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Whether you're a student, engineer, procurement specialist, or curious newbie, you’ve landed here because you want to understand how duplex stainless steels are named and specified. You might stumble upon codes like 2205, S32205, 1.4462, or UNS S32750 and wonder:
Duplex stainless steels are stainless alloys with a mixed austenitic–ferritic microstructure. They combine high strength, good weldability, and excellent resistance to stress corrosion cracking, making them widely used in oil & gas, desalination, chemical processing, and marine industries.
Because they are used globally, duplex stainless steels are designated under several different numbering systems. The same grade may appear with multiple names depending on the standard.
|
System |
Format Example |
Region / Standard |
Key Features |
|
UNS (Unified Numbering System) |
S32205 |
North America / International |
Most universal, chemistry-based |
|
EN Numeric (Europe) |
1.4462 |
Europe (EN 10088) |
“1” = steel; “44” = stainless group |
|
EN Name (Europe) |
X2CrNiMoN22-5-3 |
Europe |
Composition shorthand |
|
ASTM/ASME F-Numbers |
F60 |
USA (forgings) |
Mainly for forged/pressure parts |
|
GB (China) |
00Cr22Ni5Mo3N |
China |
Explicit composition in name |
|
JIS (Japan) |
SUS329J3L |
Japan |
“SUS” prefix for stainless steels |
|
Common Trade Name |
UNS No. |
EN No. |
EN Name |
ASTM/ASME |
GB Code |
JIS |
|
2304 (Lean Duplex) |
S32304 |
1.4362 |
X2CrNiN23-4 |
F68 |
00Cr23Ni4N |
SUS S32304 |
|
2205 (Standard Duplex) |
S32205 |
1.4462 |
X2CrNiMoN22-5-3 |
F60 |
00Cr22Ni5Mo3N |
SUS329J3L / SUS S32205 |
|
2507 (Super Duplex) |
S32750 |
1.4410 |
X2CrNiMoN25-7-4 |
F53 |
00Cr25Ni7Mo4N |
SUS S32750 |
|
Zeron 100 |
S32760 |
1.4501 |
X2CrNiMoCuWN25-7-4 |
F55 |
00Cr25Ni7Mo4WCuN |
SUS S32760 |
|
Ferralium 255 |
S32550 |
1.4507 |
X2CrNiMoCuN25-6-3 |
F61 |
00Cr25Ni6Mo3CuN |
SUS S32550 |
UNS Example: S32205
S = Stainless
32 = Duplex family
205 = Specific grade identifier
EN Name Example: X2CrNiMoN22-5-3
|
Symbol |
Meaning |
|
X2 |
0.02% carbon (very low) |
|
CrNiMoN |
Main alloying elements present |
|
22-5-3 |
~22% Cr, 5% Ni, 3% Mo, N addition |
GB Example: 00Cr22Ni5Mo3N
|
Part |
Meaning |
|
00 |
Ultra-low carbon |
|
Cr22 |
22% chromium |
|
Ni5 |
5% nickel |
|
Mo3 |
3% molybdenum |
|
N |
Nitrogen strengthened |
|
Situation |
Best Choice |
|
International specifications |
UNS (chemistry-based, universal) |
|
European standards |
EN number (e.g., 1.4462) |
|
US forgings / pressure parts |
F-numbers (e.g., F60) |
|
Chinese documentation |
GB codes |
|
Japanese projects |
SUS codes |
