2304 Stainless Steel
A lean duplex stainless steel
Typical values for the temper in the title
2304 is a lean duplex: about 23% chromium, 4% nickel and a little molybdenum. It keeps the high strength of duplex (yield roughly twice that of 304), with corrosion resistance close to 316L in many environments, at a lower price than 2205.
It is used in structures, tanks, bridges and water systems, where the strength allows savings in weight and material.
Mechanical and physical properties
| Property | Value | Note |
|---|---|---|
| Tensile strength Rm | 600-750 MPa | |
| Yield strength Rp0.2 | 400-450 MPa | |
| Elongation A | 25% | |
| Hardness | 220-240 HB | |
| Modulus of elasticity E | 200 GPa | |
| Density ρ | 7.78 g/cm³ | |
| Machinability | 45% | relative rating in the site database |
Chemical composition (wt %)
| Element | Range | Role |
|---|---|---|
| Cr chromium | 21.5–24.5 | corrosion resistance |
| Ni nickel | 3.0–5.5 | balances ferrite and austenite |
| Mo molybdenum | 0.05–0.60 | a little |
| N nitrogen | 0.05–0.20 | strength and stability |
| Cu copper | 0.05–0.60 | |
| C carbon | max 0.030 | |
| Mn manganese | max 2.50 | |
| Si silicon | max 1.00 | |
| Fe iron | balance |
Ranges per ASTM A240 (plate and sheet), the same in A789/A790 for tubing.
Conditions and heat treatment
Duplex is supplied solution annealed and rapidly cooled, to get a structure of about half ferrite and half austenite.
| Condition | Properties | When to choose it |
|---|---|---|
| Solution annealed | yield roughly twice that of 316L | the normal delivery condition |
| Not hardenable by heat treatment | — | strength comes from the two-phase structure and nitrogen |
| Range to avoid | prolonged exposure at about 300–1000 °C forms brittle phases | so the upper service limit is about 250–300 °C |
Applications
- Structures and bridges
- Tanks and storage vessels
- Water and wastewater systems
- Heat exchangers
- Weight-sensitive structures
Fabrication
Welding
Welds well, with a nickel-overalloyed filler (usually ER2209), so the weld has enough austenite. Keep heat input controlled, and check the ferrite content of the weld.
Machining
Harder than 316L because of the high strength. Sharp tools, low speeds and a steady feed.
Corrosion
Excellent resistance to chloride stress corrosion cracking, where ordinary austenitic stainless is weak.
Compared with similar materials
| Material | Rm / Rp0.2 | Welding | When it is the better choice |
|---|---|---|---|
| 2205 Duplex | 620–880 / 450–620 MPa | Good — ER2209 | more resistant, with molybdenum · material page |
| 304 / 304L | 515–620 / 205–310 MPa | Good — ER308L | cheap, much weaker · material page |
| 316 / 316L | 485–620 / 170–310 MPa | Excellent — ER316L | similar resistance in many environments, weaker · material page |
Common mistakes
Using duplex above about 300 °C
With prolonged exposure, brittle phases form. For heat, austenitic stainless.
Welding with matching (not overalloyed) filler or uncontrolled heat
The weld may be ferrite-rich, brittle and less corrosion resistant.
Choosing 2304 for a harsh chemical environment
It is lean in molybdenum. For harsh chlorides, 2205 and above.
Equivalents, standards and supply
| EN | 1.4362 |
|---|---|
| DIN | X2CrNiN23-4 |
| ASTM | UNS S32304 |
| Standards | ASTM A240 UNS S32304 / EN 10088-2 |
| Forms | plate · rod · pipe |
| Producers | Outokumpu LDX 2101 · Sandvik SAF 2304 · Valbruna |
Learn more
Values are typical and for comparison only. For design, rely on the standard and on the mill certificate. Sources: ASTM A240, ASTM A276 and EN 10088 (composition), producer data sheets, and the METAL HUB materials database.
Updated: October 31, 2026