316L
1.4404 · EN 10088 / AISI · 1.4404
316L is a stainless steel (Austenitic family) to EN 10088 / AISI (1.4404). It has a specified 0.2 % proof stress of 200 MPa and a typical tensile strength of about 500 MPa, with a uniform elongation of 40 %. For nonlinear FEA, a bilinear model uses E = 193 GPa up to yield and a tangent modulus of 756 MPa above it. Its austenitic structure gives excellent corrosion resistance, formability and cryogenic toughness, but it cannot be hardened by heat treatment.
Bilinear material model — nonlinear FEA
Uniform elongation εu = 40.0% · conservative analysis limit ½εu = 20.0%
Bilinear (BISO) approximation. Elastic modulus E up to the 0.2% proof stress R_p0.2, then a single tangent slope Eₜ to the ultimate tensile strength: Eₜ = (Rₘ − R_p0.2) / (εu − R_p0.2/E − 0.002), where εu is the uniform elongation and Rₘ is a typical (nominal) UTS within the specified band. The half-εu figure is a conservative strain limit for the analysis. Treat these as guidance for first-pass models; for critical work use a measured true stress–strain curve for the actual product and condition.
Ratings — engineering judgement
Weldabilityexcellent
The reason 316L exists — the ≤ 0.03 % carbon prevents chromium-carbide sensitisation in the HAZ, so it welds without the intergranular-corrosion risk of standard 316. Use 316L filler; no preheat.
Formabilitygood
Excellent cold formability like all austenitics; work hardens strongly, so allow for force and spring-back.
Machinabilitypoor
Work-hardens rapidly — sharp carbide tooling, positive rake, firm feeds, flood coolant. Slightly worse than 304.
Corrosion resistanceexcellent
Same excellent pitting/crevice resistance as 316 from the 2–2.5 % Mo, with the added assurance that welds stay corrosion-resistant. The default for welded marine and chemical service.
Hardenabilitynone
Not hardenable by heat treatment; strengthen only by cold work.
Toughnessexcellent
Outstanding at all temperatures including cryogenic; no ductile-to-brittle transition.
Expert notes
316L is simply 316 with the carbon held down to ≤ 0.03 %. In practice it has become the default whenever 316 is welded, which is most of the time — so much stock is dual-certified as 316/316L that you often get both in one bar.
The reason is weld decay: standard 316 heated through ~450–850 °C (as any weld HAZ is) can precipitate chromium carbides at grain boundaries, locally stripping corrosion resistance. Low carbon stops that. If your 316 part sees a welding arc, specify 316L.
The trade-off is a small drop in room-temperature strength (the L grades have slightly lower minimum proof stress). For almost all applications that is irrelevant; where it isn’t, look at 316Ti (titanium-stabilised) or a higher grade rather than accepting standard 316 in a welded joint.
Everything else about 316 applies — marine-grade chloride resistance, austenitic toughness and formability, galling-prone threads (use anti-seize), and A4 fastener class.
Mechanical properties
| Condition | Section | Yield (MPa) |
|---|---|---|
| 316L · solution annealed | t ≤ 75 mm | 200 |
UTS 500–700 MPa · Impact ≥ 60 J @ 20 °C (often >150 J) · Hardness ≤ 215 HB
Physical properties
| Density | 7990 | kg/m³ |
| Elastic modulus | 193 | GPa |
| Shear modulus | 74 | GPa |
| Poisson's ratio | 0.30 | |
| Thermal expansion | 15.9 | ×10⁻⁶/°C |
| Thermal conductivity | 15 | W/(m·K) |
| Specific heat | 500 | J/(kg·K) |
| Magnetic | No (annealed) |
Chemical composition (wt %)
Available forms
Equivalent grades
| Standard | Grade | Note |
|---|---|---|
| EN 10088 | X2CrNiMo17-12-2 / 1.4404 | |
| AISI | 316L | |
| BS 970 Pt 4 | 316S11 | |
| JIS | SUS316L | |
| UNS | S31603 |
Historical designations
| Standard | Grade | Note |
|---|---|---|
| BS 970:1970 Pt 4 | 316S11 | British low-carbon 316 designation. |
| Werkstoff Nr. | 1.4404 | German material number. |
Common applications
- Welded chemical and pharmaceutical vessels and pipework
- Marine and coastal fabrications
- Food and hygienic process equipment
- Surgical implants and instruments
- Heat exchangers and tanks
- Fasteners for corrosive service (A4 class)
History
The low-carbon “L” grades were introduced in the mid-20th century once weld sensitisation was understood — dropping carbon below ~0.03 % keeps chromium in solution and preserves corrosion resistance across the weld.
- 1930Molybdenum-bearing 316 developed for chloride service
- 1960Low-carbon “L” grades introduced to solve weld-decay in fabricated stainless
- 1970316L becomes the default specification for welded 316 fabrication