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7199 |
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Tuesday, June 21, 2022, Saal Brüssel 4:40 PM Properties of brazed joints |
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Effect of morphic difference between foil and powder on brazed area corrosion resistance |
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Koki Yamazaki* / Tokai University, Japan Yasuyuki Miyazawa / Tokai-University, Japan Hyougo Kato/ Tokai-University, Japan Yoshio Bizen/ Hitachi Metals, Ltd., Japan |
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In this laboratory, the brazing of stainless steels with foil-type Ni brazing filler metal has been vigorously studied. As a result, it was confirmed that the reaction between boron (B) in the brazing filler metal and chromium (Cr) in the base metal results in the formation of Cr-B compounds, which are reticulate in austenitic stainless steels and needle-like in ferritic stainless steels. It has been confirmed that the effect of this reaction causes a Cr-deficient layer near the interface of the brazed joint, which adversely affects the corrosion resistance of the entire brazed joint. There is a few research on the differences in microstructure and corrosion resistance that occur in brazed joint due to differences in the morphology of foil and powder. It is important to clarify whether there is any difference between the two forms, since powder is now being replaced by foil. In this study, the corrosion resistance of Ni-based foil brazing filler metal and that of powder type brazing filler metal were evaluated by combining electrochemical corrosion resistance evaluation and microstructural observation using EPMA, and the results were compared with previous results. |