Matched by chemical composition and mechanical properties, not a formal equivalence claim. Always verify against the applicable standard before substitution.
Chemical Composition (%)
C
Cr
Mn
Mo
Ni
P
S
Si
0.38-0.43
0.70-0.90
0.65-0.85
0.20-0.30
1.65-2.00
<=0.025
<=0.025
0.15-0.35
More data from SAE J404:2009
From the standard
Other composition limitsfrom Table 1 and its notes
UNS number
G43406
Values
Cast or heat chemical ranges; P and S are maximum limits
Incidental elements
Cu 0.35, Ni 0.25, Cr 0.20, Mo 0.06 (percent max, for elements not specified or required)
Elements to be reported
C, Mn, P, S, Si, Al, Cu, Ni, Cr, Mo, Nb (Cb), Ti, V, B and N, whether specified or not; Si, Cu, Ni, Cr and Mo below 0.02% may be reported as <0.02%; Al, Nb, Ti and V below 0.008% as <0.008%; As and Sb if the purchaser specifies
Melting practice
Electric furnace steel, 0.025 P and 0.025 S maximum
Limits are subject to the standard variations in check analysis of SAE J409. Lead (0.15 to 0.35%, letter L between the second and third digits, for example 51L40) can be added to improve machinability. When agreed by purchaser and supplier, other silicon ranges are permitted. P and S in the table are default values; alternate levels are agreed between purchaser and supplier, with typical values P 0.030 max and S 0.035 max for flat rolled products and P 0.040 max and S 0.050 max for ASTM long products.
Source: SAE J404:2009, Table 1 and its notes
Active SAE J404:2009 E4340 Listings on M-EX (For Sale)