Ultrasonic Inspection

"There is an option that 317L steel can not be inspected by this method"

This blew me away also, and I passed to see what the real metals guys thought before I responded.

Just makes me very curious.

Sorta like a question asked on another forum about scatter while trying to do UT on pipe coated with Carboline with Glass Flakes that show all of the evidence of a bad prep and application, not necessarily bad information, just not enough initially presented.

Usually, ultrasonic inspection is not worth while on stainless steel material especially when you are going for ultrasonic flaw detection & sizing. This is because of high attenuation of ultrasonic waves in stainless steel material. It really demands for a skilled inspector. If feasible in your case, you may go for radiography. This depends upon the type of defect you are expecting / looking for. Regards, Ashfaq Anwer http://forums.thepetrostreet.com

GA, for a correct, blunt, and to the point answer.

The "option" statement through me for a loop.

Thanks, but sometimes the truth hurts, but that is a good thing! The pain makes sure you remember the answer next time around.

Thanks for confirming the facts as you (we) all know them Rorschach.

Appreciate the support.

milo

Thank you all for the inputs!

I meant "Opinion" not "Option". This was a typo. I got this question that 317L may not be inspected by UT and was asked to confirm. It seemed that is not the case.

I recommend TEI Analytical Services…

Have used this company many, many times with great results…

Contact Scott Weiss

Another great company for sure, I have used their UT department in the past and been very pleased for the most part.

Here are a few other companies to check out.

http://www.rndt.net/

Fred Raco, the owner is top notch and I have used these guys for Surface and RT Inspections.

http://www.itls-labs.com/

Marty Wenzig, the director and his crew are pretty sharp guys.

http://www.tensile.com/index.htm

James Smith and his staff have been in various aspects of metallurgical issues in the past.

My advise is to contact the local chapter of the ASNT - the American Society for Non- Destructive Testing. I feel confident that they can either answer your question, or recommend someone who can. If you are in contact with a level III in UT, that person will most likely have a good answer for you.

Hello! I don't think anyone has mentioned that the difficulty of UT with SS is with welds and castings - because of possible large grain size. Large grains scatter the ultrasound making attenuation so high that even small thicknesses cannot be tested.

Wrought products with a fine grain size do not present this problem.

John Rodda

John, thanks for your contribution! Your additional sensemaking is welcome.It was my read of the initial post that this was a 'shaft' which in my mind means machined from barstock or forging not "weldment."

The semifinished billets or blooms that I mentioned as testable by the immersion method are in fact in the as cast condition.

Thanks again for this.

milo

That was my impression as well Milo. As-Cast billets I would expect would also have large unrefined grain structures as well. If they are UT inspectable, I would expect a weldment could be as well since a weld is nothing more than a small continuous casting with some interesting HAZ issues. It might take a skilled operator to do so, but if it is merely a grain size issue, clearly your semi-finished blooms/ingots are proof that grain size alone should not be an issue. Now if the issue is a HAZ in which the grain size changes over a very small area then I could see where that might give a false positive indication of a crack where there is none. Is that the issue that John is alluding to?

I'm hoping to find out.

Milo

Rorschach, it is a mainly a problem of attenuation. Stainless steel is anisotropic, and the velocity of ultrasound is different in different directions in the crystal. This means that, once the grain size approaches the wavelength of the ultrasound (say 1/10th of the grain size or larger - the larger the worse it is), the ultrasound is partially reflected, partially refracted, and partially mode converted (from a shear wave to a compression wave or vice versa) with a change of direction at each grain boundary, resulting in a lot of noise and little penetration, as well as false indications (spurious signals).

Obviously, long wavelength (low frequency) ultrasound will improve the penetration, but reduces sensitivity (small flaws will be hidden in the noise). Welds can be uninspectable or inspectable only with difficulty. I have no experience with ingots or castings, but again it is a grainsize/attenuation issue, with an important variable being the angle of incidence relative to the grains for columnar grains.

John Rodda

what about a multi-frequency or a frequency swept scan? Would that help any?

Multi-frequency would not help - the higher frequencies would just give more noise. In practice a low frequency compression wave angle beam probe is used. Compression waves travel at about twice the speed of shear waves, so have longer wavelengths. Compression waves are standard for probes producing beams normal to the test surface, but when testing at an angle can give some mode conversion on reflection, resulting in 2 beams propagating and confusion. Therefore shear waves are almost always used for testing at an angle - but special compression wave angle probes are available for testing SS welds. (Welds have to be tested with angle probes because of lack of good contact of a probe sitting on the weld bead surface, but ingots and castings would be tested mostly with normal probes.)

I have a friend, now retired and rebuilding 4 wheel drive trucks as a retirement income booster in the wilds of Wyoming, who used ET for castings.

He was USAF trained and continued this after he left the military.

As a guy who had only used or seen ET on tubulars, I never quite got the hang of it, but he was contracted to the FAA and a few airlines.

ET? do you mean Eddy Current?

Yes sir.

While I have not done it myself, I know Eddy Current Inspection is used on Wheel rims for Aircraft to check for cracking in the tire rims.

My friend also did a lot of landing gear from the die caster to annual inspections.