Underclad cracking (UCC) in pressure vessel steels and their assessment on structural integrity is reported important. The residual strength of the clad is reduced due to the presence of UCC, hence its innocuity/behaviour of UCC needs to be demonstrated. Fabrication experience and testing data shows that SA-508 is susceptible for UCC. Steels like A-304, SUS-329, Incoloy-825 cladded with SA-508 were studied. Detection of UCC is possible using UT by a longitudinal angle beam probe but the assessment of the risk of UCC extended by fatigue and subsequent fracture in pressure vessel is considered more important. Hence a combination of NDT and DT becomes inevitable here. An experimental-analytical hybrid type of investigation was carried out on claddings and fracture parameters like CTOD and J were calculated. Results obtained by these procedures compare quite favourably. An attempt was made to calculate the fracture parameters through NDT technique too. Based on the results the significance of UCC on structural integrity is discussed.
Publication Source: Trends in NDE Science & Technology; Proceedings of the 14th World Conference on Non-Destructive Testing, New Delhi, 8-13 December 1996.Vol. 5, pages 1 - 10 Publisher:Ashgate Publishing Company
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