R. A. G. Gourley, I. Wilson, Curtiss Wright, Cheswick, PA; D. Pratt, ex-Bechtel Plant Machinery, Inc., Pittsburgh, PA; J. Lewis, Wall Colmonoy Corporation - retired, Dayton, OH

Summary: A development program to select a braze alloy to vacuum braze shrouds to open face centrifugal pump impellers was designed and completed. This program considered two different braze alloys, BNi-5 and BAu-4, which were brazed to cast, martensitic CA6NM base material. The joint design for the shrouded impeller was finalized based upon the evaluation of a series of multi-gap tee coupons brazed with each alloy. These coupons were peel tested and metallographically evaluated. In addition, lap shear test specimens were made and pulled to finalize the braze alloy selection process. Good braze joints were obtained with both alloys. Based on the test results, the BAu-4 braze alloy was selected for application to full size representative test assemblies. The mock-up shrouded impellers were successfully vacuum brazed and a braze procedure was qualified.