By -
Date 09-30-2000 12:05
Dear Mr. Lessard,
Ultrasonic testing of Stainless Steels is a very tricky thing,basically due to it's very high grain size.You may have to go in for specialized probe and equipment ( i.e. with high frequency and power ) to over come attenuation problems.Further carrying out UT on a casting is not advisable.Best preferred method may be radiography.Further as you have stated to carry out UT of as rolled and cast materials you may have to establish defect standard which may be a very lengthy and costly process.Alternatively radiography is preferred and easy to do.I have stated the general difficulties encountered with these process and materials.Further you have not mentioned why you propose to do UT ? Is it the customer requirement? Code requirement?
R.MuthuRamalingam
Mr. Ramalingam is right. Ultrasonic test is not advisable in a cast piece, because the results may be quite erratic and difficult to interprete. Radiography, on the other hand, is impossible, or at least quite difficult, in a T joint (Mr. Ramalingam must have overlooked that the joint was a T one). Magnetic particle is impossible on 304 or CF8 steel, because they're non-magnetic. Why don't you try penetrant liquid after each pass? It won't show porosity and other deep defects but at least will show cracks and other superficial defects.
Giovanni S. Crisi
Sao Paulo - Brazil