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- since 1996 -

Ultrasonic Sciences Ltd
We specialize in the design and manufacture of automated and semi-automated ultrasonic testing systems, including multi axis, multi channels systems and phased array electronics.
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Technical Discussions
As
As
11:07 Jun-12-2013
Ultrasonic on Aluminum

Hi

A customer has asked me to do Ultrasonic on a 10mm plate V-joint weld in Aluminum.

I've never done UT on anything else than regular carbon steel before and i was trying to find some information regarding ultrasonic inspection on Aluminum but i cant find anything. What i would like to know is if there is something one should think about when performing UT on Alu? or can i just do as i normally do on Carbon steel?

I've checked the probes against a Alu DAC-Holes and it shows no diffrence compared to the CS DAC-hole.

 
 Reply 
 
andrew cunningham
NDT Inspector
Canada, Joined Jun 2008, 238

andrew cunningham

NDT Inspector
Canada,
Joined Jun 2008
238
18:44 Jun-12-2013
Re: Ultrasonic on Aluminum
In Reply to As at 11:07 Jun-12-2013 (Opening).

Simple, calibrate the flaw detector to 100mm in steel with the IIW to find your 0mm. Place the probe on the aluminum to the bottom corner reflector. Adjust the range, to move the bottom corner at mid screen (50mm) of the time base, pull the probe back to confirm that the top corner reflector is at full screen 100mm or at the end of time base.
Read the screen, every 10mm on the time base is 2mm in depth, ie. 50mm on the screen is 10mm depth, 40mm is 8mm deep, 30mm is 6mm, 25mm is 5mm ect ect.
Use the same method with each probe, to confirm the results.
Go to www.practical-ndt.com and look at the sample pages of depthing and positioning.
As per DAC, compare the C/S SDH to the bottom in C/S. If you need to - xdB to make the corner to DAC. On the aluminum put the corner reflector to DAC the +xdB.

 
 Reply 
 
Sudheer Jai Krishnan
Sudheer Jai Krishnan
19:26 Jun-12-2013
Re: Ultrasonic on Aluminum
In Reply to As at 11:07 Jun-12-2013 (Opening).

Hi

Also take the consideration of changing angle accordingly as per Snells Law. Hope you would know it

Regards

Sudheer Jai Krishnan

 
 Reply 
 
andrew cunningham
NDT Inspector
Canada, Joined Jun 2008, 238

andrew cunningham

NDT Inspector
Canada,
Joined Jun 2008
238
00:23 Jun-13-2013
Re: Ultrasonic on Aluminum
In Reply to Sudheer Jai Krishnan at 19:26 Jun-12-2013 .

Knowing the new angle is not required to position the reflector, when following the procedure shown on pages on www.practical-ndt.com these methods work in any velocity. No trig and no Snell's Law.

All the best

 
 Reply 
 
Ed Ginzel
R & D, -
Materials Research Institute, Canada, Joined Nov 1998, 1274

Ed Ginzel

R & D, -
Materials Research Institute,
Canada,
Joined Nov 1998
1274
00:26 Jun-13-2013
Re: Ultrasonic on Aluminum
In Reply to andrew cunningham at 00:23 Jun-13-2013 .

I would also add that in addition to checking the angle, some precaution be made to check for the effects of anisotropy. You may find noticeable differences in velocities depending on the direction of rolling.

 
 Reply 
 
John
John
22:30 Jun-13-2013
Re: Ultrasonic on Aluminum
In Reply to Ed Ginzel at 00:26 Jun-13-2013 .

That's all fine and all, but...
If I were the third party inspector or the customer, you would be booted out of the shop for not using a cal block of the same material or p# grouping as stated in most codes, and for not haveing the correct wedges for the material examined, or obviously no procedure for this inspection.
...just sayen'

Also, depending on type of service the product is for, tungsten inclusions and cluster porosity are very common and can be detremental to service. If backing rings are used they will give geometric indications (both ss & al rings)

 
 Reply 
 
andrew cunningham
NDT Inspector
Canada, Joined Jun 2008, 238

andrew cunningham

NDT Inspector
Canada,
Joined Jun 2008
238
02:19 Jun-14-2013
Re: Ultrasonic on Aluminum
In Reply to andrew cunningham at 00:23 Jun-13-2013 .

When working in a laboratory testing some exotic and expensive metals. It is not cost effective or even possible to have custom made calibration blocks on every metal. One has to learn to find method that will work. Not find an excuse why not to test. NDT “not doing that!!!!”

All the best

 
 Reply 
 
As
As
08:56 Jun-14-2013
Re: Ultrasonic on Aluminum
In Reply to John at 22:30 Jun-13-2013 .

I do have a cal block of the same material with SDH's Ø3mm. But do you need special wedges to test Aluminum?

I was really just wondering if aluminum was a more tricky material to test (like stainless or duplex where it's very important to make a welded reference piece to see that the sound can pass the weld)
The customer gave us 2 welded plates that we can elaborate on, thats why im asking here if it's just to calibrate to the steel V1 block and then establish a DAC to the SDH's on the Aluminum block (the block is not with a weld, just a regular piece with holes in different depths, and then go? It's welding procedures acc. to EN-15609-1

 
 Reply 
 
Amy
NDT Inspector, - -
USA, Joined Jan 2009, 87

Amy

NDT Inspector, - -
USA,
Joined Jan 2009
87
14:03 Jun-14-2013
Re: Ultrasonic on Aluminum
In Reply to As at 08:56 Jun-14-2013 .

I have found aluminum more trying, and sometimes downright frustrating. First off, the wedges I have are custom made for aluminum. I believe the angle is approx. 3 degrees variant in steel (don’t quote me on that, it’s been a while). Secondly, when verifying the Exit Point on an Aluminum IIW, it appeared to be almost off the block. I had to verify on the steel block and calculate angle in my calibration piece. Third, due to the non homogeneous grain structure in the part being tested, standing waves were often created as well as inaccurate measurements due to velocity changes within the part.
I’ve tested materials that have given me no problems, but then will come across an area that gives me the craziest signals you’ve ever seen (mode conversion). Due diligence with verification of signals- plot from both sides whenever possible- as well as a proper procedure and a cal block of the same material is definitely the way to start. An L-Wave transducer has given me more accurate results than a shear.
Good Luck!

1
 
 Reply 
 
Tom Nelligan
Engineering,
retired, USA, Joined Nov 1998, 390

Tom Nelligan

Engineering,
retired,
USA,
Joined Nov 1998
390
15:06 Jun-14-2013
Re: Ultrasonic on Aluminum
In Reply to Amy at 14:03 Jun-14-2013 .

Yes, Ms. Amy, aside from the angle shift encountered when using wedges designed for steel on aluminum, strange things can happen to the apparent beam index point when setting up on an aluminum IIW block. This is because aluminum is typically anisotropic in shear mode, and phase velocity and group velocity differ. There is an detailed analysis of this phenomenon in this journal article:

"Possible Effects of Texture and Texture Gradients on Aluminum Reference Standards" by R. B. Mignogna, K. R. Bernetich, and S. D. Hart.
Review of Progress in Quantitative Nondestructive Evaluation, Volume 9, p. 1765 (1990)

1
 
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