ULTRASONIC TESTING IN AUSTENITIC STRUCTURE. 1

[ibf]

Sometime ago I`ve learned that U.T test in austenitic matrix materials (such as 300 series stainless steel)was not possible. I also learned that today, there are some special transducers able to allow U.T on those type of micro - structures. QUESTIONS: 1. Is it really possible to develop a reliable U.T on 300 series S.S castings ? 2. If "YES" , what specific type of transducer should I apply for (frequency , size , longitudinal beam or shear wave)?

Thank you.

 

[CWIC]

ibf:
Austenitic SS's are commonly ultrasonically tested. I had an unusual SS joint configuration UT'd two weeks ago as the part geometry would not lend itself to RT which would have been much faster and cheaper.

This application was in accordance with the AWS D1.6:1999 Structral Welding Code-Stainless Steel. There is an entire section on UT (Section 6, Part C) of austenitic materials. Castings are also listed under this code in Table 3.2 (Prequalfied Austenitic Stainless Steels). Typical specifications for castings are A 351 and A 743. Additional specs. are listed for cast pipe.

UT equipment and transducer selection will depend on part geometry and surface condition as well as several other factors. D1.6:1999, Section 6.15 provides information on the equipment and transducers for structural applications but can be tailored to your product. This code permits transducers as small as 1/4" and frequencies as high as 6 MHz.

Don't forget to try RT if much grass/hash is present during your UT inspection.

 

[GRoberts]

here's some info regarding that specific subject that I stumbled onto the other day.

http://www.ndt.net/article/v05n10/versp/versp.htm

 

[CWIC]

Hi GR:
This is an interesting article. What I find even more interesting is the varied opinions on this subject. I noted above I recently had a SS weld (316L) UT per my clients request. There was quite a debate about the validity and sensitivity of UT for this material.

The NDT company I use has tested many austenitic welds before (including many of my own projects) and was able to provide a procedure deemed satisfactory by the project engineer.

The article you posted only adds to my confusion although I understand the theory behind the limited use of UT for this material. There is quite a bit of contradicting info on this test method and material. I put a star next to you for providing more on this topic. Maybe the article will help ibf with his/her query.

 

[ibf]

Thank you CWIC & GROBERTS for your input. I will try to guide my next steps based on both of your inputs.

ibf.

 

[GRoberts]

As a general rule here at work, we don't UT austenitic stainless because I am told, that "the grain size is too large, so you can't get any meaningful results". I don't know if we use the most current technology though.