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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.

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Structure of the copper under controlled deformation path conditions

Niewielski G., Kuc D.

Archives of Materials Science and Engineering

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2009

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Vol. 35, nr 1

5-12

EN

Purpose: One of the methods of plastic deformation under complex deformation path conditions is compression with oscillatory torsion. The observable effects in the form of changing force parameters and structure changes confirm the possibility of deformation to a value many times higher than in the case of methods traditionally applied for forming. This article presents the results of the influence of compression with oscillatory torsion on structural phenomena occurring in copper deformed in such a way. Design/methodology/approach: The examinations were conducted at a compression/oscillatory torsion test stand. The structural examinations were conducted with the use of light and electron microscopy. Findings: In experimental investigations, a reduction of unit pressures was observed when compared to conventional compression. The structural examinations indicated substantial differences in the mechanisms of plastic deformation conducted in both conventional and combined way. Research limitations/implications: There are premises which show that a metallic material of a nanometric structure can be obtained in this way (top-down method), by the accumulation of great plastic deformation. Metallic materials characterized by grain size below 100nm are distinguished by unconventional properties. Further examinations should focus on conducting experiments in a way that would enable grain size reduction to a nanometric size. This will enable the cumulation of greater deformation in the material. Originality/value: The method of compression with oscillatory torsion is an original method developed at the Silesian University of Technology, owing to which it is possible to obtain high deformation values (SPD) without risking the loss of cohesion of the material. Thorough understanding of the changes taking place in the structure of metals subjected to compression with oscillatory torsion will allow the optimal choice of process parameters in order to achieve a gradual grain size reduction.

3

Structure of the copper under controlled deformation path conditions

Niewielski G., Kuc D.

Archives of Materials Science and Engineering

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2009

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Vol. 36, nr 1

20-27

EN

Purpose: One of the methods of plastic deformation under complex deformation path conditions is compression with oscillatory torsion. The observable effects in the form of changing force parameters and structure changes confirm the possibility of deformation to a value many times higher than in the case of methods traditionally applied for forming. This article presents the results of the influence of compression with oscillatory torsion on structural phenomena occurring in copper deformed in such a way. Design/methodology/approach: The examinations were conducted at a compression/oscillatory torsion test stand. The structural examinations were conducted with the use of light and electron microscopy. Findings: In experimental investigations, a reduction of unit pressures was observed when compared to conventional compression. The structural examinations indicated substantial differences in the mechanisms of plastic deformation conducted in both conventional and combined way. Research limitations/implications: There are premises which show that a metallic material of a nanometric structure can be obtained in this way (top-down method), by the accumulation of great plastic deformation. Metallic materials characterized by grain size below 100nm are distinguished by unconventional properties. Further examinations should focus on conducting experiments in a way that would enable grain size reduction to a nanometric size. This will enable the cumulation of greater deformation in the material. Originality/value: The method of compression with oscillatory torsion is an original method developed at the Silesian University of Technology, owing to which it is possible to obtain high deformation values (SPD) without risking the loss of cohesion of the material. Thorough understanding of the changes taking place in the structure of metals subjected to compression with oscillatory torsion will allow the optimal choice of process parameters in order to achieve a gradual grain size reduction.

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The impact of compression with oscillatory torsion on the structure change in copper

Wrożyna A., Niewielski G., Rodak K., Kuc D., Grosman F., Pawlicki J.

Archives of Civil and Mechanical Engineering

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2007

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Vol. 7, no 2

39-46

EN

The influence of compression with oscillatory torsion on the copper structure and force parameters are presented. The compression with oscillatory torsion method, developed in the Faculty of Materials Science and Metallurgy at the Silesian University of Technology, is used to achieve severe plastic deformation resulting in homogeneous ultrafine-grained structure of metals. The deformation resistance of copper for various torsion frequency and compression rate is presented. The results of microstructural observations by using LM (Iight microscope) and TEM (Transmission Electron Microscope) technique are displayed as well. The geometrical parameters of structure elements and their misorientation angles were characterized by using TEM method. Application of compression with oscillatory torsion was found to cause a remarkable decrease of deformation resistance as compared to compression without torsion. Plastic flow localized in shear bands was observed. Structures with large misorientation occur in microbands areas. The banded structure formed during compression with oscillatory torsion consists of well-formed, elongated subgrains.

PL

W pracy przedstawiono wpływ ściskania z oscylacyjnym skręcaniem na mikrostrukturę miedzi i zmiany parametrów siłowych procesu odkształcania. Metodą ściskania z oscylacyjnym skręcaniem, nad którą trwają prace na Wydziale Inżynierii Materiałowej i Metalurgii Politechniki Śląskiej, realizuje się duże odkształcenia plastyczne w celu uzyskania jednorodnej struktury ultradrobnoziarnistej. W pracy opisano wpływ parametrów procesu na przebieg średnich nacisków jednostkowych oraz strukturę miedzi obserwowanej metodami mikroskopii świetlnej i transmisyjnej mikroskopii elektronowej. Określono cechy geometryczne elementów substruktury oraz ich wzajemną dezorientację. Stwierdzono, że zastosowanie metody niekonwencjonalnego odkształcania spowodowało spadek średnich nacisków jednostkowych w porównaniu z parametrami odkształcenia konwencjonalnego. Obserwowano lokalizację płynięcia plastycznego w pasmach ścinania. W obszarach mikropasm ścinania powstała struktura o dużym stopniu wzajemnej dezorientacji. Ponadto stwierdzono, że struktura pasmowa tworząca się w procesie niekonwencjonalnego odkształcenia złożona jest z dobrze ukształtowanych i wydłużonych podziarn.