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ULTRASOUND INSTITUTE
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Technical Discussions
M.Kovacik
M.Kovacik
00:14 Oct-03-2004
UT and magnetic field

Dear colleagues

Recently,I have been confronted by a problem of UT testning steel material under strong magnetic fields. My question is : may magnetic fields produced by strong DC current (100kA) have any effect on the propagation and attenuation of 2MHz - 10 MHz ultrasonic waves?

Thanks for any answer.





 
 Reply 
 
Pim van Andel
Pim van Andel
02:32 Oct-06-2004
Re: UT and magnetic field
There could be some influence:
A DC field of this strength may magnetise a substantial volume of steel. Ultrasound passing through this volume generates eddy currents (compare the EMAT transducer principle)Energy loss by the eddy currents may attenuate the ultrasound.


----------- Start Original Message -----------
: Dear colleagues
: Recently,I have been confronted by a problem of UT testning steel material under strong magnetic fields. My question is : may magnetic fields produced by strong DC current (100kA) have any effect on the propagation and attenuation of 2MHz - 10 MHz ultrasonic waves?
: Thanks for any answer.
:
:
------------ End Original Message ------------




 
 Reply 
 
Chris Coughlin
Chris Coughlin
05:08 Oct-07-2004
Re: UT and magnetic field
If the field's strong enough, it can change the acoustic velocity of the steel, because of the stresses (e.g. magnetostriction) a magnetic field can induce in a ferromagnetic material. This "magnetoelastic effect" is sometimes used to measure stresses in ferromagnetic steels.

Hope this helps,
Chris

----------- Start Original Message -----------
: Dear colleagues
: Recently,I have been confronted by a problem of UT testning steel material under strong magnetic fields. My question is : may magnetic fields produced by strong DC current (100kA) have any effect on the propagation and attenuation of 2MHz - 10 MHz ultrasonic waves?
: Thanks for any answer.
:
:
------------ End Original Message ------------




 
 Reply 
 
Pim van Andel
Pim van Andel
02:11 Oct-08-2004
Re: UT and magnetic field
And the change in velocity is (much?) less then 1% ?

----------- Start Original Message -----------
: If the field's strong enough, it can change the acoustic velocity of the steel, because of the stresses (e.g. magnetostriction) a magnetic field can induce in a ferromagnetic material. This "magnetoelastic effect" is sometimes used to measure stresses in ferromagnetic steels.
: Hope this helps,
: Chris
: : Dear colleagues
: : Recently,I have been confronted by a problem of UT testning steel material under strong magnetic fields. My question is : may magnetic fields produced by strong DC current (100kA) have any effect on the propagation and attenuation of 2MHz - 10 MHz ultrasonic waves?
: : Thanks for any answer.
: :
: :
------------ End Original Message ------------




 
 Reply 
 
Chris Coughlin
Chris Coughlin
03:14 Oct-08-2004
Re: UT and magnetic field
Granted, the effect is small (delta V/V ~10^-5 normally), but the original question was "any effect," not "any significant effect." ;-)

Take care & have a good weekend!

--chris

----------- Start Original Message -----------
: And the change in velocity is (much?) less then 1% ?
: : If the field's strong enough, it can change the acoustic velocity of the steel, because of the stresses (e.g. magnetostriction) a magnetic field can induce in a ferromagnetic material. This "magnetoelastic effect" is sometimes used to measure stresses in ferromagnetic steels.
: : Hope this helps,
: : Chris
: : : Dear colleagues
: : : Recently,I have been confronted by a problem of UT testning steel material under strong magnetic fields. My question is : may magnetic fields produced by strong DC current (100kA) have any effect on the propagation and attenuation of 2MHz - 10 MHz ultrasonic waves?
: : : Thanks for any answer.
: : :
: : :
------------ End Original Message ------------




 
 Reply 
 

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