Microstructure and Strength Characteristics of Alloy 617 Welds

Totemeier, T.C. ; Tian, H. ; Clark, D.E. ; Simpson, J.A.

Idaho National Laboratory

关键词: Tensile Properties;    Diffusion;    36 - Materials Science;    Oxides;    Braze;   

DOI  :  10.2172/911266
RP-ID  :  INL/EXT-05-00488
RP-ID  :  DE-AC07-99ID-13727
RP-ID  :  911266

美国|英语

来源: UNT Digital Library

【 摘 要 】

Three types of high-temperature joints were created from alloy 617 base metal: fusion welds, braze joints, and diffusion bonds. The microstructures of all joint types and tensile properties of fusion welds and braze joints were characterized. Sound fusion welds were created by the GTAW process with alloy 617 filler wire. Cross-weld tensile strengths were equal to the parent metal at temperatures of 25, 800, and 1000°C; ductilities of the joints were only slightly lower than that of the parent metal. Failure occurred in the weld fusion zone at room temperature and in the parent metal at elevated temperatures. Incomplete wetting occurred in joints produced by vacuum brazing using AWS BNi-1 braze alloy, believed to be due to tenacious Al and Ti oxide formation. Incompletely bonded butt joints showed relatively poor tensile properties. A second set of braze joints has been created with faying surfaces electroplated with pure Ni prior to brazing; characterization of these joints is in progress. Conditions resulting in good diffusion bonds characterized by grain growth across the bondline and no porosity were determined: vacuum bonding at 1150°C for 3 hours with an initial uniaxial stress of 20 MPa (constant ram displacement). A 15 µm thick pure Ni interlayer was needed to achieve grain growth across the bondline. Tensile testing of diffusion bonds is in progress