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5994 |
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Tuesday, May 21, 2019, Saal Brüssel 12:20 PM Brazing for tool applications |
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Fundamental study on tempered state of steel influenced by the brazing process parameters for joining of hard metal saw teeth to steel saw blades |
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Gunther Wiehl* / Saxonia Technical Materials GmbH, Germany Max Schimpfermann / Saxonia Technical Materials GmbH, Germany Sven Rassbach/ CERATIZIT Luxembourg S.à r.l., Luxembourg Michael Magin/ CERATIZIT Luxembourg S.à r.l., Luxembourg Adam Kazuch/ Risse + Wilke Kaltband GmbH & Co. KG, Germany Maurizio Marchi/ Risse + Wilke Kaltband GmbH & Co. KG, Germany Norbert Unnasch/ Risse + Wilke Kaltband GmbH & Co. KG, Germany |
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The production of high-strength brazing joints between hard metal saw teeth and steel blades for circular saws poses a demanding technical challenge for the brazing operation itself and the components involved (hard metal teeth, silver brazing alloy and steel blades). The automated industrial brazing operation is typically conducted by using induction heating and a fluxing agent in air. An important technical requirement is that the brazing heat does not modify the local steel microstructure close to the brazing gap because mechanical properties of the final saw blade are sensitively dependent on the precisely adjusted steel microstructure. Therefore, typically low-melting silver brazing alloys with recommended brazing temperatures between 690-720°C are used in the tooling industry. The present scientific study elaborates how brazing process parameters such as brazing temperature and time influence the local steel microstructure and thus the local micro hardness profile of different steel grades close to the brazing gap. For the brazing operation a new silver reduced brazing alloy with the composition of CuAg28Zn20Mn10In2Ni1 and the standardized silver alloy Ag 449 according to DIN EN ISO 17672 were used. The investigations were conducted in the brazing temperature range up to 850°C with different grades of steel typically used for saw blades. The results are discussed in the framework of the technical abilities and challenges of a typical industrial production process. |