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Los Alamos National Laboratory The Slitting Method for Residual Stress Measurement:  : Aluminum plate
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Biaxial residual stress measured in aluminum plate before and after stress relief

M. B. Prime and M. R. Hill, "Residual Stress, Stress Relief, and Inhomogeneity in Aluminum Plate," Scripta Materialia, 46, pp. 77-82, 2002. preprint (pdf) . (LA-UR-01-4723)

Two Specimens:

3-inch (75 mm) thick rolled 7050 Aluminum, 6 inch by 6 inch (150 mm by 150 mm) blocks
  • Solution treated and stabilized (7050-T74)
  • Stress relieved (7050-T7451) by stretching 1.5% to 3% in rolling direction

Two cuts each specimen:

  • First cut to measure rolling direction (x) residual stresses.
  • Second cut on half of specimen to measure transverse (y) residual stresses.
  • Cuts made in 1 mm depth increments.
  • Strain at each depth measured on top face (gages shown in picture) and back face (not visible) of specimens.

Photo of
 aluminum block after cutting

Strain data

The Results:

Before stress relief

After stress relief

Residual stresses reduced by about a factor of 10. No problems measuring the stresses, even the low stresses after stress relief. These results are similar to other measurements, see Aluminum, Vol III., Fabrication & Finishing, by ALCOA
NOTE: The raw data from this test and any other data I have can be made available for research purposes. Just email me.