De-Sensitization of Aluminum Alloys using Pulsed Electron Beams
The U.S. Naval Research Laboratory (NRL) has developed a new method of de-sensitizing sensitized 5XXX-series aluminum alloy plates on a single side without inducing bulk heating throughout the panel. This is accomplished by locally heating the near-surface volume to high enough temperatures (e.g., > 250 ºC) to dissolve the beta phase using pulsed electron beams. This reduces or eliminates grain boundary beta phase at the surface, where intergranular corrosion and stress-corrosion cracking occurs resulting in degraded service life of the alloy plate. This method allows for the controllable reduction in the degree of sensitization (DOS) by varying at least one of the following electron beam parameters: voltage, current density, pulse duration, pulse frequency, and total number of pulses. With an apparatus with a foil electron beam window, operation in ambient air would be possible; thus a portable eBeam system is within reason.