Alloy 316L
Also known as UNS S31603, EN/DIN 1.4404
Alloy 316L is a low-carbon austenitic stainless steel with molybdenum for improved chloride pitting resistance and easy welding.
Alloy 316L (UNS S31603) is a low carbon molybdenum-bearing austenitic stainless steel. The low carbon variant (max 0.03% C) reduces carbide precipitation at grain boundaries during welding, eliminating the risk of intergranular corrosion in the heat-affected zone and enabling use in as-welded condition.
The molybdenum addition (2-3%) provides improved resistance to pitting and crevice corrosion in chloride environments compared to 304 stainless, and good resistance to a wide range of acids and corrosive environments. Listed in NACE MR0175 / ISO 15156 for sour service.
We stock bar in the UK and USA. Plate, tube and fittings are available on enquiry; forgings and castings to order.
- Low carbon content eliminates sensitisation risk in welded condition
- Better pitting and crevice corrosion resistance than 304 stainless
- Good general corrosion resistance in a wide range of environments
- Non-magnetic in the annealed condition
- Listed in NACE MR0175 / ISO 15156 for sour service
| Element | Min | Max |
|---|---|---|
| Iron (Fe) | Bal | |
| Chromium (Cr) | 16.50 | 18.50 |
| Nickel (Ni) | 10.00 | 13.00 |
| Molybdenum (Mo) | 2.00 | 2.50 |
| Manganese (Mn) | - | 2.00 |
| Silicon (Si) | - | 1.00 |
| Carbon (C) | - | 0.030 |
| Phosphorus (P) | - | 0.045 |
| Sulphur (S) | - | 0.030 |
| Nitrogen (N) | - | 0.10 |
| Property | Imperial | Metric |
|---|---|---|
| 0.2% Proof stress (min) | 29.7 ksi | 205 N/mm² |
| Tensile strength (min) | 74.75 ksi | 515 N/mm² |
| Tensile strength (max) | 101.5 ksi | 700 N/mm² |
| Elongation (5.65√S0 & 4D) | 35% | |
| Reduction of area | 40% | |
| Hardness (Brinell) | < 270 | |
| Impact strength (room temp) | Typically > 88 J |
| Property | Imperial | Metric |
|---|---|---|
| 0.2% Proof stress (min) | 29.7 ksi | 205 N/mm² |
| Tensile strength (min) | 74.75 ksi | 515 N/mm² |
| Tensile strength (max) | 101.5 ksi | 700 N/mm² |
| Elongation (5.65√S0 & 4D) | 20% | |
| Reduction of area | 40% | |
| Hardness (Brinell) | < 270 | |
| Impact strength (room temp) | Typically > 88 J |
| Property | Value |
|---|---|
| Density (kg/m³) | 8000 |
| Magnetic permeability (20°C) | < 1.05 |
| Young's modulus (kN/mm²) | 193 |
| Specific electrical resistance, 20°C (µΩ.m) | 0.74 |
| Mean coefficient of thermal expansion, 20-100°C (m/m/°C) | 15.9 x 10⁻⁶ |
| Thermal conductivity, 20°C (W/m.K) | 16.3 |
| Specific heat, 20°C (J/kg.K) | 500 |
Equivalents & cross-references
Standard designations
- UNS
- S31603Unified Numbering System
- EN/DIN
- 1.4404European material number; X2CrNiMo17-12-2
- EN
- X2CrNiMo17-12-2European chemical composition designation
- ASTM
- A479Bar and shapes A276Bar and shapes
- NORSOK
- MDS S01Material data sheet
- NACE
- MR0175 / ISO 15156Sour service
Alloy 316L is also designated UNS S31603, EN/DIN 1.4404, EN X2CrNiMo17-12-2, ASTM A479, ASTM A276, NORSOK MDS S01 and NACE MR0175 / ISO 15156.
Common questions
What is the UNS number for Alloy 316L?
Alloy 316L is an austenitic stainless steel covered by UNS S31603, EN 1.4404 (X2CrNiMo17-12-2), ASTM A479 and ASTM A276, and listed in NACE MR0175/ISO 15156 and NORSOK MDS S01. It is supplied in the hot worked and annealed condition, with molybdenum giving much improved corrosion resistance over Alloy 304 and a Pitting Resistance Equivalent Number (PREN) of 25. Langley Alloys stocks it as bar; plate, tube and fittings are available on enquiry, and forgings and castings are to order.
What is Alloy 316L used for?
Alloy 316L is used for process industry chemical containers, transport units and heat exchangers; marine and shipbuilding piping, pumps, valves, fittings and architecture; oil and gas piping, valves, pumps and heat exchangers; and mining industry woven screens. It is widely used in larger section welded components because the low carbon content makes it immune from grain boundary sensitisation.
How does Alloy 316L compare with Alloy 304?
Alloy 316L has higher resistance to pitting and crevice corrosion in seawater than Alloy 304, with a PREN of 25 compared with 19 for Alloy 304, thanks to its molybdenum addition. It also provides higher creep, stress-to-rupture and tensile strength at elevated temperatures than a basic Alloy 304. As a low carbon version of Alloy 316, it is immune from the sensitisation caused by carbide precipitation at grain boundaries when heated.
What is the difference between 316 and 316L?
Grade 316L (UNS S31603) has a lower maximum carbon content (0.03%) than standard 316 (UNS S31600, max 0.08%). The lower carbon reduces the risk of sensitisation and intergranular corrosion in the heat-affected zone during welding. Langley Alloys stocks 316L to ASTM A479, A276, Norsok MDS S01, and NACE MR0175/ISO 15156.
What is EN 1.4404 stainless steel?
EN 1.4404 (X2CrNiMo17-12-2) is the European designation for UNS S31603, the low-carbon 316L austenitic stainless steel. Langley Alloys stocks this grade as Alloy 316L to ASTM A479, ASTM A276, Norsok MDS S01, and NACE MR0175/ISO 15156.
What is the density of Alloy 316L?
Alloy 316L has a density of approximately 8.00 g/cm³ (8000 kg/m³).
Is Alloy 316L magnetic?
No. Alloy 316L is an austenitic stainless steel and is non-magnetic in the annealed condition (magnetic permeability below 1.05). Heavy cold work can make it slightly magnetic.
Datasheets
Alloy 316L bars are supplied in the solution annealed condition; each bar is ultrasonically tested and visually inspected.
Tools for this grade
Pitting & crevice resistance
Pitting & Crevice Resistance
Rank alloys by PREN and get an indicative pitting temperature for a chloride service. Pick a grade and a service temperature to see whether it has margin against pitting, or compare the range in the table below. A first-pass screen for chloride and seawater service.
| Grade | UNS | PREN | Indicative CPT | Relative pitting resistance |
|---|
Indicative screen, not a certified result. PREN ranks pitting resistance; the pitting temperature here is estimated from PREN (CPT ≈ 2.5 × PREN - 50), consistent with Langley's "PREN >40, CPT exceeding 50°C" for super duplex. Real critical pitting/crevice temperature depends on test method, product form, surface finish and service chemistry. Crevice corrosion starts well below the pitting temperature - allow a margin at gaskets, deposits and flange faces. Use certified data for design.
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