1.4301 vs 1.4462 Stainless Steel: Chemical Composition and Performance
Grade Identity: 304 Against Duplex 2205
1.4301 and 1.4462 are the two European designations most often weighed against each other in process industry enquiries. 1.4301 is the standard 18-8 austenitic grade, known as Type 304. 1.4462 is a nitrogen-alloyed duplex grade with a roughly equal mix of austenite and ferrite, known commercially as 2205 and listed under UNS S31803 and the tighter UNS S32205 window.
The chemistry explains the difference in behaviour. Duplex steel trades nickel for chromium, molybdenum and nitrogen, which lowers raw material cost while roughly doubling proof strength and improving resistance to chlorides. The cost of that trade is narrower processing windows and lower ductility.
Equivalent Designations
| System | 1.4301 | 1.4462 |
|---|---|---|
| EN | X5CrNi18-10 | X2CrNiMoN22-5-3 |
| ASTM / AISI | Type 304, UNS S30400 | UNS S31803 / UNS S32205 |
| Common trade name | 304 | 2205 duplex |
| Japan | SUS304 (JIS G4303, G4304, G4305) | SUS329J3L class duplex |
| China | 06Cr19Ni10 (GB/T 20878) | 022Cr22Ni5Mo3N (historically written 00Cr22Ni5Mo3N) |
Chemical Composition Compared
| Element, % | 1.4301 (304) | 1.4462 (2205) | Effect |
|---|---|---|---|
| C | 0.07 max | 0.030 max | Lower carbon in the duplex grade reduces sensitisation risk |
| Cr | 17.5-19.5 | 21.0-23.0 | More chromium raises passive film stability and pitting resistance |
| Ni | 8.0-10.5 | 4.5-6.5 | Nickel is the main cost driver; duplex uses about half |
| Mo | Not specified | 2.5-3.5 | Molybdenum resists pitting and crevice attack |
| N | Not specified | 0.10-0.22 | Nitrogen raises strength and delays pitting |
Note the two duplex windows. UNS S31803 permits 21.0 to 23.0 % Cr with 2.5 to 3.5 % Mo, while UNS S32205 tightens the range to 22.0 to 23.0 % Cr, 3.0 to 3.5 % Mo and 0.14 to 0.20 % N to guarantee a stable pitting resistance index. Where the corrosion allowance is tight, order S32205 and say so on the purchase order rather than accepting S31803 as an equivalent.
Mechanical Properties
| Property | 1.4301 (304) | 1.4462 (2205) |
|---|---|---|
| 0.2 % proof strength | 205 MPa minimum | 450 MPa minimum |
| Tensile strength | 515 MPa minimum | 620 MPa minimum |
| Elongation | 40 % minimum | 25 % minimum |
| Hardness limit | About 201 HBW, 92 HRB | Typically capped near 290 HBW |
Those values are the ASTM A240 minima for the plate product form. The practical consequence is a wall thickness or section reduction of 30 to 50 % when a 304 design is converted to 2205, which frequently offsets the higher price per tonne. The trade-off is ductility: 25 % elongation against 40 % means tighter bend radii and more careful handling during cold forming.
Corrosion Performance
A pitting resistance equivalent number puts 1.4301 near 19 and 1.4462 near 35, which is the clearest single indicator of why the duplex grade is specified in chloride service. 1.4301 performs well in fresh water, atmospheric exposure and most food media, but it is vulnerable to chloride pitting and to chloride stress corrosion cracking once temperatures rise above roughly 60 degrees C. 1.4462 resists pitting, crevice corrosion and stress corrosion cracking in chloride-rich, marine and chemical environments, and it tolerates higher chloride levels at higher temperatures.
Two limits apply to duplex. Continuous service temperature is normally held to about 300 degrees C because longer exposure at higher temperature promotes sigma phase formation and embrittlement, and the grade is not suitable for cryogenic service without qualification testing.
Fabrication and Welding
1.4301 is the more forgiving of the two. It welds with standard 308 consumables, forms readily and accepts a wide range of bending radii. The duplex grade requires discipline: heat input and interpass temperature must both be controlled, typically with interpass capped at 150 degrees C, to preserve the roughly 50-50 austenite to ferrite balance in the weld metal and heat-affected zone. Consumables are nitrogen-enriched duplex fillers rather than 308 types, and a small amount of austenite must be present in the weld to avoid cracking.
Post-weld solution annealing is not normally required for 1.4462 if welding is performed within the qualified procedure, which is one reason it is preferred for large fabricated vessels. Pickling and passivation still apply, and the pickling acid selection must account for the higher alloy content.
Frequently Asked Questions
Q: Can 1.4462 replace 1.4301 directly?
A: Mechanically yes, in many cases with thinner sections, but the substitution must be reviewed for weldability, forming limits, magnetic behaviour and service temperature. It is not a simple like-for-like swap on an existing drawing.
Q: Why is 1.4462 stronger than 1.4301?
A: Its duplex structure and nitrogen content block dislocation movement, which roughly doubles the 0.2 % proof strength, while the austenitic grade relies on solid solution strengthening alone.
Q: Is 2205 magnetic?
A: Yes, the ferrite phase makes it ferromagnetic, though less strongly than carbon steel. 1.4301 is essentially non-magnetic in the annealed condition.
Q: Which grade is better for sea water?
A: 1.4462, by a wide margin, and for hot or high-chloride sea water even duplex has limits. 1.4301 is not suitable for permanent sea water contact.
Q: What is the difference between S31803 and S32205?
A: S32205 is the later, tighter composition window within the S31803 range, guaranteeing a minimum pitting resistance index. Specify S32205 when corrosion performance is contractual.
Q: Does the lower nickel content of 1.4462 make it cheaper?
A: The alloying cost per tonne is usually lower, but the delivered cost depends on availability and product form. The section reduction from the higher proof strength is often the larger saving.
