On-line measurement of texture, thickness and plastic strain ratio using laser-ultrasound resonance spectroscopy

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DOIResolve DOI: http://doi.org/10.1016/S0041-624X(02)00255-X
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TypeArticle
Journal titleUltrasonics
ISSN0041-624X
Volume40
Issue10
Pages10471056; # of pages: 10
SubjectLaser-ultrasonics; Plastic strain ratio; Texture; Formability; Ultrasonic spectroscopy; Thickness; Crystallographic orientation distribution
AbstractLaser-ultrasound resonance spectroscopy, a non-contact ultrasonic technique, was used to determine reliably and rapidly the crystallographic texture, the average plastic strain ratio, and the thickness of sheet metal on the production line. As with laser-ultrasonics, a short laser pulse is used to generate a wide-band pulse of ultrasound and a laser interferometer is used for its detection. In this paper, a large number of echoes are collected and analyzed together using Fourier techniques to measure the natural resonance frequencies in the thickness of the sheet. One longitudinal and two shear resonance frequencies were measured together with their harmonics. From these frequencies, two crystallographic orientation distribution coefficients, W400 and W420, are obtained, as well as a highly accurate measurement of the sheet thickness that is corrected for changes in ultrasonic velocity caused by texture variations. Using these coefficients, the average and in-plane twofold and fourfold variations of the plastic strain ratio, respectively r̄, Δ2r, and Δ4r, can be evaluated. These parameters are indications of the formability of metals sheets, which is of industrial interest. Measurements on 1 mm thick, low carbon steel sheets have shown the following measurement accuracies: r̄ to within ±0.08, Δ2r, and Δ4r to within ±0.1, and thickness to better than ±1 μm. On-line tests at LTV Steel Company showed that the sensitivity of the apparatus is sufficient to detect systematic variations in texture along the length of similar production coils and that the on-line repeatability for r̄ was of order ±0.02.
Publication date
LanguageEnglish
AffiliationNRC Industrial Materials Institute; National Research Council Canada
Peer reviewedYes
NPARC number21273004
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Record identifier2161d24a-f399-431d-b88b-c06db327987b
Record created2014-12-05
Record modified2016-05-09
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