Re: UT of Monel 400/carbon steel dissimilar metal welds ----------- Start Original Message -----------
The best way to examine the Bi-metallic weld is using focused Refarcted L-Waves establishing a Depth Calibration.
Two Excellent probes are the HALT probes from Krautkramer and the RTD Probes. The HALT probes are Piezeoelctric composite.
The HALT probes have refrcated angles of 80L,70L,60L, and 45L, with respective focal depths .200, .400, .800 and 1.2 inches.
Frequencies are 2.25, 3.5, 5, and 7.5 Mhz.
The RTD Probes have a variety of focal depths and frequencies.
The RL technique is very effective for detection and for depth sizing using a Time of Flight (TOF) method.
Another consideration, is using Phased Array with an L wave Sectorial Scan. Check out the OmniScan with RDTech.
The key to this L-wave examination is the refracted angle, focus depth, and frequency of the transdcuer. The 3.5 MHz works well with inconels of about 1.5 inches thick.
These techniques work very well with the Overlay Examination.
I conduct Advanced UT training forDetection, Sizing and Weld Overlay Examinations.
However, if you have a good understanding of L-waves and mode conversion effects, you should not have a problem with these examinations.
Go the the Publication Section of NDT.net and view the Advanced Flaw Sizing Handbook I wrote. It will explain the uses, calibration and application for the Refracted L-wave techniques.
J. Mark Davis
: Hello all,
: Does anyone have any experience with the UT of dissimilar metal welds between DH-36 mild carbon steel (this is a shipbuilding grade, 50ksi steel) and Monel 400?
: The weld configuration will be DH-36 plate (thicknesses 1" to 1-1/2" <25 to 38mm>) welded to a Monel 400 ring-shaped forging, with all joints being T-joints. Scanning will not be possible from the forging due to the configuration.
: In addition, I will need to UT examine a Monel 400 overlay of appr. one inch (25mm) in thickness applied to a DH-36 base material.
: Any information/advice/ideas are greatly appreciated.
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