316L vs 317L Stainless Steel
Side-by-side comparison · Composition · Properties · Selection guide
317L is 316L with the molybdenum turned up: 3–4% instead of 2–3%, plus a little more chromium and nickel to keep the structure austenitic. Strength, fabrication behavior and weldability are practically identical low-carbon austenitic, so the entire decision rests on corrosion margin — the pitting resistance number (PREN) climbs from roughly 24–26 for 316L to 29–33 for 317L.
Full datasheets:316L Stainless Steel·317L Stainless Steel
At a Glance
| 316L | 317L | |
|---|---|---|
| Type | Austenitic (low carbon, Mo-bearing) | Austenitic (high-Mo, low carbon) |
| UNS | S31603 | S31703 |
| Standard | ASTM A240/A240M | ASTM A240/A240M |
| Density | 7.98 g/cm³ | 7.98 g/cm³ |
Corrosion Resistance and Service Limits
316L
- General corrosion resistance comes from the chromium-rich passive film; nickel, molybdenum, nitrogen and copper change performance by grade.
- Check chlorides, temperature, crevices, deposits, process chemistry and cleaning conditions. A grade designation alone is not a service-life guarantee.
317L
- General corrosion resistance comes from the chromium-rich passive film; nickel, molybdenum, nitrogen and copper change performance by grade.
- Check chlorides, temperature, crevices, deposits, process chemistry and cleaning conditions. A grade designation alone is not a service-life guarantee.
Fabrication and Heat Treatment
| Operation | 316L | 317L |
|---|---|---|
| Welding | Generally weldable with a qualified procedure and matching or over-alloyed filler where required; remove heat tint when corrosion service demands it. | Generally weldable with a qualified procedure and matching or over-alloyed filler where required; remove heat tint when corrosion service demands it. |
| Forming | Good ductility is typical, but rapid work hardening increases forming load and springback; bend radius and intermediate annealing depend on grade and reduction. | Good ductility is typical, but rapid work hardening increases forming load and springback; bend radius and intermediate annealing depend on grade and reduction. |
| Machining | Use rigid tooling, positive feeds and controlled heat because the material work-hardens; free-machining grades require separate corrosion and welding review. | Use rigid tooling, positive feeds and controlled heat because the material work-hardens; free-machining grades require separate corrosion and welding review. |
| Heat treatment | Solution annealing and rapid cooling restore the intended condition where applicable. Austenitic grades are not hardened by conventional quench-and-temper treatment. | Solution annealing and rapid cooling restore the intended condition where applicable. Austenitic grades are not hardened by conventional quench-and-temper treatment. |
Chemical Composition (wt%)
| Element | 316L | 317L |
|---|---|---|
| C | ≤0.030 | ≤0.030 |
| Mn | ≤2.00 | ≤2.00 |
| Si | ≤0.75 | ≤0.75 |
| Cr | 16.0–18.0 | 18.0–20.0 |
| Ni | 10.0–14.0 | 11.0–15.0 |
| Mo | 2.00–3.00 | 3.0–4.0 |
| P | ≤0.045 | ≤0.045 |
| S | ≤0.030 | ≤0.030 |
| N | — | ≤0.10 |
Mechanical Properties
| Property | 316L | 317L |
|---|---|---|
| Tensile strength | ≥485 MPa (70 ksi) | ≥515 MPa (75 ksi) |
| Yield strength (0.2%) | ≥170 MPa (25 ksi) | ≥205 MPa (30 ksi) |
| Elongation (50 mm) | ≥40% | ≥40% |
| Hardness | ≤217 HBW | ≤217 HBW |
Which One Should You Choose?
Choose 316L for:
- General marine, chemical and food-grade duty where 316L has a service record
- Projects driven by price and broad market availability of 316L
- Dual-certified 316/316L supply chains and standard pharma specifications
- Welded fabrication with commodity 316L consumables
Choose 317L for:
- Flue-gas desulfurization scrubbers and ducting
- Pulp bleach washers and chlorine-dioxide environments
- Hot acidic liquors with elevated chloride levels where 316L pits
- Process equipment that has already shown 316L tea-staining or crevice attack
Our verdict
Stay with 316L until service evidence or process chemistry says otherwise — it is generally lower cost, more broadly available, and adequate for many moderate chloride duties. Specify 317L as a targeted option when 316L is marginal, then verify performance against the actual concentration, contaminants and temperature. If conditions are clearly beyond that margin, evaluate duplex 2205 or a 6Mo grade instead.
Cost and Availability
Compare the current stock position, mill route, minimum production quantity, processing yield, testing and delivered cost for 316L and 317L at quotation time. A fixed price ratio would be misleading because product form, size, condition and market timing can change the commercial result.
Do Not Substitute Without Review
Do not replace 316L with 317L, or the reverse, from the grade name alone. Recheck chemistry, mechanical-property condition, product standard, dimensions, corrosion environment, welding procedure and project approval before substitution.
316L & 317L Products We Export
316L Stainless Steel Sheet
316/316L stainless steel sheet for marine and chemical service, in quotation-confirmed dimensions in 2B, BA and brushed finishes, cut to size, with ordered documentation.
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316L Stainless Steel Seamless Pipe
Seamless 316L stainless steel pipe to ASTM A312, in quotation-confirmed NPS and schedule, pickled and annealed, with ordered documentation — for chemical, marine and process service.
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Frequently Asked Questions
Is 317L stronger than 316L?
No — ASTM A240 sets the same minimums for both (515 MPa tensile, 205 MPa yield). The premium buys molybdenum and corrosion margin only. For a strength upgrade with similar corrosion resistance, duplex 2205 is the better value.
How much more does 317L cost?
There is no fixed premium or lead-time rule. Molybdenum content, product form, size, mill route, quantity and testing affect the delivered quotation; compare 317L and 316L for the same specification and procurement date.
Can I weld 317L with 316L filler?
No — the joint would dilute below 317L corrosion performance. Use matching E317L/ER317L consumables, or over-alloyed 309MoL in dissimilar joints. Practice is otherwise the same as welding 316L.
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Technical content updated: 2026-07-29
Organizational author: Tsingshan (Shandong) Iron & Steel Co., Ltd..Review method, status and limitations.