Wyniki wyszukiwania - BazTech

1

Effect of Nb and Ti micro-additives and thermo-mechanical treatment of high-manganese steels with aluminium and silicon on their microstructure and mechanical properties

Sozańska-Jędrasik L., Mazurkiewicz J., Borek W., Matus K., Chmiela B., Zubko M.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 1

133--142

EN

The results are based on two experimental high-manganese X98MnAlSiNbTi24-11 and X105MnAlSi24-11 steels subjected to thermo-mechanical treatment by hot-rolling on a semi-industrial processing line. The paper presents the results of diffraction and structural studies using scanning and transmission electron microscopy showing the role of Nb and Ti micro-additives in shaping high strength properties of high-manganese austenitic-ferritic steels with complex carbides. The performed investigations of two experimental steels allow to explain how the change cooling conditions after thermo-mechanical treatment of the analysed steels affects the change of their microstructure and mechanical properties. The obtained results allow assessing the impact of both the chemical composition and the applied thermo-mechanical treatment technology on the structural effects of strengthening of the newly developed steels.

2

Effect of plastic deformation rate at room temperature on structure and mechanical properties of high-Mn austenitic Mn-Al-Si 25-3-3 type steel

Borek W., Lis M., Gołombek K., Sakiewicz P., Piotrowski K.

Archives of Materials Science and Engineering

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2019

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Vol. 96, nr 1

22--31

EN

Purpose: The aim of the paper is to determine influence of plastic deformation rate at room temperature on structure and mechanical properties of high-Mn austenitic Mn-Al-Si 25-3-3 type steel tested at room temperature. Design/methodology/approach: Mechanical properties of tested steel was determined using Zwick Z100 static testing machine for testing with the deformation speed equal 0.008 s-1, and RSO rotary hammer for testing with deformation speeds of 250, 500 and 1000s-1. The microstructure evolution samples tested in static and dynamic conditions was determined in metallographic investigations using light microscopy as well as X-ray diffraction. Findings: Based on X-ray phase analysis results, together with observation using metallographic microscope, it was concluded, that the investigated high-Mn X13MnAlSiNbTi25-3-3 steel demonstrates austenitic structure with numerous mechanical twins, what agrees with TWIP effect. It was demonstrated, that raise of plastic deformation rate produces higher tensile strength UTS and higher conventional yield point YS0.2. The UTS strength values for deformation rate 250, 500 and 1000 s-1 grew by: 35, 24 and 31%, appropriately, whereas in case of YS0.2 these were: 7, 74 and 130%, accordingly, in respect to the results for the investigated steel deformed under static conditions, where UTS and YS0.2 values are 1050 MPa and 700 MPa. Opposite tendency was observed for experimentally measured uniform and total relative elongation. Homogeneous austenitic structure was confirmed by X-ray diffractometer tests. Research limitations/implications: To fully describe influence of strain rates on structure and mechanical properties, further investigations specially with using transmission electron microscope are required. Practical implications: Knowledge about obtained microstructures and mechanical properties results of tested X13MnAlSiNbTi25-3-3 steel under static and dynamic conditions can be useful for the appropriate use of this type of engineering material in machines and equipment susceptible to static or dynamic loads. Originality/value: The influence of plastic deformation at room temperature under static and dynamic conditions of new-developed high-manganese austenitic X13MnAlSiNbTi25-3-3 steels were investigated.

3

Combined effects of strain and cooling path on hot deformation response and microstructure of low-carbon structural steel

Morawiec M., Borek W., Mroziński M., Grajcar A.

Archives of Materials Science and Engineering

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2019

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Vol. 95, nr 1

5--11

EN

Purpose: The aim of the paper is to analyse the effect of thermomechanical process with different cooling paths on microstructure and mechanical properties of low-carbon structural steel. Design/methodology/approach: The steel used for the investigation was subjected to two step deformation using a Gleeble 3800 simulator and then held at designed temperatures from 650ºC to 800ºC for different times. A final step included water cooling to room temperature to freeze the microstructure. Typical microscopic studies have been done. The analysis of the volume fraction of presented phases was carried out together with the measurement of grain size by means of image analysis. The last part of conducted research was hardness analysis of the steel after the different heat treatments. Findings: It was found that the microstructure constitution and grain size are strongly dependent on the temperature of isothermal holdings. The microstructure of steel held at 800ºC is composed of the mixture of bainite and two kinds of ferrite: globular and acicular. When the temperature was lowered by 50ºC the ferrite shows the globular morphology. When the temperature drops to 700ºC and below it, the microstructure is composed of ferritic-pearlitic mixture. It was observed that when the isothermal temperature was increased the grain size decreased and the opposite effect was observed for the holding time. The longer the time of the isothermal holding, the larger was the grain size. Research limitations/implications: For better understanding of the phase transformation kinetics in this steel the dilatometric test are planned. Practical implications: The knowledge of the microstructure evolution and hot deformation response of low-carbon structural steels is important from the industrial point of view. Originality/value: The combined effects of hot deformation and different cooling paths give the useful information on a microstructure evolution.

4

Structure and mechanical properties of newly-developed high-strength TRIPLEX type steels

Sozańska-Jędrasik L., Mazurkiewicz J., Borek W., Dobrzański L. A.

Inżynieria Materiałowa

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2018

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Vol. 39, nr 5

184--191

EN

The paper presents the results of mechanical properties research, fractographic investigations of fractures and microstructure of experimental high-strength high-manganese X98MnAlSiNbTi24–11 and X105MnAlSi24–11 TRIPLEX type steels. In order to determine the mechanical properties of the tested steels, microhardness tests and a static tensile test were performed, and yield stress, tensile strength and elongation of the tested steels were determined. The performed microstructure tests of the analysed steels using light microscopy allowed for the identification of austenitic-ferritic structure with the participation of carbides. It was found that the structure of both tested steels, which have undergone hot rolling followed by water cooling, consist of austenite grains with numerous annealing and deformation twins along with ferrite bands. The investigated steels are characterized by the mixed fractures of formed after a static tensile test after forging where there are areas of ductile fracture with small areas of transcrystalline and intergranular brittle fractures. The fractures after a static tensile test and after hot rolling and cooling in water have a dimple morphology characteristic of plastic fractures. The increase in hardness after thermomechanical treatment and after a static tensile test is caused by strain hardening affecting the achieved values of strength, yield point and hardness. The obtained research results allow to assess the impact of both the chemical composition and the applied thermomechanical treatment technology on the properties of newly developed steels.

PL

Celem pracy było określenie właściwości mechanicznych oraz plastycznych w powiązaniu z mikrostrukturą nowoopracowanych stali wysokomanganowych X98MnAlSiNbTi24–11 i X105MnAl- Si24–11 typu TRIPLEX po walcowaniu na gorąco w skali półprzemysłowej i chłodzeniu w wodzie. Uzyskane wyniki badań pozwolą na ocenę wpływu zarówno składu chemicznego, jak i zastosowanej technologii obróbki cieplno-mechanicznej na właściwości badanych stali.

5

Metalowo-szklane ściany osłonowe i przekrycia dachowe. Cz.1

Jakimowicz M., Borek W.

Builder

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2018

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R.22, nr 2

82--84, 86, 88, 90

EN

Metal-glass curtain wall s are now an inherent element of urban landscape. Due to the variety of forms, unlimited color range, high thermal and acoustic insulation, functionality dedicated not only to separating the external and internal environment they inspire admiration and delight. Their appearance can give the impression that they are uncomplicated structures. The reality is reversed. Metal-glass curtain walls are assembled from a number of functionally diverse elements. Designing the façade to meet the requirements is a complicated process where designers, architects, constructors and systems manufacturers must be involved. Very important is the stage of installation a metal-glass curtain wall. Without experienced assemblers and appropriate equipment, it is not possible to perform it correctly. For this in practice there are numerous defects arising at the design stage and at the montage stage.

6

Influence of Isothermal Heating Time on the Disappearance of Strain Hardening in High-Manganese TRIPLEX Type Steels

Sozańska-Jędrasik L., Mazurkiewicz J., Borek W.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 4

2023--2030

EN

The paper presents the results of the effect of isothermal heating time on the disappearance of strain hardening (the softening degree) of the studied high-manganese TRIPLEX type steels at a temperature of 900 and 1000°C. In order to determine the kinetics of recrystallization of austenite plastically deformed for selected steels, hot compression tests with draft ε = 0.2 were made. The presented results reveal that the complete recrystallization of austenite needs long isothermal heating times. In industrial conditions, such long times are not used, therefore in the initial rolling passages, the time required for half recrystallization of austenite t0.5 is often used. The total disappearance of the strain hardening, completion of the recrystallization of austenite tested high-manganese X98 and X105 TRIPLEX type steels isothermal heating time requires far more than 200 s. The increase of the deformation temperature is a factor influencing the acceleration of the disappearance of strain hardening.

7

Carbides Analysis of the High Strength and Low Density Fe-Mn-Al-Si Steel

Sozańska-Jędrasik L., Mazurkiewicz J., Borek W., Matus K.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 1

265--276

EN

The work presents the results of investigations into the structure and phase composition of newly developed high manganese steels of the X98MnAlSiNbTi24-11 and X105MnAlSi24-11 type. The average density of such steels is 6.67 g/cm3, which is 15% lower as compared to typical structural steels. An analysis of phase composition and structure allows to conclude that the investigated steels feature an austenitic γ-Fe(Mn,Al,C) structure with uniformly distributed and elongated α-Fe(Mn,Al) ferrite grains on the boundaries of austenite grains and carbides. Examinations by diffraction of back scattered electrons (EBSD) allow to conclude that high-angle boundaries dominate in such steels, having significant influence on mechanical properties. Three types of carbides with differentiated chemical composition and size were identified in steel X98MnAlSiNbTi24-11 with scanning and transmission electron microscopy. κ-(Fe,Mn)3AlC carbides, having a regular, face-centered cubic lattice (fcc), were identified in austenite. Transmission electron microscopy examinations have enabled to identify M7C3-type carbide in ferrite. Nb- and Ti-based complex carbides were identified in steel X98MnAlSiNbTi24-11, both, in ferrite and austenite. (NbTi)C2 carbide precipitates were confirmed in an X-ray qualitative phase analysis. The size of the above-mentioned carbides is within several to several dozens of μm. An X-ray qualitative phase analysis has confirmed the precipitates of M7C3 carbides in both steels.

8

Symulacja obróbki plastycznej materiałów inżynierskich z wykorzystaniem symulatora Gleeble 3800

Borek W.

LAB Laboratoria, Aparatura, Badania

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2017

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R. 22, nr 4

24--29

9

Structure and phase composition of newly developed high manganese X98MnAlSiNbTi24–11 steel of TRIPLEX type

Sozańska-Jędrasik L., Mazurkiewicz J., Borek W., Dobrzański L. A.

Inżynieria Materiałowa

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2017

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Vol. 38, nr 2

69--76

EN

The work presents the results of investigations of the structure and phase composition of newly developed high manganese X98MnAlSiNbTi24–11 steel of TRIPLEX type. The average density of such steel is 6.67 g/cm3, which is less than for typical structural steels by even 15%. A preliminary analysis of phase composition and structure allows to find an austenitic γ-Fe(Mn, Al, C) structure in the investigated steel with uniformly distributed ferritic α-Fe(Mn, Al) areas elongated towards the boundaries of austenite grains and numerous carbides with differentiated chemical composition and varied size. Nb- and Ti-based complex carbides are dominant in the steel. The investigations of the chemical composition of the carbides revealed in the matrix allow to identify with high probability dispersive κ-(Fe, Mn)3AlC carbides with the nanometric size of approx. 10÷160 nm, which has to be yet confirmed with electron transmission microscopy methods. Fe, Mn and Al as well as small amounts of Nb, Ti and Si are contained in such carbides. The occurrence of aluminium carbonitrides with a fraction of Nb and Ti was also revealed. The size of the above Nb and Ti carbides revealed in solid specimens in the matrix of the studied steel is between approx. 10 nm to 15 μm. X-ray diffraction examinations of carbide isolates prepared by the method of chemical dissolution in HCl showed the existence of NbTiC2 carbides in the studied steel. The diffraction examinations of solid specimens revealed, apart from austenite and ferrite, also the existence of TiC carbides and such initially classified as Mn3.6C0.4 type.

PL

Celem pracy była charakterystyka struktury i składu fazowego nowoopracowanej stali wysokomanganowej X98MnAlSiNbTi24–11 typu TRIPLEX zawierającej dodatki stopowe Ti i Nb przy dużej zawartości węgla.

10

Numerical analysis of the cavitation effect occurring on the surface of steel constructional elements

Linek T., Tański T., Borek W.

Archives of Materials Science and Engineering

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2017

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Vol. 85, nr 1

24--34

EN

Purpose: The aim of the work is to present the results of own investigations concerning the geometric optimisation of constructional elements working in the environment of cavitation wear together with a computer numerical analysis. The engineering material used for constructional elements working in the environment of cavitation wear is steel, commonly used for pressure devices working at elevated temperatures, P265GH, acc. to PN-EN 10028:2010. Design/methodology/approach: SOLID EDGE ST 7 software, for synchronous designing, was used for the parametrisation of the shape, distribution, configuration and size of openings in constructional elements. Five models, with a different spacing and number of openings, were proposed for the optimisation of internal geometry of the cavitation generator and for the investigations; the models were then subjected to a numerical analysis using specialised software, ANSYS FLUENT v.16, employed for modelling the effects associated with fluid mechanics (Computational Fluid Dynamics - CFD). The data was implemented for this purpose in the software used, such as: density, yield point, tensile strength, heat conductivity coefficient for steel P265GH, material surface roughness, medium (water) flow rate, constant pressure loss of medium, pressure of steam saturation in a medium; and such data was called boundary conditions. Findings: The authors’ principal accomplishment is the optimisation of the shape, the selection of the most appropriate geometry of a constructional element generating the maximum number of cavity implosions in the environment of a flowing medium (water), with the use of computer tools dedicated to engineering design: a 3D and numerical computer analysis of fluid mechanics, CFD. Moreover, an attempt was made in this work to develop a methodology for characterisation of the phenomena accompanying the environment of cavitation wear. Practical implications: A possibility of examining the phenomena and a process of wear of a constructional element made of P265GH grade steel for pressure devices working at elevated temperatures. The demonstration and presentation of potential places, areas and sizes of erosion existing on constructional elements working in the environment of cavitation wear.

11

Mechanical Properties of High-Mn Austenitic Steel Tested under Static and Dynamic Conditions

Dobrzański L. A., Borek W., Mazurkiewicz J.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 2A

725--730

EN

The purpose of the paper is to investigate X73MnSiAlNbTi25-1-3 high manganese austenitic steel containing 0.73% C to determine structural mechanisms decisive for increasing a reserve of cold deformation energy of such steel. The influence of a strain rate on the structure of the investigated steels and on the structural mechanisms decisive for their properties was analysed. Specialist research instrumentation was used for this purpose such as Scanning Transmission Microscopy (including EBSD examinations), conventional and high-resolution transmission electron microscopy together with diffraction examinations and metallographic examinations. It was found that the principal cause of an increased reserve of cold deformation energy of the investigated steels in dynamic conditions is the activation of mechanical twinning in the mutually intersecting systems in austenite grains and annealing twins, which are densifying when a cold deformation rate is growing, thereby confirming the basic mechanism of TWIP (TWinning Induced Plasticity).

12

Effect of Laser Feeding on Heat Treated Aluminium Alloy Surface Properties

Labisz K., Tański T., Janicki D., Borek W., Lukaszkowicz K., Dobrzański L. A.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 2A

741--746

EN

In this paper are presented the investigation results concerning microstructure as well as mechanical properties of the surface layer of cast aluminium-silicon-copper alloy after heat treatment alloyed and/ or remelted with SiC ceramic powder using High Power Diode Laser (HPDL). For investigation of the achieved structure following methods were used: light and scanning electron microscopy with EDS microanalysis as well as mechanical properties using Rockwell hardness tester were measured. By mind of scanning electron microscopy, using secondary electron detection was it possible to determine the distribution of ceramic SiC powder phase occurred in the alloy after laser treatment. After the laser surface treatment carried out on the previously heat treated aluminium alloys, in the structure are observed changes concerning the distribution and morphology of the alloy phases as well as the added ceramic powder, these features influence the hardness of the obtained layers. In the structure, there were discovered three zones: the remelting zone (RZ) the heat influence zone (HAZ) and transition zone, with different structure and properties. In this paper also the laser treatment conditions: the laser power and ceramic powder feed rate were investigated. The surface laser structure changes in a manner, that there zones are revealed in the form of. This carried out investigations make it possible to develop, interesting technology, which could be very attractive for different branches of industry.

13

Structure and properties of AlMg alloy after combination of ECAP and post-ECAP ageing

Tański T., Snopiński P., Pakieła W., Borek W., Prusik K., Rusz S.

Archives of Civil and Mechanical Engineering

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2016

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Vol. 16, no. 3

325--334

EN

Equal channel angular pressing technique (ECAP) was used before and after solution heat treatment to obtain grain refinement and strengthening of commercial Al–Mg casting alloys. The experiments were performed to investigate the strengthening effect of the alloy after various post-ECAP ageing treatments. The alloys were severely deformed at room temperature following route Bc and die channel angle of 120°. It was found that heat treatment before and after ECAP significantly affect and improves mechanical properties of aluminium alloys. It was also proven that the severe plastic deformation causes grain refinement which directly influence on properties of AlMg alloys. An increase of strength and ductility was achieved by appropriate selection of post-ECAP ageing. It is also proven that the good strengthening effect is also achieved at temperatures lower than those usually used for ageing. Based on the findings above, the tensile properties and hardness of Al–Mg alloys are discussed.

14

Możliwości symulatora obróbki cieplno-plastycznej

Borek W.

Stal, Metale & Nowe Technologie

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2015

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nr 9-10

82--84

PL

Dążenie do optymalizacji procesów technologicznych i produkcyjnych, jak również dobór najlepszego pod względem ekonomicznym materiału konstrukcyjnego pociąga za sobą konieczność zintensyfikowania badań w zakresie fizycznych symulacji procesów obróbki cieplnej i cieplno-plastycznej nowych materiałów inżynierskich. Osiągnięcie wszystkich kryteriów wiąże się z dostępem do najnowocześniejszych rozwiązań technologicznych, które pozwalają na wykonanie symulacji fizycznych procesów takich jak: ciągłe odlewanie, walcowanie, ściskanie, ciągnienie, kucie, wyciskanie, zgrzewanie i operacje obróbki cieplnej.

EN

The need for the optimization of technological processes and production, as well as the best selection of structural material in terms of economic considerations entails the necessity to extend research on the physical simulation of heat treatment and thermo-mechanical treatment of new engineering materials. Achieving all the criteria is associated with the availability of modern technology solutions, which allow to perform the simulations of physical processes such as: continuous casting, rolling, pressing, drawing, forging, extrusion, welding and heat treatment operations.

15

TWIP mechanism in processing of high-manganese austenitic steel

Dobrzański L. A., Borek W., Mazurkiewicz J.

Journal of Achievements in Materials and Manufacturing Engineering

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2015

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Vol. 71, nr 1

22--27

EN

Purpose: The aim of this paper is to determine the high-manganese austenite propensity to twinning induced by the cold working and its effect on structure and mechanical properties, and especially the strain energy per unit volume of new developed high-manganese Fe-Mn-(Al,Si) high-manganese austenitic TWIP (TWinning Induced Plasticity) steel containing about 25% Mn, 1% Si, 3% Al. Design/methodology/approach: The essence of the research concerns the analysis of the influence of microstructure evolution during cold plastic deformation. The microstructure of investigated steel was determined in metallographic investigations using light, scanning and high- resolution transmission electron microscopies (HRTEM). Findings: The activation of intensive mechanical twinning mechanisms in high-manganese austenitic steels, in order to increase strain energy, allows the formation of technological components of complex shape or permits the discharge of energy during cold plastic deformation. According to currently presented views, it is believed that the new austenitic steels with the A1 crystallographic structure containing Mn more than 25 mass.%, Si and Al can provide a significant advance, particularly in automotive applications, because practically there are no more possibilities to improve at the same time the strength and ductility of the steel with A2 crystallographic structure. Research limitations/implications: Results obtained in static conditions for new developed high-manganese austenitic steel indicate the possibility and purposefulness of their employment for constructional elements of vehicles, especially of the passenger cars to take advantage of the significant growth of their strain energy per unit volume which guarantee reserve of plasticity in the zones of controlled energy absorption during possible collision resulting from activation of twinning induced by cold working, which may lead to significant growth of the passive safety of these vehicles' passengers. Originality/value: TWIP steels show not only excellent strength, but also have excellent formability due to twinning, thereby leading to an excellent combination of strength, ductility, and formability over conventional dual-phase steels.

16

Obróbka cieplno-plastyczna stali austenitycznej wysokomanganowej z wykorzystaniem symulatora Gleeble 3800

Borek W.

Stal, Metale & Nowe Technologie

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2014

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nr 1-2

38--40

PL

Rozwój branży automotive skłania inżynierów do opracowywania nowatorskich materiałów konstrukcyjnych, o coraz lepszych własnościach wytrzymałościowych, przy zachowaniu wymaganej podatności na kształtowanie, a w szczególności na głębokie tłoczenie. Połączenie własności wytrzymałościowych i plastycznych stali ma szczególnie korzystne znaczenie nie tylko w procesie wytwórczym stali i elementów konstrukcyjnych samochodów, ale również w trakcie ewentualnego wypadku podczas użytkowania samochodu, ze względu na duży zapas plastyczności w strefach kontrolowanego pochłaniania energii uszkodzonego pojazdu.

17

Utilization of acoustic emission at study of mechanical properties and structure of magnesium-aluminium alloy AZ61 under elevated temperatures

Cizek L., Hanus A., Lichy P., Tański T., Kraus M., Rusz S., Borek W.

Archives of Materials Science and Engineering

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2014

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Vol. 68, nr 2

66--74

EN

Purpose: This work present experimental determination of the elastic-plastic condition of the magnesium alloy depending on the temperature and pace of the sample tensile stress. Design/methodology/approach: At the acoustic emission (next denoted the „AE”) use, tensile tests at high temperatures may, among other things, be used for analysis of the AE signal sources and set, in more detail, the temperature limit of elastic-plastic deformations existence in the material under examination. The AE is, during tensile tests at high temperatures, based on the scanning of released elastic waves generated by sharp tension changes in the body as a result of the subsequent physical-metallurgical processes such as plastic deformation, tension redistributing, creation of microcracks and their spreading in macroscopic scale. Findings: The aim of the acoustic emission monitoring at tensile tests at higher temperatures is therefore the specification of the critical heat barrier of the elastic-plastic condition of materials and provision of information concerning the dynamics of deformation processes at tension including influences of surface layers for which acoustic emission, as confirmed by measurement results is a very suitable method. Research limitations/implications: The results of testing above mentioned magnesium alloys will serve for evaluation of possibility those magnesium alloys for application of SPD methods. Presented work was further focused on determination of structure characteristics including investigation of fracture characteristics with use of light microscopy and SEM analysis. Originality/value: Knowledge of the relaxation properties of metal materials at high temperatures is necessary for the verification of susceptibility of castings to the creation of defects during the production process. Generated tensions in the castings are the cause of creation and development of defects.

18

Influence of thermo-plastic deformation on grain size of high-manganese austenitic X11MnSiAl17-3-1 steel

Dobrzański L.A., Czaja M., Borek W., Labisz K.

Journal of Achievements in Materials and Manufacturing Engineering

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2013

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Vol. 61, nr 2

169--174

EN

Purpose: The aim of the paper is to compare fragmentation of grains after thermo-mechanical treatment using Gleeble 3800 simulator of high-manganese austenitic X11MnSiAl7-1-3 steel. Design/methodology/approach: The hot-working behaviour was determined 4- and 8-stage compression tests performed in a temperature range of 850 to 1100°C by the use of the Gleeble 3800 thermo-mechanical simulator. The comparison between two type of thermo-mechanical treatment has been established based on microstructure research and X-ray diffraction analysis. Findings: It was found that steel X11MnSiAl7-1-3 in initial state and after thermo-mechanical treatment on Gleeble simulator has homogeneous austenite structure. Compression tests were realized in the temperature range from 850 to 1050°C with the true strain 4x0.23 for 4-stage process, and 0.4 in the first deformation, and 0.25 and 0.2 in the following deformations for 8-stage process. The multi-stage compression examination gives the possibility to refine the austenite microstructure. Based on microstructures research were found that this process perfectly led to fragmentation of the material structure which may result in the ideal material properties. Practical implications: The obtained microstructure after Gleeble simulations can be useful in determination of power-force parameters of hot-rolling for thin sheets to obtain fine-grained austenitic microstructures. Originality/value: The hot-working behaviour and microstructure evolution in various conditions of plastic deformation for new-developed high-manganese austenitic steels were investigated.

19

Structure of X11MnSiAl17-1-3 steel after hot-rolling and Gleeble simulations

Dobrzański L., Borek W., Czaja M., Mazurkiewicz J.

Archives of Materials Science and Engineering

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2013

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Vol. 61, nr 1

13--21

EN

Purpose: The aim of the paper is to compare results after thermo-mechanical simulation using Gleeble 3800 and hot-rolling on LPS module of high-manganese austenitic X11MnSiAl7-1-3 steel. Design/methodology/approach: The hot-working behaviour was determined in continuous, 4- and 8-stage compression tests performed in a temperature range of 850 to 1100°C by the use of the Gleeble 3800 thermo-mechanical simulator and LPS module for semi-industrial hot rolling. The comparison between two processes has been established based on microstructure research and X-ray diffraction analysis. Findings: It was found that austenite microstructure with numerous annealing twins in the initial state was obtained. 4-stage compression tests were realized in the temperature range from 850 to 1050°C with the true strain 4x0.23. 8-stage compression test were performed in the same temperature range and with true strain of 0.4 in the first deformation, and 0.25 and 0.2 in the following deformations. The multi-stage compression examination gives the possibility to refine the austenite microstructure. Based on this research hot-rolling on LPS module in the temperature range from 1100°C to 850°C was realized. Based on microstructures research were found that this process is not perfect due to longer intervals between successive passes and inability to control the temperatures of following passes. Practical implications: The obtained stress-strain curves relationship and microstructure after Gleeble simulations can be useful in determination of power-force parameters of hot-rolling for thin sheets to obtain fine-grained austenitic microstructures. Originality/value: The hot-working behavior and microstructure evolution in various conditions of plastic deformation for new-developed high-manganese austenitic steels were investigated.

20

Microstructure evolution after thermo-mechanical treatment of X11MnSiAl25-1-3 TWIP-type steel

Dobrzańska-Danikiewicz A., Borek W., Mazurkiewicz J., Jagiełło A.

Archives of Materials Science and Engineering

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2013

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Vol. 59, nr 1

14--21

EN

Purpose: The purpose of the article is to present the results of research of the effect of thermal and thermoplastic working on the structure of high-manganese austenitic TWIP steels. Design/methodology/approach: Plastometric tests were performed with DSI (Dynamic System Inc.) Gleeble 3800 instrumentation being the equipment of the Scientific and Didactic Laboratory of Nanotechnology and Materials Technologies of the Institute of Engineering Materials and Biomaterials. Changes in the microstructure after individual stages of hot plastic deformation were determined on the basis of detailed microstructure tests with the light microscope and scanning electron microscope. An X-ray phase qualitative analysis of the examined materials in the condition after casting and after thermoplastic working was carried out with the XPert diffractometer by Philips. Findings: It was concluded based on the tests performed that the structure of the examined austenitic high-manganese steel in the initial condition is represented by austenite with numerous annealing twins. The results obtained for investigations in a continuous compression test will enable to establish power and energy parameters and design a hot compression process, consisting of several phases, of axisymmetric specimens, simulating the final rolling passes. Practical implications: By elaborating the detailed data concerning structural changes and power and energy parameters of the thermoplastic working process of the investigated high-manganese austenitic TWIP steel type, it will be possible to design appropriately the final passes of the hot rolling process to obtain an optimum size of grains, which will in turn influence the improved strength properties of the investigated high-manganese austenitic X11MnSiAl25-1-3 steel. Originality/value: The application of thermoplastic working of high-manganese austenitic TWIP steel.