[ materials ]
Fig . 2 . Comparison of the ratio for the reduction of area between different hydrogen charging test methods
UNS 21900 and UNS S31675 , which has the highest
Ni eq of the tested grads , show no martensite , as indicated by the phase map in Figures 7a and 7b . For the high-nickel version of UNS S31603 , EN 1.4435 , no formation of martensite can be observed after the same test ( see Figure 7c ). Figure 7d , the phase map for EN 1.4404 after testing in 87.5 MPa
H 2
, shows large red areas indicating martensite .
SAE J2579 and Ni-equivalent
Applying the acceptance criterion described in SAE J2579 to the in-situ testing in hydrogen
Fig . 3 . UNS S21900 testing at 87.5 MPa and −40 ° C
Fig . 4 . UNS S31675 testing at 85 MPa and −40 ° C
Fig . 5 . Fracture surface of EN 1.4435 : left − cathodic charging , middle − thermal pre-charging , right − testing at 87.5 MPa and −40 ° C
Hydrogen Tech World | Issue 17 | August 2024 45