09:45 Feb-27-2010 S.V.Swamy Engineering, - Material Testing Inspection & Quality Control Retired from Nuclear Fuel Complex , India, Joined Feb 2001 784
Re: About the detecting depth using UT technique for austenitic stainless steel and nickel base alloyIn Reply to QI at 01:40 Feb-27-2010 (Opening).
Your question is not clear. Did you mean the feasibility of getting a back wall echo from a 400 mm thick Incoloy 800H plate?
If that is what you meant, it is possible using the right probe and instrument combination.
Or are you interested in detecting a discontinuity in such a plate? If this is what you meant, the size of a discontinuity that can be detected depends on several factors including the surface condition, grain size etc. Planar indications of a smaller diameter can be detected compared to spherical / round indications but there can be exceptions too! Since you are discussing a plate, it is expected that both the surfaces are accessible and thus the metal path that needs to be detected is a little more than half the thickness, thus about 250 mm in your case.
If you clarify the question / application, better answers will come.