Abstract
This study was carried out to investigate the relationship between the thickness of the oxide film on a faying surface and the tensile strength of the titanium joints brazed in argon atmosphere using Ag-based filler metal, and to examine the behavior of the oxide film during the brazing process. The following results were obtained in this study.
The specimen with a Paying surface oxidized at temperatures lower than 600°C can be easily brazed in argon atmosphere, and the joints brazed at 800°C possess the tensile strength of approximately 300 MPa. The thickness of an oxide film decreases during heating to the brazing temperature. For instance, heating to the brazing temperature of 800°C turns the oxide film of about 71 nm in thickness formed at 600°C into about 23 nm thickness.
Copper in a molten filler metal predominantly diffuses through the thin oxide film and is enriched at the surface of titanium, and results in reacting to titanium.
Microcracks existing in the oxide film grow larger with heating to the brazing temperature. It seems that a molten filler metal penetrates into the cracks and results in benefitting the joining process.
