Re: Ultrasonic Ispection of Welds in Duplex Steel : : : Can anyone help me in this subject i.e.
: : : Are there any special equipment required for the UT examination of duplex welds in the past it was not considered possible due to the grain structure but we have a client that insits that it can be inspected and say that there is Equipment on the market.
: : : The welds to be examined are 15mm to 20mm thick
: : : Pressure vessels circumferential welds and nozzle welds.
: : ---------------------------
: : I hope you found already the below article on NDTnet.
: : http://www.ndt.net/article/pow1297/schmid/schmid.htm
: : Ultrasonic Testing of Austenitic and Dissimilar Metal Welds.
: : By Rudi Schmid. A translated chapter of the German Book: "Ultraschallprüfung von austenitischen Plattierungen, Mischnähten und austenitischen Schweißnähten", Eberhard Neumann et al,.
: : Rudi Schmid worked with Siemens AG Power Generation Group (KWU) Erlangen
: : (http://www.ndt.net/exhibit/cust_ky/sie_ky.htm).
: : Testing of austenitic and dissimilar metal welds is generally limited, since
: : truly homogeneous ultrasound wave propagation does not exist. The testing and
: : manufacturing methods must find economical solutions for achieving testability for
: : those components.
: : In this chapter the author focus on practical solutions, for instance
: : Probes and Testing Techniques, Test Results of austenitic Welds, Dissimilar Metal
: : Welds and Claddings; Comparison of EMAT- SH- and SEL Technique.
: : Rolf
: The welds in duplex steel normally used in the offshore industry is by no means comparable to the austenitic or nickelbase welds, which are known in the nuclear industry. The welds in duplex steel vessels and piping up to a thickness of 70 mm may in many cases be examined with traditional probes and techniques used for the examination of ferritic welds.
: It is, however, highly recommendable to perform an accurate measurement of transfer losses including verification of the probe angle on the actual component. Particular attention has to be paid to the state of heat treatment, which may cause considerable changes.
: The actual thickness should not cause any problem with 2 MHz angle probes. Normally the attenuation of the material is so low, that even the TOFD technique may be applied as pointed out by Jan Verkoijen.
I think that some of the authors respectively readers are using the terms 'duplex steel' and 'bimetallic weld' in equal sense or meaning. But this is an error as 'duplex steel' absolutely has nothing to do with austenitic or bimetallic (i.e. joint between austenitic and carbon steel) materials. So I think that Bjarne is right and Rolf is wrong (only this time, of course).
Uli Mletzko, MPA, University of Stuttgart, Germany