Comparative study of the behavior of different highly alloyed steels in liquid sodium

By small punch tests performed in air and in liquid sodium at different temperatures and strain rates, the sensitivity of different structural materials to liquid sodium embrittlement was studied: martensitic 9Cr steel, ferrito-martensitic 14Cr steel, ferritic 18Cr steel, austenitic 316LN and 15-15Ti steels, martensitic 9Cr oxide-dispersion strengthened (ODS) steel, ferritic 14CrODS and 18CrODS steels. All materials present ductile mechanical behavior in air. No effect of liquid sodium has been detected for the two 9Cr martensitic steels and the ferritic 18Cr steel. A minor effect of sodium without change in fracture mode or with local brittle fractures has been observed for the 15-15Ti and 316LN austenitic steels, for the ferritic 18CrODS steel and for the ferrito-martensitic 14Cr steel. The ferritic14CrODS steel exhibited a marked liquid metal embrittlement.