317 Stainless Steel
317 is a molybdenum-bearing austenitic stainless steel designed for stronger resistance in aggressive media. Compared with 316, it typically carries higher molybdenum and nickel, which can provide better performance in certain acids and improved resistance to pitting and crevice corrosion in chloride exposure.
In today’s market, many projects specify 317L for welded fabrication. 317 can still be used when the standard allows it, but the welding plan and corrosion risk in the heat-affected zone should be reviewed carefully.
Alloy focus
Higher Mo and Ni
Stronger resistance in some acids and chloride exposure.
Typical equivalents
EN 1.4449 / SUS317
Use the governing project standard for ordering.
Oxidation resistance
Up to ~870°C
Service limits depend on design code and duty cycle.
Magnetism
Non-magnetic (annealed)
Slight magnetism may appear after cold work.
317 is often selected for chemical handling and marine or coastal environments where corrosion margin is critical. It is used in process equipment that sees acids, chlorides, or both, especially when long service life is required.
- Chemical and petrochemical: evaporators, heat exchangers, reactors, and aggressive piping
- Marine and coastal: offshore piping, condensers, pump and valve components
- Pulp and paper: digesters, bleaching vessels, and related process lines
- Pollution control: scrubbers and absorption towers
- Food processing: tanks and acid-resistant parts where specified
317 may appear under different naming systems. Equivalents are helpful for cross-reference, but the purchase order should be written to the target standard and product form.
| System | Designation | Note |
|---|---|---|
| ASTM / AISI | 317 | Common U.S. grade name |
| JIS | SUS317 | Japanese designation |
| UNS | S31700 | Used for material identification and MTC |
| EN | 1.4449 | European equivalent often referenced in projects |
| DIN | X5CrNiMo18-12-3 | Common German format naming |
| GOST / GB | 03Х17Н14М3 / 0Cr18Ni12Mo3 | Regional equivalents used in documentation |
- Corrosion resistance: typically stronger than 316 in sulfuric and acetic acid service, with improved localized corrosion resistance in chloride exposure.
- Strength and stability: good mechanical strength and stable performance under pressure.
- Heat performance: good oxidation resistance up to about 870°C in appropriate service conditions.
- Magnetism: non-magnetic in annealed condition, useful where non-magnetic behavior is requested.
Values below are typical specification limits used in many orders. Always confirm the final delivered chemistry on the Mill Test Certificate.
| Element | Typical limit / range | Role |
|---|---|---|
| C | ≤ 0.08% | Controls sensitization risk and weld behavior |
| Cr | 18.0–20.0% | Base corrosion resistance and passivation |
| Ni | 11.0–15.0% | Toughness and austenitic structure stability |
| Mo | 3.0–4.0% | Improves pitting/crevice resistance and acid performance |
| Mn / Si | Mn ≤ 2.0%, Si ≤ 1.0% | Supports processing and deoxidation control |
| P / S | P ≤ 0.045%, S ≤ 0.03% | Impurity control for quality and performance |
| Fe | Balance | Base metal |
Properties vary by product form and thickness. For design work, use code tables and the governing specification.
| Property | Typical value | Note |
|---|---|---|
| Tensile strength | ≥ 515 MPa | Reference for annealed condition |
| Yield strength (0.2%) | ≥ 205 MPa | Reference for annealed condition |
| Elongation | ≥ 40% | Supports forming and fabrication |
| Hardness | ≤ 217 HBW | Typical maximum in specification |
317 can be supplied in a wide range of industrial forms. Availability depends on requested tolerances, finish, and inspection scope. If you share your standard, size, quantity, and destination, LYH Steel can advise the best supply route.
| Form | Typical size range | Notes |
|---|---|---|
| Sheet (cold rolled) | Thickness 0.3–6.0 mm, width 1000–2000 mm | Common for fabrication and cladding |
| Plate (hot rolled) | Thickness 3–100 mm, width 1000–2000 mm | Used for pressure parts and heavy equipment |
| Coil (cold rolled) | Thickness 0.3–6.0 mm, width 1000–2000 mm | Slitting and cut-to-length available |
| Coil (hot rolled) | Thickness 3–14 mm, width 1000–2000 mm | For thicker and structural applications |
| Strip | Width 7–600 mm, thickness 0.3–10 mm | Often used in fabrication and parts production |
| Pipe / tube | Seamless and welded options (OD/WT per standard) | Specify NDT, hydrotest, and surface requirements |
| Bars and shapes | Round/flat/angle/channel (size per request) | Common for machining and frames |
- Machining: similar to 316; stable results typically require slower speeds, sharp tooling, and proper coolant.
- Welding: control heat input and keep weld procedures disciplined. In corrosive service, post-weld treatment may be required depending on project rules.
- Forming: generally suitable for standard cold forming and bending with proper radius and tooling.
- Heat treatment: solution anneal is commonly used for best corrosion performance, followed by rapid cooling.
- Finishing: compatible with pickling, passivation, and polishing when specified.
317 and 317L are close in corrosion performance, but 317L is often preferred in modern projects because the lower carbon level helps reduce sensitization risk in welded zones. This can improve long-term reliability and simplify fabrication planning.
| Topic | 317 | 317L |
|---|---|---|
| Carbon limit | Higher (typical spec limit ≤ 0.08%) | Lower (often specified for welding stability) |
| Welded fabrication | More attention required to sensitization control | Common choice for welded equipment |
| Current availability | Less common in many supply chains | More common for industrial projects |
Use these internal tools to confirm equivalents, estimate weight, and plan tolerances before you issue an RFQ.
Is 317 stainless steel still used today?
Yes, but it is less common in many supply chains. For welded equipment and long-term corrosion control, many projects choose 317L as the modern alternative.
What is the main advantage of 317 over 316?
317 typically includes higher molybdenum and nickel, which can improve resistance in certain acids and increase pitting and crevice corrosion resistance in chloride exposure.
Is 317 stainless steel magnetic?
In the annealed condition, it is generally non-magnetic. Slight magnetism can appear after cold working.
When should I consider 317L instead of 317?
If the fabrication involves welding, heat-affected zones, and aggressive chloride service, 317L is commonly preferred because the low carbon level helps reduce sensitization risk and improves long-term stability.
