Environmental Fatigue – Early Results Revisited

VTT started in 1999 developing capability to conduct LCF tests in hot water environments and published first EAF results for 316NG in the 3rd Int. Conf. on Fatigue of Reactor Components (Seville 2004) and supplemented by results for titanium stabilized alloy 321 in paper PVP2006-93833. This paper revisits these 20 years old experiments in aim to put their significance in perspective and to underline relevant findings on different performance of the stabilized and non-stabilized alloys. An interesting difference in secondary hardening was measured: alloy 321 hardens at RT air, but 316 NG rather in hot water. This finding was in line with the GE (Solomon & Amzallag) results at the time and with more recent research. A warning on misinterpretation of the results is delivered. The tests were properly and reproducibly conducted, but – as most of the EAF facilities – the prototypical EAF devices were not able to provide compliance with the standard LCF test procedure of ASTM E606. The author recommends that the results presented in PVP2006-93833 should not be considered as quantitatively valid fatigue data, but comparison of the material responses within this set should be fine.