Last verified 19 August 2026.
The comparison
| Property | 2101 | 2304 | Evidence |
|---|---|---|---|
| Proof strength Rp0.2, minimum (EN) | 530 MPa | 450 MPa | E3 E3 |
| Tensile strength Rm, minimum | 700 MPa | 650 MPa | E3 E3 |
| Elongation A, minimum | 30 % | 20 % | E3 E3 |
| PREN | 26 — | 26 — | E3 E3 |
| Density | 7.8 g/cm³ | 7.8 g/cm³ | E3 E3 |
| Modulus of elasticity | 200 GPa | 200 GPa | E3 E3 |
| Thermal conductivity | 15 W/(m·K) | 15 W/(m·K) | E3 E3 |
All shared rows compare like for like.
Where each side’s numbers come from
See 2101 and 2304 — each page lists every source, every demotion and every gap. Nothing on this page is derived from anything not on those two, and our coverage limits are stated separately.
Where a PREN appears above, read it as a ranking number rather than a qualification: what PREN can and cannot tell you.
When to choose which
2101. Structural stainless where the budget is exposed to the nickel price and the environment is mild to moderate. Reinforcement bar, tanks, containers, structural sections and rail vehicle bodies. The strength lets a designer take thickness out, and the lean composition takes the volatility out of what remains.
2304. Structural work in moderate chlorides where the alternative is thick 316L. At roughly double the proof strength, a section designed to yield can be materially thinner, and the material saving usually outruns the price premium. Tanks, bridges, reinforcement and process vessels in brackish rather than sea water are the recurring uses.
Against 2101: Aggressive chlorides and difficult fabrication. At the same pitting ranking as 2304 it is well short of 2205, and nothing about the lean composition changes that. It also work hardens fast, needs more power to form and cut than an austenitic, and demands a controlled welding window like every duplex.
Against 2304: Fabrication discipline and temperature ceiling. Duplex needs a controlled heat input window to keep its phase balance, so procedures have to be qualified and welders have to follow them. And like every duplex it has an upper temperature limit that austenitics do not, which rules it out of hot service entirely.
What this comparison does not cover
- The temperature ceiling is real but not established here as a number.
- Impact toughness and the transition temperature.
- Forming and welding guidance, both of which differ materially from austenitic practice.
- Composition limits, not established.
- Crevice corrosion, which the pitting ranking number does not predict.
- Welding procedure guidance, heat input windows and filler selection.
Generated from data/materials/2101.yaml and 2304.yaml.