Ultrasonic testing in thin sheets of Alloy Steel 1

[Amitesh8532]

Dear All!
Greeting from my side!!
I have gone through the Ultrasonic testing of the Alloy steel with Plate thickness > 6 mm. Now I am exploring to do the UT in final products [as thin sheets of Alloy Steel] in thickness 2-4 mm. First I have done with UT in 2-4 mm thickness with conventional methods but the echoes that we receive is not coherent. So, my First Question is is there is any process/ASTM standards to carry out the UT test in 2-4 mm thickness? What is the type of machines required do the UT testing in 2-4 mm thickness? And if not, what is the possible ways to do the UT?
All suggestions and solution are welcome. Thanks you all !!

 

[racookpe1978]

What defects are you looking for in that thin a piece of rolled steel?

99% of the UT signal is reflecting back from the far wall of the 2-4 mm thin plate, right?

So the "signal" reflecting from a potential defect inside the 2-4 mm plate could only be "heard" if the return signal reflected from the defect were big enough to override the side-echos and spreading from all areas of the "good" metal around the defect that are returning the reflections from the far side. So an internal defect of some kind (tearing ?, delamination ? potholes? weld pin-pricks?) could only be 1/2 mm to 1 mm thick (or it doesn't penetrate through to the surface) but has to be spread out 2-3 mm across the inside of the rolled plate to return a signal that can be distinguished from the farside reflections around the defect.

Frankly, I don't think you will find anything with UT because any meaningful defect inside that thin a plate will actually be a surface defect.

 

[EdStainless]

What are the calibration notches that you are using?
As rac said, most of your signal will be from the back side of the surfaces.
So unless the surfaces are very smooth that noise will swamp the indications that are looking for.
I have a hard time thinking of what you will be looking for.
We UT thin wall tubing. We use cal notches 0.002" (.05mm) and we fight background noise all of the time.

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P.E. Metallurgy, Plymouth Tube

 

[Amitesh8532]

I am using 1.2 mm FBH for multiple discontinuity and 2 mm FBH (Flat Bottom Hole) for single/point discontinuity.
And I am trying with AMS 2632 standard.

 

[MagBen]

This is D3 or D5 (single defect) level, pretty much a basic requirement on internal defects, not tough. I am pretty sure you can do with 4mm plate. Do you also have axial and shear wave testing requirements on surface defects?
2mm might be challenge. If using immersion method, surface finish needs max 125RA (140RMS), smoother the better. you may also use high frequency to improve resolution. Contact method will be less strict on surface condition.

 

[Amitesh8532]

Thanks a lot to all of you for your valuable support and prompt responses!!
Mr. MagBen, can you please provide some more insights on the doing the UT with 1.2 mm FBH and 2 mm FBH on 4 mm thickness!
Have any one tried this UT testing before? Please provide some reference publication (if any) for my reference.
Thanks a lot once again!!

 

[EdStainless]

For thin wall tube we use surface finishes or 32uin and finer, we prefer below 20uin.
Why are you using such huge indications?
Are you really looking for something that is 50% of the sheet thickness?
More typical would be 10% thickness but not less than 0.10mm as ref notches/holes.

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P.E. Metallurgy, Plymouth Tube

 

[MagBen]

Check with plate, or lamb wave test for thin material. The smallest FBH we use is .4mm that is D1 level

 

[Amitesh8532]

Thank you MagBen!!
Is there this applicable in commercial scale or any industry person is using this method for UT testing as of now?
And please also provide some details on this. I have some papers and thesis but till now I didn't get enough idea how to perform on the sheets of dimension like 3.9 X 1000 X 6000 mm. Thanks!

 

[WKTaylor]

What US-NDI process are You intending to use? IE... examples...

NAS824 INSPECTION, ULTRASONIC, WROUGHT METAL
AMS-STD-2154 Inspection, Ultrasonic, Wrought Metals, Process for
AMS2632 Inspection, Ultrasonic, of Thin Materials 0.50 Inch (12.7 mm) and Under in Cross-Sectional Thickness
AMS2634 Ultrasonic Inspection Thin Wall Metal Tubing
Etc...

For grins... interesting reference...
Advanced Ultrasonic Methods for Material and Structure Inspection
ISBN-13: 978-1905209699
ISBN-10: 190520969X

Regards, Wil Taylor

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