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6017 |
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Tuesday, May 21, 2019, Saal Brüssel 12:00 PM Brazing for tool applications |
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Brazing of cemented carbide and steel with Cu-Mn-Ni filler metals |
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Igor Pashkov* / PBSU, Russia T. Bazlova, / MISIS, RU V. Bazhenov/ MISIS, RU V. Misnikov/ PBSU, RU |
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Cu-Mn-Ni system filler metals are widely used for brazing carbide tools in various fields of engineering. Brazed joints obtained with filler metals of this group have increased strength to alternating loads and, as a rule, are used in the mining industry. The work compares brazed joints obtained with Cu-Mn-Ni filler metals with different content of manganese and nickel in order to establish the relationship between the morphology of the microstructure of brazed joints and their chemical composition. Electron microscopy was used to study the behavior of joints during crystallization in a wide and narrow gap. Depending on the brazing temperature and the iron content, the dissolution of steel and the crystallization of phases based on iron are considered. The regularities of crystallization are revealed depending on the content of nickel and manganese. The phenomenon of anomalous diffusion activity of cobalt is observed during prolonged exposure at the brazing temperature, which leads to the isolation of the cobalt rich phase at the solid-steel alloy boundary. In this case, the cobalt phase is separated from the cemented carbide by an interlayer of iron. Work materials can be useful for adjusting the technological modes of brazing of mining and cutting tools, to increase mechanical strength and reduce the porosity of brazed joints. |