Accession Number:

ADA257569

Title:

Continuous Measurement by Eddy Current Methods of Age Hardening in an Aluminum Alloy

Descriptive Note:

Master's thesis

Corporate Author:

NAVAL POSTGRADUATE SCHOOL MONTEREY CA

Personal Author(s):

Report Date:

1992-09-01

Pagination or Media Count:

46.0

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 operations in real time. As an alloy age hardens its electrical resistivity changes. Hence, the process of aging can be monitored by measuring the change in resistivity relative to that of a non-age hardening material such as fully annealed pure aluminum. A device using two small, spiral-wound probes was designed and used 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 resistivity during the aging process. The monitoring concept was verified. Refinements such as improved impedance bridge circuitry and probe sizetest frequency optimization are needed to unlock its full potential.

Subject Categories:

  • Physical Chemistry
  • Properties of Metals and Alloys
  • Manufacturing and Industrial Engineering and Control of Production Systems
  • Electricity and Magnetism

Distribution Statement:

APPROVED FOR PUBLIC RELEASE