected to severe plastic deformation by KoBo extrusion and cyclic forging leading to grain refinement in the range of 0.5–2 µm of hexagonal close-packed (HCP) α phase. Deformed alloys showed high ultimate tensile strength near 200 MPa and good elongation in the range 30–40% at room temperature (RT). Large elongations close to 200% were obtained during the tensile test at a temperature of 200 °C. Deformed samples showed the presence of multiple voids confirming grain boundary sliding mechanism of deformation. Twins on {101-2} planes were identified using electron backscatter diffraction analysis, being in a good agreement with the earlier observation of Mg–Li and Mg–Sc alloys. Intermetallic phases such as cubic MgSc were identified in deformed alloys mostly within HCP α phase, whereas HCP MgSc2 particles were observed within body-centered cubic (BCC) β phase. Intermetallic phases were responsible for RT strengthening of alloys and slightly lower tensile elongation during superplastic deformation. Formation of the HCP α phase was observed within the BCC β phase in tensile deformed alloys. Atomic-level nucleation of HCP phase within the β phase was identified by the use of high-resolution transmission electron microscopy technique.

14

Application of nanoindentation to evaluate the hardness and yield strength of brass joints produced by FSW: microstructural and strengthening mechanisms

Heidarzadeh A., Paidar M., Güleryüz G., Barenji R. Vatankhah

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 2

158--166

EN

Nanoindentation test was employed to measure the actual hardness and yield strength of the stir zone in the friction stir-welded single-phase brass joints. For this aim, different joints were prepared according to an experimental matrix based on the central composite rotatable design. In this design matrix, the tool rotational speed, tool traverse speed, and tool axial force were the input parameters. The outputs were the hardness and yield strength of the joints. To measure the hardness and tensile strength of the joints, the nanoindentation test was employed. Moreover, electron back scattered diffraction and transmission electron microscopy techniques were used to study the microstructural features. The results showed that by decreasing rotational speed and axial force, and by increasing the traverse speed, the hardness and yield strength of the joints were increased. In other words, lower heat inputs caused higher strength in the joints. Finer grain sizes, larger grain average misorientation amounts, i.e., existence of more dislocations, and greater Taylor factors in the lower heat input joints revealed that the influence of grain boundaries, dislocations, and texture were the origins of better mechanical properties.

15

Microstructure and Phase Composition of the Ag-Al Film Wear Track: Through-Thickness Characterization by Advanced Electron Microscopy

Kryshtal O., Kruk A., Mao F., Taher M., Jansson U., Czyrska-Filemonowicz A.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 1

251--256

EN

Analytical transmission electron microscopy has been applied to characterize the microstructure, phase and chemical composition of the Ag–Al wear track throughout its thickness down to the atomic level. Microscopy findings have been correlated with Ag–Al film tribological properties to understand the effect of the hexagonal solid solution phase on the tribological properties of this film. Ag–25Al (at.%) films have been produced by simultaneous magnetron sputtering of components in Ar atmosphere under 1 mTorr pressure and subjected to pin-on-disc tribological tests. It has been shown that hcp phase with (001) planes aligned parallel to the film surface dominates both in as-deposited and in tribofilm areas of the Ag–Al alloy film. Possible mechanisms of reduced friction in easily oxidized Ag–Al system are discussed and the mechanism based on readily shearing basal planes of the hcp phase is considered as the most probable one.

16

Microstructural and Chemical Composition Changes in the Bonding Zone of Explosively Welded Sheets

Paul H., Miszczyk M. M., Gałka A., Chulist R., Szulc Z.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 2

683--694

EN

In this work, the effect of heat transfer during explosive welding (EXW) and post-processing annealing on the microstructural and chemical composition changes have been thoroughly analysed using scanning and transmission electron microscopies and X-ray synchrotron radiation. Several combination of explosively welded metal compositions were studied: Ti with Al, Cu with Al, Ta or stainless steel, stainless steel with Zr or Ta and Ti with carbon steel. It was found that the melted metals exhibit a strong tendency to form brittle crystalline, nano-grained or even amorphous phases during the solidification. For all analysed metal combinations most of the phases formed in the zones of solidified melt do not appear in the equilibrium phase diagrams. Concurrently, the interfacial layers undergo severe plastic deformation forming nano-grained structures. It has been established that these heavily deformed areas can undergo dynamic recovery and recrystallization already during clad processing. This leads to the formation of new stress-free grains near the interface. In the case of low temperature and short time post processing annealing only the melted zones and severely deformed layers undergo recovery and recrystallization. However, drastic changes in the microstructure occurs at higher temperature and for longer annealing times. Applying such conditions leads to diffusion dominant processes across the interface. As a consequence continuous layers of intermetallic phases of equilibrium composition are obtained.

17

Influence of Different Plants Extracts on Silver Nanopar ticles Green Synthesis

Velgosova O., Mražíková A., Veselovský L., Willner J., Fornalczyk A.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 2

665--670

EN

Three plants extracts were used for biosynthesis of Ag nanoparticles (AgNPs). AgNPs nucleation process requires effective reduction agents which secure Ag+ to Ag0 reduction and also stabilizing/capping agents. The UV-vis and TEM observation revealed that the best results were obtained by R. officinalis leaf extract. The strong SPR band peak appeared at the wavelength 418 nm. Synthetized AgNPs were globular, fine (~20 nm), uniform and stabile throughout the experiment. A rapid rate of AgNPs synthesis was also significant and economically advantageous factor. Fine (10-20 nm) and globular nanoparticles were synthetized also by U. dioica leaf extract, but the stability of nanoparticles was not permanent. Despite V. vitis-idaea fruit extract contains a lot of reducing agents, UV-vis did not confirm the presence of AgNPs in solution. Synthetized Ag particles were very unstable, Ag particles agglomerated very fast and clearly indicated sediment was formed.

18

Tensile behavior, microstructure, and substructure of the friction stir welded 70/30 brass joints: RSM, EBSD, and TEM study

Heidarzadeh Akbar

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 1

137--146

EN

The effect of bead on plate friction stir welding parameters on the tensile properties of the 70/30 brass joints was investigated using response surface method. The microstructures of the joints were characterized using optical microscopy, electron backscattered diffraction (EBSD), and transmission electron microscopy (TEM). The tensile test was conducted to measure the ultimate tensile strength and elongation of the joints. In addition, the fracture surfaces of the tensile specimens were analyzed by scanning electron microscopy (SEM). The results showed that the most effective parameters on the strength and elongation of the joints were tool rotational speed and axial force, respectively. Optimizing the parameters revealed that the maximum strength and elongation of 318.5 MPa and 54.9% can be achieved at a rotational speed of 1000 rpm, a traverse speed of 58.4 mm/min, and an axial force of 3 kN. The strengthening mechanisms of grain boundary and dislocation density effects were responsible for the higher ultimate tensile strength of the joints welded at the lower heat input conditions. Furthermore, the effect of friction stir parameters on the ultimate tensile strength and elongation of the joints has been discussed, thoroughly.

19

Microstructure, grain refinement and hardness of Al–3%Mg aluminium alloy processed by ECAP with helical die

Snopiński Przemysław, Tański T., Matus K., Rusz S.

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 2

287--296

EN

In the present research, commercial Al–3%Mg aluminium alloy was subjected to the ECAP processing using a modified die with a helical 30° exit channel. The changes in microstructure were characterized by light microscopy, electron backscatter diffraction (EBSD) and TEM. Mechanical properties were compared based on hardness measurement. It is also shown that such modification of ECAP die enhances grain refinement due to the vortex-like flow of metal during subsequent deformations. The results of the metallographic study showed that microstructure is refined due to the interactions and intersections of the deformation bands. The mechanical properties examinations display a significant improvement after the first ECAP pass and less significant increase with subsequent passes.

20

Własności i struktura stali S235JR po statycznym i dynamicznym przeginaniu i prostowaniu na zimno

Rdzawski Z., Głuchowski W., Sobota J., Pacyna J., Dąbrowski R., Rożniata E.

Obróbka Plastyczna Metali

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2018

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T. 29, nr 2

151--168

PL

Bardzo często w okresach kryzysów gospodarczych pojawiają się uciążliwe niedomagania w zakresie utrzymania produkcji na odpowiednim poziomie ilościowym oraz jakościowym zapewniającym stały rozwój. Podołanie rosnącym potrzebom wymaga znacznego wysiłku w zapewnieniu pożądanego zespołu cech użytkowych przy zachowaniu odpowiedniej ekonomiki wytwarzania. Z tymi problemami, szczególnie w ostrej formie, spotykają się przedsiębiorstwa wyposażone w przestarzałe urządzenia produkcyjne, które swoją szansę na przeżycie upatrują w doskonaleniu procesów technologicznych opartych o wiedzę. Rosnące zapotrzebowanie na funkcjonalne stopy miedzi, charakteryzujące się takimi szczególnymi zespołami własności użytkowych, jak korzystna kombinacja wysokich własności mechanicznych oraz konduktywności elektrycznej i cieplnej, stabilne właściwości w warunkach eksploatacyjnych, odporność na korozję oraz zużycie ścierne, odporność na zmienne obciążenia mechaniczne, cieplne i prądowe. Spełnienie tych oczekiwań wymaga dobrania odpowiednich składników stopowych miedzi jak też technologii osiągania odpowiedniej i stabilnej struktury stopów. Dotyczy to głównie stopów miedzi podatnych do utwardzania wydzieleniowego, dyspersyjnego, roztworowego oraz umacniania odkształceniowego. Szczególną uwagę przywiązuje się do wytwarzania silnie rozdrobnionej struktury stopów (ultrafine grain size – UFG). Jedną z metod osiągania silnie rozdrobnionej struktury jest cykliczne przeginanie i prostowanie (continous repetitive corrugation and straightening – CRCS). Metodę tę wykorzystano z powodzeniem do zdecydowanej poprawy własności taśm z miedzi chromowej, podatnej do utwardzania wydzieleniowego, dla stopu CuNi2Si1 oraz dla brązu cynowego i mosiądzów. Otrzymane rezultaty stanowiły pewną zachętę do wykorzystania metody przeginania i prostowania dla metali o sieci regularnej, przestrzennie centrowanej A2. W tym celu do badań wybrano pręty walcowane na gorąco o przekroju 12x12 mm ze stali w gat. S235JR. Ze względu na wymiary prętów oraz dostępność urządzenia do przeginania i prostowania ograniczona została liczba cykli oraz zwiększono wartość odkształcenia i naprężenia.

EN

The periods of economic crises very often see serious problems in the maintenance of production at the appropriate quantitative and qualitative level as required for constant development. To meet the growing needs it is necessary to put considerable effort in ensuring the desired set of functional properties while maintaining adequate production economics. Those problems, especially in a severe form, are encountered by companies equipped with outdated production facilities, the companies which see their chance of survival in improvement of production processes based on the knowledge. There is a growing demand for functional copper alloys characterized by specific sets of functional properties such as advantageous combination of high mechanical properties with electrical and thermal conductivity, stable properties in operating conditions, resistance to corrosion and abrasive wear, resistance to changing mechanical, thermal and current loads. Meeting these expectations requires selection of appropriate copper alloy components as well as a relevant technology to achieve adequate and stable structure of alloys. This applies mainly to copper alloys which are susceptible to precipitation, dispersion, solution and strain hardening. Particular attention is paid to production of a highly fragmented structure of alloys (ultrafine grain size – UFG). One of the methods for production of highly fragmented structure consists of continuous repetitive corrugation and straightening (CRCS). This method was successfully applied for significant improvement of properties of copper alloys strips. The produced results provided some incentive to apply the method of corrugation and straightening to metals with body centred A2 lattice. For this purpose, hot-rolled S235JR steel grade rods of 12x12 mm section were used. Because of the dimensions of the rods and availability of corrugation and straightening equipment the number of cycles was reduced while the values of stress and strain were increased.