Friction stir processing of nickel aluminum propeller bronze in comparison to fusion welds
Loading...
Authors
Murray, David L.
Subjects
Advisors
McNelley, Terry
Date of Issue
2005-06
Date
Publisher
Monterey, CA; Naval Postgraduate School
Language
Abstract
Friction Stir Processing (FSP) is currently being considered for use in manufacture of the Navy's NiAl bronze propellers. Incorporating this technology may improve service performance and enable reduction of manufacturing time and cost. This program of research has employed miniature tensile sample designs to examine the distributions of longitudinal properties through the various regimes in a fusion weld. Also, the distributions of both longitudinal and transverse properties throughout the stir zones for selected FSP conditions were examined. Yield strengths were larger in various FSP conditions by at least a factor of two relative to fusion welds. Ultimate strengths were comparable in the weld pool and stir nugget. WidmanstaĆ tten microstructures and microvoid formation and coalescence in the fracture surface resulted in high ductilities in weld metal and the stir nugget. The thermomechanically affected zone of FSP and the heat affected zone of a fusion weld both exhibit low ductility. This may reflect formation of "a" upon heating to temperatures of 800-850 [degrees]C, followed by rapid cooling and transformation of the "a" to form martensitic transformation products in their respective microstructures. For a single-pass raster pattern, transverse ductility is lower than longitudinal ductility. For a multi-pass raster, transverse ductility is higher than longitudinal ductility. For multi-pass raster and spiral patterns in FSP, the data show that the mechanical properties are more nearly isotropic.
Type
Thesis
Description
Series/Report No
Department
Mechanical and Astronautical Engineering (MAE)
Organization
Naval Postgraduate School (U.S.)
Identifiers
NPS Report Number
Sponsors
Funder
Format
xvi, 73 p. : ill. (chiefly col.) ;
Citation
Distribution Statement
Approved for public release; distribution is unlimited.