LOW CYCLE FATIGUE BEHAVIOR IN AIR AND IN PWR WATER OF TYPE 304L AND 316L AUSTENITIC STAINLESS STEELS MANUFACTURED BY HOT ISOSTATIC PRESSING PROCESS

摘要

Because "safety" is still the key point in the Nuclear industry, more than in any others, the use of new materials or new manufacturing methods is really challenging. Among many characterizations required for a new steel grade or a new manufacturing process to be accepted and then introduced in a Nuclear design code, the fatigue properties must be determined with great care. Nowadays, the consideration of the Pressurized Water Reactor (PWR) primary water environment effect on the Low Cycle Fatigue (LCF) behavior of Austenitic Stainless Steels (ASS's) is an important issue for both Nuclear Power Plants (NPP) lifetime extensions and new builds as described in the NUREG/CR-6909. This paper aims to present the LCF behaviors in air and in PWR water at 300°C of type 304L and 316L ASS's manufactured by Powder Metallurgy coupled with Hot Isostatic Pressing process (PM/HIP) and to compare them with those observed on usual ASS nuclear grade products. As already introduced in our previous paper dedicated only to the PM/HIP 304L steel fatigue behavior, it appears that the microstructures, mechanical properties and LCF behaviors in air and in PWR water of both type 304L and 316L steels manufactured by PM/HIP process are better or at least similar to those observed on wrought ASS's.