Wyniki wyszukiwania - Biblioteka Nauki

1

The researches of influence of strengthening on fatigue strength of aluminium wires for OHL conductors

100%

Jurkiewicz B. , Smyrak B. , Zasadzinska M. , Franczak K. , Strzepek P.

Archives of Civil and Mechanical Engineering

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2019

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tom Vol. 19, no. 3

862--870

EN

The traditional overhead conductors (OHL conductors) are made from a high strength steel core and several layers of aluminium wires. Operating conditions under variable stress derived from von Karman vortices leads to fatigue cracking of the outer layer of wires, first of the outer layer, and then the inner layers. The dynamic component of tension, dependent on the static tension of the wire, its geometric construction and rigidity (the number and diameter of the wires, the coil angle), lead to fatigue destruction of the wires. The conse-quence of this is the gradual degradation of the conductor as a whole, which is a decrease in the electrically active cross-section, and as a result of overheating, also in its mechanical properties. The ultimate effect is breaking of the conductor and a fault of the power line. The subject of the paper concerns fatigue strength tests of cold-drawn commercially pure aluminium wires in different temper of strain hardening. The paper attempts to describe fatigue strength, research methodology, description of a research stand. Based on study results and their analysis, conclusions were formulated concerning the differentiation of fatigue strength and EN AW-1370 wires used for overhead power conductors.

2

Analysis of the strengthening and recrystallization of electrolytic copper (Cu-ETP) and oxygen free copper (Cu-OF)

100%

Zasadzińska M. , Knych T. , Strzępek P. , Jurkiewicz B. , Franczak K.

Archives of Civil and Mechanical Engineering

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2019

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tom Vol. 19, no. 1

186--193

EN

The research paper studies the strengthening and the kinetics of recrystallization of ETP copper and OF copper. This research covers a wide scope of strain hardening specific for the manufacturing of microwires (true strain of the order of 5) and the range of temperatures and times of the recrystallization process referring to the real life conditions occurring in advanced technologies of microwires’ manufacturing. As a result of the performed tests, it was established that the recrystallization temperature of ETP copper is lower than the recrystallization temperature of OF copper regardless of the recrystallization time as the recrystallisation effect can be achieved after about 10–30 s regardless of the copper grade.

3

Research of mechanical and electrical properties of Cu–Sc and Cu–Zr alloys

86%

Franczak K. , Kwaśniewski P. , Kiesiewicz G. , Zasadzińska M. , Jurkiewicz B. , Strzępek P. , Rdzawski Z.

Archives of Civil and Mechanical Engineering

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2020

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tom Vol. 20, no. 1

390--404

EN

The research paper presents the impact of the scandium additive and various conditions of the heat treatment on copper mechanical, electrical and heat resistance properties. The performed research works included manufacturing of CuSc0.15 and CuSc0.3 alloys through metallurgical synthesis with the use of induction furnace and following crystallization in graphite crucibles at ambient temperature. Additionally, a CuZr0.15 alloy was produced as a reference material for previously syn-thesized Cu–Sc alloys. During research, the selection of heat treatment for the produced materials was conducted in order to obtain the highest mechanical–electrical properties ratio. Materials obtained in such a way were next subjected to thermal resistance tests. Parameters of thermal resistance test included temperatures from the range of 200–700 °C and 1 h of anneal-ing time. The research has shown that CuSc0.15 and CuSc0.3 alloys have higher heat resistance after their precipitation hardening compared to the Cu–Zr alloy. The paper also presents microstructural research of the produced materials, which showed that alloying elements precipitates are mainly localized at the grain boundaries of the material structure.

4

Research on Changes in Microstructures and Mechanical Properties of Welding Caps as a Result of their Usage During Resistance Spot Welding Process

86%

Rdzawski Z. , Kwaśniewski P. , Głuchowski W. , Łagoda M. , Maleta M. , Boczkal S. , Franczak K.

Archives of Metallurgy and Materials

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2023

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tom Vol. 68, iss. 1

295--306

EN

Mating electrodes made of copper alloys are commonly used for welding galvanized steel sheets used in the production of car bodies. These alloys are characterized by high mechanical properties, a high level of electrical and thermal conductivity as well as the stability of these properties under changing conditions of current, thermal and mechanical load. Much careful attention was paid to the essence of the ongoing structural changes as well as to the mechanical properties in the welding process (RSW - Resistant Spot Welding) of steel sheets, including high-strength ones. There is a lack of research on structural changes and the related mechanical properties occurring in welding electrodes made of copper alloys caused by the welding process. This study is devoted to these issues and contains a critical review of the research results enabling a better understanding of the relationships between the structure and properties of welding electrodes caused by the cyclic welding process. In order to illustrate the phenomena occurring during the welding process, both in the material to be welded and in the tip electrodes, hardness and structural tests were carried out on electrode samples before and after their exploitation. The data collected in the article supplements a certain lack of information in the literature regarding the microstructural aspects of the welding process of galvanized steel sheets for the production of car bodies. The conducted research may be the starting point for the search for more effective materials for the tip electrodes.

5

Studies on the influence of AlTi5B1 modifier on the structure and properties of AlCuMg alloys

86%

Ściężor W. , Kowal R. , Franczak K. , Grzebinoga J. , Kwaśniewski P. , Kiesiewicz G.

Acta Innovations

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2021

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tom no. 38

37--48

EN

New materials used in various industries require sufficiently high mechanical properties, fine-grained structure and ease of metal forming while minimizing production costs. For this reason, work is being carried out to develop new groups of alloys that make it possible to increase the strength of the obtained components while reducing their weight, and thus reducing production costs. This article focuses on two aluminium-based alloys with different content of alloying additives: copper and magnesium i.e., AlCu3Mg3 and AlCu4.5Mg6, which were produced by metallurgical synthesis. The as-cast alloys were characterized for their basic physical, mechanical and electrical properties and were subjected to structural analysis. In the next stage, the alloys were modified with 100, 500, 1000 and 2000 ppm of titanium and then their hardness, electrical conductivity and density were tested. Samples were also subjected to microstructural analysis. The obtained results allowed to examine the evolution of the AlCuMg alloy properties depending on the content of alloy additives and the amount of used modifier.