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Re: Small Void/Inclusion detection

Posted by: Godfrey Hands , E-mail: Godfrey@hands-ltd.demon.co.uk, on May 26, 1997 at 09:35:16:

In Reply to: Small Void/Inclusion detection posted by : Gerald Feldewerth on May 23, 1997 at 20:21:21:

: Are standards and techniques available to detect very small voids or inclusions in pure metals using standard C-scan equipment?? The size I am trying to detect is 0.05 to 0.1mm. If this can be accomplished can anyone tell me where I can get flat bottom holes made to use for calibration standards.

: Thanks
: Gerald

Dear Gerald,
It is certainly possible to detect this size of inclusion or void in steel
samples, and some replies have already said that at the higher frequencies,
penetration is very limited.
Together with anothet author, I wrote an article "In search of cleaner
steel" based on our experiences of a similar application to yours. I think
it was in Materials Evaluation September 1995, (ME is sure, date is not).
We were able to clearly show 35 micron defects (0.35mm diameter). With
"Lower" frequencies (25 MHz), these were also detectable up to a couple of
centimetres deep in fine grain steel, but up to about 6 or 7mm deep with
80MHz.
Contact me if you need more info.
regards,

Godfrey Hands

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Comments:
: : Are standards and techniques available to detect very small voids or inclusions in pure metals using standard C-scan equipment?? The size I am trying to detect is 0.05 to 0.1mm. If this can be accomplished can anyone tell me where I can get flat bottom holes made to use for calibration standards. : : Thanks : : Gerald : Dear Gerald, : It is certainly possible to detect this size of inclusion or void in steel : samples, and some replies have already said that at the higher frequencies, : penetration is very limited. : Together with anothet author, I wrote an article "In search of cleaner : steel" based on our experiences of a similar application to yours. I think : it was in Materials Evaluation September 1995, (ME is sure, date is not). : We were able to clearly show 35 micron defects (0.35mm diameter). With : "Lower" frequencies (25 MHz), these were also detectable up to a couple of : centimetres deep in fine grain steel, but up to about 6 or 7mm deep with : 80MHz. : Contact me if you need more info. : regards, : Godfrey Hands

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