| Autor: |
Morrison, J., Dixon, S. M., Potter, M. D. G., Davis, C. |
| Předmět: |
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| Zdroj: |
AIP Conference Proceedings; 2/28/2008, Vol. 975 Issue 1, p1192-1198, 7p, 4 Graphs |
| Abstrakt: |
Texture information derived by non-destructive means has been used with limited success to determine formability parameters of sheet metals in a number of specific metallic alloys. Ultrasonic measurement of the zero order symmetric (S0) lamb wave velocity as a function of angle to the rolling direction reveals a metal sheets elastic anisotropy. With knowledge of the behaviour of the single crystal elastic properties in the polycrystalline aggregate, the sheets crystalline texture may be determined. Evaluation of orientation distribution coefficients which sufficiently describe a sheets texture is therefore achieved and can be useful for the non-destructive prediction of formability parameters. EMATs (Electromagnetic Acoustic Transducers) perform this ultrasonic measurement without contact and allows relatively efficient generation of the in plane wavepacket as compared to piezoelectric transducers, whilst allowing for operation on a moving sample. Most importantly, because the (S0) wavepacket employed for ultrasonic testing measures the bulk elastic anisotropy it, easily, samples a statistically significant number of grains through the entire thickness of the sheet. It therefore avoids spurious results which may be obtained when local texture is assumed to provide an indication of a samples global texture as is likely to be the case when diffraction techniques such as XRD (x-ray diffraction) EBSD (electron backscatter diffraction) are used to determine texture at the samples surface. In order to achieve the level of sampling as that achieved ultrasonically with diffraction the sheet must be destroyed in a relatively time consuming measurement. A comparison of elastic anisotropy determined by in-plane S0 wave velocity measurements and plastic anisotropy determined from earing profiles has been performed, which reveals some promising empirical trends. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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