Effect of long-term action of liquid sodium on resistance of steels 17346 and 17349 to low-cycle fatigue

The effect was studied of sodium on AISI 316 type steel fatigue. Steel specimens were exposed to liquid sodium at a temperature of 500 degC for 1000 hours. Afterwards, the specimens were tested for low-cycle fatigue in the air at 550 degC. After crack initiation, chemical analysis was carried out of the specimens and the chemical compositions of the surface layer and the point of crack formation were compared. The results show that in the above conditions, no deterioration of surface layer properties takes place and that there is no significant difference in the life of controls and of the sodium-exposed specimens in low-cycle fatigue. (J.B.)