Stainless 317L · UNS S31703 · W. Nr. 1.4438
Stainless 317L (S31703): composition, properties, fittings and flanges
Stainless 317L (S31703, W. Nr. 1.4438) is High-molybdenum low-carbon austenitic stainless steel. Stainless 317L is specified at Chromium 18.0 - 20.0, Nickel 11.0 - 15.0, Molybdenum 3.00 - 4.00. 317L raises molybdenum to 3 - 4 % and chromium to 19 %, giving a PREN near 30 for the condensers, scrubbers and paper mill duties where…
- UNS
- S31703
- W. Nr.
- 1.4438
- Density
- 8.00 g/cm³ (0.289 lb/in³)
- Key strength
- 515 MPa / 75 ksi
Identification and standards
| Short form | Stainless 317L · UNS S31703 · W. Nr. 1.4438 |
|---|---|
| Classification | High-molybdenum low-carbon austenitic stainless steel |
| UNS | S31703 |
| Werkstoff number | 1.4438 |
| Material family | Stainless Steel |
Chemical composition
| Element | Composition (wt %) | Why it is there |
|---|---|---|
| Chromium (Cr) | 18.0 - 20.0 | Passive film |
| Nickel (Ni) | 11.0 - 15.0 | Austenite stability |
| Molybdenum (Mo) | 3.00 - 4.00 | Pitting and crevice resistance |
| Carbon (C) | 0.030 max | Weldability |
| 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) | 515 MPa / 75 ksi |
|---|---|
| 0.2 % yield strength, min | 205 MPa / 30 ksi |
| Elongation in 2 in, min | 40 % |
| Typical hardness, annealed | 145 - 190 HB |
| PREN, typical | About 30 |
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 | 1370 - 1400 °C (2500 - 2550 °F) |
| Modulus of elasticity | 193 GPa (28.0 x 10⁶ psi) |
| Thermal conductivity at 20 °C | 16.0 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 F317L · ASME SA-182 |
|---|---|
| Butt weld fittings | ASTM A403 WP317L · ASME SA-403 |
| Seamless pipe & tube | ASTM A312 TP317L · ASME SA-312 |
| Plate / sheet / strip | ASTM A240 317L · ASME SA-240 |
| Bar / rod | ASTM A276 / A479 |
| Welding consumables | ER317L |
| UNS / EN / China | UNS S31703 · W. Nr. 1.4438 · GB 022Cr19Ni13Mo3 |
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
- Flue gas desulphurisation absorbers and outlet ducting
- Pulp and paper bleach plant washers and piping
- Condenser and heat exchanger tubing in brackish water
- Chemical process vessels handling chlorides and acids
Welding, forming and machining
- Welding
- Weld with ER317L filler. Higher alloyed weld metal offsets segregation and keeps the pitting resistance of the joint close to the parent metal.
- Heat treatment
- Solution anneal at 1010 - 1120 °C and water quench.
- 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 317L 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.