Titanium Braze System for High Temperature Applications.
Final technical rept. 7 May 74-30 Apr 76,
SOLAR SAN DIEGO CALIF
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This report describes the design rationale and development of special, high-temperature braze systems for joining titanium and titanium alloys, suitable for long term aerospace application to 800 F. Candidate braze alloy designs were substrate-compatible, low-melting 1650-1750 F compositions within the metallurgically similar Ti, Zr-, Ti-Zr, Ti-V, and Zr-V-Ti base systems. Best results were obtained with the Ti-Zr system. Desired hypoeutectic structure and melt-solidification behavior were achieved wherever possible through controlled reduction of major melting-point depressants andor ZrTi ratios, backing-off from eutectic alloying levels. Principal alloying objectives were a braze strength, toughness and ductilTy properties RT-800 F comparable to the high-melting TI-15Cu-15Ni baseline braze alloy, b conventional brazing characteristics superior to the baseline braze, particularly brazing capability or 1750 F to avoid beta embrittlement of the substrate Ti-6Al-4V and c intrinsic long-term resistance to structural damage from aqueous salt spray, 800 F air oxidation, and 800 F hot-salt corrosion. Over 350 different braze alloy designs were evaluated through various screening tests. The two braze alloy designs which best met program objectives are designated AC5-16 Ti-27.2Zr-15.ONi-7.OCu and AC1-20 Ti-28.8Zr-28.OCu. The principal substrate alloy employed was Ti-6Al-4V some comparison tests were conducted wITh Beta-C substrate alloy.
- Properties of Metals and Alloys
- Fabrication Metallurgy