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

Franczak Krystian, Kwaśniewski Paweł, Kiesiewicz Grzegorz, Zasadzińska Małgorzata, Jurkiewicz Bartosz, Strzępek Paweł, Rdzawski Zbigniew

Archives of Civil and Mechanical Engineering

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2020

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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.

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

Jurkiewicz Bartosz, Smyrak Beata, Zasadzinska Malgorzata, Franczak Krystian, Strzepek Pawel

Archives of Civil and Mechanical Engineering

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2019

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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.

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

Zasadzińska Małgorzata, Knych Tadeusz, Strzępek Paweł, Jurkiewicz Bartosz, Franczak Krystian

Archives of Civil and Mechanical Engineering

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2019

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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.