Grade 904L stainless steels have excellent resistance to warm seawater and chloride attack. The high resistance of grade 904L against stress corrosion cracking is due to the presence of high amounts of nickel in its composition. Moreover, the addition of copper to these grades develops resistance to sulphuric acid and other reducing agents in both aggressive and mild conditions.
The corrosion resistance of grade 904L is intermediate between super austenitic grades, with 6% molybdenum content, and standard 316L austenitic grades. Grade 904L is less resistant to nitric acid than grades 304L and 310L, which are free of molybdenum. This steel grade needs to be solution treated following cold working, to achieve maximum stress corrosion cracking resistance under critical environments.
Heat Resistance
Grade 904L stainless steels offer good oxidation resistance. However, the structural stability of this grade collapses at high temperatures, particularly above 400°C.
Composition ranges of grade 904L stainless steels
Grade
C
Mn
Si
P
S
Cr
Mo
Ni
Cu
904L
min.
-
-
-
-
-
19
4
23
1
max.
0.02
2
1
0.045
0.035
23
5
28
Typical physical properties of grade 904L stainless steels