Stainless 316L · UNS S31603 · W. Nr. 1.4404
Stainless 316L (S31603): composition, properties, fittings and flanges
Stainless 316L (S31603, W. Nr. 1.4404) is Low-carbon molybdenum austenitic stainless steel. Stainless 316L is specified at Chromium 16.0 - 18.0, Nickel 10.0 - 14.0, Molybdenum 2.00 - 3.00. 316L is the welding grade: 0.03 % maximum carbon means flanges, elbows and spools can be welded, stress relieved and put into chloride…
- UNS
- S31603
- W. Nr.
- 1.4404
- Density
- 8.00 g/cm³ (0.289 lb/in³)
- Key strength
- 485 MPa / 70 ksi
Identification and standards
| Short form | Stainless 316L · UNS S31603 · W. Nr. 1.4404 |
|---|---|
| Classification | Low-carbon molybdenum austenitic stainless steel |
| UNS | S31603 |
| Werkstoff number | 1.4404 |
| Material family | Stainless Steel |
Chemical composition
| Element | Composition (wt %) | Why it is there |
|---|---|---|
| Chromium (Cr) | 16.0 - 18.0 | Passive film |
| Nickel (Ni) | 10.0 - 14.0 | Austenite stability |
| Molybdenum (Mo) | 2.00 - 3.00 | Pitting and crevice resistance |
| Carbon (C) | 0.030 max | Prevents intergranular corrosion after welding |
| Manganese (Mn) | 2.00 max | - |
| Silicon (Si) | 0.75 max | - |
| Phosphorus (P) | 0.045 max | - |
| Iron (Fe) | Balance | Matrix |
Note Single figures are maximum limits unless shown as a range. Always confirm against the heat-specific EN 10204 3.1 certificate supplied with your order.
Mechanical properties
| Tensile strength, min (annealed) | 485 MPa / 70 ksi |
|---|---|
| 0.2 % yield strength, min | 170 MPa / 25 ksi |
| Elongation in 2 in, min | 40 % |
| Typical hardness, annealed | 140 - 185 HB |
| PREN, typical | About 25 |
Warning Values depend on product form, section thickness and heat treatment. Larger sections generally achieve lower strength than thin product; always design against the applicable code allowable stress rather than these figures.
Physical properties
| Density | 8.00 g/cm³ (0.289 lb/in³) |
|---|---|
| Melting range | 1375 - 1400 °C (2500 - 2550 °F) |
| Modulus of elasticity | 193 GPa (28.0 x 10⁶ psi) |
| Thermal conductivity at 20 °C | 16.3 W/m·K |
| Mean coefficient of thermal expansion, 20-100 °C | 16.5 µm/m·°C |
| Specific heat capacity | 500 J/kg·K |
Specifications by product form
| Forgings & flanges | ASTM A182 F316L · ASME SA-182 |
|---|---|
| Butt weld fittings | ASTM A403 WP316L · ASME SA-403 |
| Seamless pipe & tube | ASTM A312 TP316L · ASME SA-312 |
| Plate / sheet / strip | ASTM A240 316L · ASME SA-240 |
| Bar / rod | ASTM A276 / A479 |
| Welding consumables | ER316L |
| UNS / EN / China | UNS S31603 · W. Nr. 1.4404 · GB 022Cr17Ni12Mo2 |
Product forms available
Hangbo supplies this grade in the following forms. Sizes outside the listed range can often be produced to order.
- Forged flanges blanks and finished flanges to ASME B16.5, B16.47 Series A/B and B16.36
- Butt weld elbows, tees, reducers, caps and stub ends to ASME B16.9 and MSS SP-43
- Seamless pipe and tube to the applicable ASTM / ASME pipe specification
- Forged rings, discs and hubs machined to your drawing
Typical applications
- Welded chemical, marine and pharmaceutical piping
- Offshore utility, seawater and ballast systems
- Semiconductor and high-purity water distribution
- Medical implants and surgical instrumentation
Welding, forming and machining
- Welding
- The most weldable of the common stainless grades. Use ER316L filler, control interpass temperature and avoid prolonged service above 600 °C where sigma phase can form.
- Heat treatment
- Solution anneal at 1010 - 1120 °C and water quench; stress relieve at 815 °C if required.
- Hot and cold forming
- Hot work in the range stated by the mill for this grade, then re-solution or re-age before final machining so that the delivered condition matches the certificate.
- Machining
- Machine with sharp carbide or high-speed steel tooling, positive rake, constant feed and ample coolant. Never dwell - the surface work-hardens quickly.
Buy Stainless 316L from Hangbo
Material is supplied with full heat-number traceability, solution annealing or ageing performed under calibrated furnace control, and an EN 10204 3.1 certificate covering chemical analysis, mechanical properties, heat treatment records and the agreed NDT scope. Positive material identification and third party inspection and test reports from SGS are available for critical service.