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| Abstract No.: |
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Scheduled at:
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Tuesday, May 21, 2019, Saal Brüssel 11:40 AM
Brazing for tool applications
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| Title: |
The effect of nickel-plated surfaces on the microstructure and the strength of vacuum brazed nickel maraging steel
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| Authors: |
Tim Henning* / Dortmund University of Technology, Germany
Wolfgang Tillmann / Technische Universität Dortmund, DE
Lukas Wojarski/ Technische Universität Dortmund, DE
M. Möbus/ Technische Universität Dortmund, DE
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| Abstract: |
Nickel maraging steels are high-alloy and precipitation hardenable tool steels with excellent strength, hardness and toughness properties. These steel grades are primarily used for tools exposed to high stresses, such as hydraulic chucks or injection molds, with an integrated complex channel structure to pressurize or cool the tool. Within this context, vacuum brazing of segmented parts is a promising manufacturing process that offers the advantage of combining the heat treatment of the base material with the joining process. Although it is known that nickel-plated surfaces ensure the wettability and improve the strength of such joints, a basic metallurgic understanding of these effects is yet still missing. Thus, this research focus on the investigation of miscellaneous silver-based brazing alloys for non-plated and nickel-plated surfaces of material grade AISI 18MAR300 (1.2709). It is shown that the improved joint strength of nickel-plated samples is related to the formation of Ag(Cu) and CuNi phases instead of eutectic and Cu(Ag) phases as for non-plated surfaces. In case of the plated samples, the joint strength increased with a reduced presence of Ag(Cu) phases. In addition, palladium was identified as a key element to strengthen up this phase by the formation of Ag(Cu,Pd) solid solution, which enable to obtain a maximum tensile strength of 654 MPa by using AgCu27Pd5 as brazing alloy.
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