Experimental research on fatigue performance of niobium stabilized stainless steel (1.4550, X6CrNiNb1810 mod) relevant for German NPP primary piping has previously demonstrated good long life performance.
Slow rate fatigue tests in 325 °C PWR water are first time presented and discussed in this paper. Good fatigue performance was measured also in hot water. Our experiments give consistently about doubled lives or 50% smaller Fen factors in compared to predictions by NUREG 6909.
Transferability of the laboratory data, reference and design curves together with the proposed Fen evaluation procedure to component evaluation will be discussed.