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| Abstract No.: |
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Scheduled at:
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Thursday, May 23, 2019, Saal Brüssel 1:40 PM
Brazing of Ni-/Fe-based materials
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| Title: |
Effect of brazing atmosphere on the corrosion resistance of ferritic stainless steels brazed with Ni- and Fe-base filler metals
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| Authors: |
Torstein Grøstad / Höganäs AB, Sweden
Martin Stroiczek* / Höganäs GmbH, Germany
Lisa Kjellén/ Höganäs AB, Sweden
T. Grostad/ Höganäs AB, Sweden
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| Abstract: |
Ferritic stainless steels are gaining interest due to the combination of low cost, low thermal expansion and good high temperature scaling resistance compared to the commonly used austenitic stainless steels. These materials are of special interest for exhaust gas system components in gasoline cars, where the service temperatures are higher than for diesel cars. Previous research on the corrosion resistance of brazed ferritic stainless steel components have focused solely on vacuum brazed components, while the focus on belt furnace brazing has been limited. The presence of nitrogen in the brazing atmosphere has been found to affect the corrosion resistance of the base materials and filler materials in studies with austenitic stainless steels, but the effect on ferritic stainless steels has not yet been studied. In this investigation, AISI 430 and AISI 441 test samples were brazed with the common Ni-base brazing filler metals BNi-2, BNi-7, Ni613 and Höganäs iron-base brazing filler metals BrazeLet® F300 and BrazeLet® F86. Specimens were brazed in three different conditions: Vacuum furnace brazing, 90N2/10H2 belt furnace brazing and 100H2 belt furnace brazing. The effect of the brazing atmosphere on corrosion resistance was evaluated by VDA 230-214 K.2.2 testing and SS-EN ISO 16701 salt spray testing. Significant differences in corrosion resistance were observed for the tested brazing filler metals, with BNi-2 experiencing the most severe corrosion attack. The brazing atmospheres were found to affect the brazed joint and base material corrosion resistance. Moreover, the differences in the brazing cycle time between belt furnace brazing and vacuum furnace brazing lead to significant differences in the grain growth of the base materials.
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