Last verified 19 August 2026.
The comparison
| Property | 316L | 444 | Evidence |
|---|---|---|---|
| Proof strength Rp0.2, minimum (EN) | 240 MPa | 300 MPa | E3 E3 |
| Tensile strength Rm, minimum | 530 MPa | 420 MPa | E3 E3 |
| PREN | 24 — | 25 — | E3 E3 |
| Modulus of elasticity | 200 GPa | 220 GPa | E3 E3 |
| Density | 8.0 g/cm³ | 7.7 g/cm³ | E3 E3 |
| Thermal conductivity | 15 W/(m·K) | 23 W/(m·K) | E3 E3 |
| Proof strength Rp0.2, minimum | 170 MPa | not established here | E3 / — |
| Elongation, minimum | 40 % | not established here | E3 / — |
All shared rows compare like for like.
The trap on this comparison
Proof strength Rp0.2 is specified twice: 170 MPa (ASTM A240/A240M, plate, annealed, 20 °C) and 240 MPa (EN 10088-2, cold rolled coil and sheet, 20 °C) — 41% apart. Both correct. Which one governs is a question about your drawing and your product form, not about the material.
Where each side’s numbers come from
See 316L and 444 — 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
316L. It is the default molybdenum-bearing austenitic, and the reasons are practical rather than exceptional. Single phase, so no phase balance to manage in welding. Forgiving heat input. Formable. Stocked by everyone in every product form. Every fabricator has qualified procedures for it. When a design is not strength-driven and the environment is not aggressive, 316L is chosen because choosing anything else has to be justified.
444. Hot water tanks, heat exchangers and process equipment in mild chlorides where nickel price volatility is the problem being solved. It sits at the pitting ranking of 316L without nickel, conducts heat better, expands less and does not suffer chloride stress corrosion cracking — which for a hot water application is the failure mode that actually occurs.
Against 316L: Two things. Strength: at the 170 MPa ASTM A240 plate minimum it is weak for a structural section, and a strength-driven part in 316L is thick. Chlorides: the molybdenum helps against pitting relative to 304, but 316L is marginal in warm chloride service, and the failure mode that usually appears is crevice corrosion at gaskets and joints, which PREN does not predict.
Against 444: Anything that has to be formed hard, welded thick, or stay tough cold. Elongation is not even quoted on the row consulted, weld zones lose toughness, and the transition temperature makes heavy section a bad idea. It is also thinly stocked compared with 316L, so a substitution that works on paper often fails on lead time.
What this comparison does not cover
- Composition limits are not established, and they are what a purchase order actually specifies.
- Elevated and cryogenic temperature behaviour.
- Fatigue, fracture toughness and stress corrosion cracking.
- Welding procedure guidance, filler selection and post-weld treatment.
- Product forms other than plate, where minima differ.
- Whether 316L suits your application. No page can answer that.
- Elongation is not established here for any product form, and that is the property that decides whether a part can be made.
- Impact toughness and the transition temperature are not established here.
- Whether 444 substitutes for 316L in your service. The pitting ranking numbers are close; the failure modes are not the same.
- Welding procedure guidance and filler selection.
- Composition limits, not established.
Generated from data/materials/316l.yaml and 444.yaml.