Continuous measurement by eddy current methods of age hardening in aluminum alloys
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Authors
Esarey, John Gilbert
Subjects
Eddy current monitoring
Resistivity measurement
Age hardening
Precipation hardening
Resistivity measurement
Age hardening
Precipation hardening
Advisors
McNelley, Terry R.
Date of Issue
1992-09
Date
September 1992
Publisher
Monterey, California. Naval Postgraduate School
Language
en_US
Abstract
Many materials processing operations such as age hardening heat treatments typically involve following predetermined time and temperature schedules to obtain the desired final material properties. The intelligent processing approach is to develop sensors for monitoring of material response to processing operation in real time. As an alloy age hardens its electrical resistivity changes. Hence, the process of aging can be monitored by measuring the change is resistivity relative to that of a non-age hardening material such as fully annealed aluminum. A device using two small, spiral-wound probes was designed to induce eddy currents within the pure aluminum and the aging alloy. The probes were incorporated as elements in an impedance bridge circuit. The bridge unbalance voltage decreased in value over time indicating decreasing relativity during the aging process. The monitoring concept was verified. Refinements such as improved impedance bridge circuitry and probe size/test frequency optimization are needed to unlock its full potential.
Type
Thesis
Description
Series/Report No
Department
Mechanical Engineering
Organization
Naval Postgraduate School
Identifiers
NPS Report Number
Sponsors
Funder
Format
38 p.
Citation
Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.