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461 views
08:57 Dec-18-2000
kamchiu
different volecity in steel

Hello,

Do anybody know why there are different velocities of ultrasonic waves when applying the probe in different directions of the sample?

Thanks

Kamchiu


 
01:24 Dec-18-2000

Udo Schlengermann

Consultant, -
Standards Consulting,
Germany,
Joined Nov 1998
174
Re: different velocity in steel
: Hello,

: Do anybody know why there are different velocities of ultrasonic waves when applying the probe in different directions of the sample?

: Thanks

: Kamchiu

reply by Udo Schlengermann

Hello,

Supposing you are talking about the same wave mode, e.g. transverse waves, velocity will depend on direction, if the elastic constants of the material - here steel - are different in different directions, this is called anisotropy.

Ultrasonic waves are elastic waves. So their velocity depends on the elastic constants of the material and the density. If these parameters change for different directions, e.g. parallel and perpendicular to rolling direction of a steel plate, then the velocities will change with direction or angle of incidence (acoustic anisotropy).
Anisotropic steels will even show birefringence, i.e. two reflected echos caused by a single transmitted pulse.
Only with isotropic steels the velocities are independent of direction.

Kind regards

Udo Schlengermann


 


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