ASTM A959:2011 651: Precipitation hardening stainless steel type 651 (UNS S63198) with the composition limits of ASTM A959-11. Carbon 0.28-0.35% and chromium 18.0-21.0%.
Matched by chemical composition and mechanical properties, not a formal equivalence claim. Always verify against the applicable standard before substitution.
Chemical Composition (%)
C
Cb
Cr
Cu
Mn
Mo
Ni
P
S
Si
Ti
W
0.28-0.35
0.25-0.60
18.0-21.0
<=0.50
0.75-1.50
1.00-1.75
8.0-11.0
<=0.040
<=0.030
0.30-0.80
0.10-0.35
1.00-1.75
More data from ASTM A959:2011
From the standard
Other composition limitsfrom Table 1 and its footnotes
UNS number
S63198
Metallurgical class
Precipitation hardening grade: basically austenitic or martensitic, hardenable by precipitation (age) hardening
Type
651 (common type number, not a trademark, widely used; not associated with any one product)
Values
Maximum unless a range or minimum is shown; where two limits are shown for the same element in one grade the more stringent applies
Other elements (as printed)
W 1.00-1.75, Ti 0.10-0.35, Cb 0.25-0.60
These are the recommended composition limits of the A959 guide, intended for adoption by standards for stainless steel products; they are not a product specification.
Source: ASTM A959:2011, Table 1 and its footnotes
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