USA as Represented by Secretary of the Navy

Derek Horton

Ronald L Holtz

Kathryn J Wahl

John D Sethian

Frank Hegeler

Matthew C Myers

Mathew Wolford

Alexis C Lewis

A non-destructive method for assessing the 'degree of sensitization' of ship structures formed from aluminum-magnesium marine service alloys. Features of the method include (1) selective etching of beta phase in a sensitized aluminum-magnesium alloy (2) metallographic recording of the etched surface; (3) image enhancement to produce high-contrast binary images of etched and unetched areas; (4) image analysis of the enhanced images using line segments along grain boundaries to provide statistical information about the grain boundary beta phase percentage and (5) calibration, whereby the grain boundary beta phase percentage is converted to an expression of the degree of sensitization in the sample.

Surface metallographic method for characterizing the degree of sensitization of aluminum-magnesium alloys

A method for desensitizing an aluminum alloy is presented. A desired location on the surface of an aluminum alloy sample is exposed to a controlled pulsed electron beam. The pulsed electron beam heats a shallow layer of the metal alloy having a desired depth at the desired location on the surface of the sample to a temperature between a solvus temperature and an annealing temperature of the metal alloy to controllably reduce a degree of sensitization of the metal alloy sample at the desired location, an extent of a reduction in the degree of sensitization being controllable by varying at least one of a voltage, a current density, a pulse duration, a pulse frequency and a number of pulses of the electron beam.

Desensitization of aluminum alloys using pulsed electron beams

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Alexandria, VA, United States of America

Derek Horton