D. J. Branagan, W. D. Kiilunen, M. C. Marshall, B. E. Meacham, The NanoSteel Company, Idaho Falls, ID
The existing state of the art for wear protection in PTAW hardfacing is incorporation of high concentrations of WC in an appropriate binder. Besides the high cost of the WC particulates, another disadvantage is that the carbides can sink, segregrate, and / or break down during welding resulting in non-uniform wear rates. This paper reports on a different approach utilizing glass forming iron based alloys which are processed through the atomization of a homogeneous liquid melts. The uniform feedstock powders can be PTA welded resulting in the in-situ formation of high volume fractions of complex, boride, carbide, and borocarbide phases with refined phase sizes from 400 nm to 10 µm. Due to the highly refined structure, the matrix experiences a uniform macrohardness with Rockwell C up to 73 resulting in extremely good wear resistance which is uniform throughout the volume, eliminating the deleterious effects found with existing macrocomposite PTA powders.
Summary: The existing state of the art for wear protection in PTAW hardfacing is incorporation of high concentrations of WC in an appropriate binder. Besides the high cost of the WC particulates, another disadvantage is that the carbides can sink, segregrate, and / or break down during welding resulting in non-uniform wear rates. This paper reports on a different approach utilizing glass forming iron based alloys which are processed through the atomization of a homogeneous liquid melts. The uniform feedstock powders can be PTA welded resulting in the in-situ formation of high volume fractions of complex, boride, carbide, and borocarbide phases with refined phase sizes from 400 nm to 10 µm. Due to the highly refined structure, the matrix experiences a uniform macrohardness with Rockwell C up to 73 resulting in extremely good wear resistance which is uniform throughout the volume, eliminating the deleterious effects found with existing macrocomposite PTA powders.
