17-4 PH vs 316L Stainless Steel
Side-by-side comparison · Composition · Properties · Selection guide
17-4 PH and 316L solve different engineering problems. Aged 17-4 PH provides several times the yield strength of annealed 316L for shafts, valve parts and loaded components, while 316L provides better general corrosion resistance, weldability and low-temperature toughness for vessels, piping and fabricated equipment.
Full datasheets:17-4 PH Stainless Steel·316L Stainless Steel
At a Glance
| 17-4 PH | 316L | |
|---|---|---|
| Type | Precipitation hardening (martensitic) | Austenitic (low carbon, Mo-bearing) |
| UNS | S17400 | S31603 |
| Standard | ASTM A564/A564M | ASTM A240/A240M |
| Density | 7.75 g/cm³ | 7.98 g/cm³ |
Corrosion Resistance and Service Limits
17-4 PH
- Corrosion resistance can approach 304 in atmospheric and fresh-water service in suitable conditions but does not make this grade a substitute for 316 in chloride exposure.
- Ageing condition, stress, surface finish, crevices and chloride level must be reviewed together, especially for highly stressed or peak-aged components.
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.
Fabrication and Heat Treatment
| Operation | 17-4 PH | 316L |
|---|---|---|
| Welding | Weld in the solution-treated condition where practical, then apply the specified post-weld solution and ageing route when joint properties require it. | Generally weldable with a qualified procedure and matching or over-alloyed filler where required; remove heat tint when corrosion service demands it. |
| Forming | Form in solution-treated condition and account for high strength, springback and dimensional change during subsequent ageing. | Good ductility is typical, but rapid work hardening increases forming load and springback; bend radius and intermediate annealing depend on grade and reduction. |
| Machining | Machine in solution-treated or over-aged condition according to the dimensional and strength plan; final ageing can change size and hardness. | Use rigid tooling, positive feeds and controlled heat because the material work-hardens; free-machining grades require separate corrosion and welding review. |
| Heat treatment | Condition A solution treatment followed by the ordered H ageing condition controls the strength-toughness balance. The exact condition is a mandatory purchase-order field. | 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 | 17-4 PH | 316L |
|---|---|---|
| C | ≤0.07 | ≤0.030 |
| Mn | ≤1.00 | ≤2.00 |
| Si | ≤1.00 | ≤0.75 |
| Cr | 15.0–17.5 | 16.0–18.0 |
| Ni | 3.0–5.0 | 10.0–14.0 |
| Cu | 3.0–5.0 | — |
| Nb | 0.15–0.45 | — |
| P | ≤0.040 | ≤0.045 |
| S | ≤0.030 | ≤0.030 |
| Mo | — | 2.00–3.00 |
Mechanical Properties
| Property | 17-4 PH | 316L |
|---|---|---|
| Tensile strength (H900) | ≥1310 MPa (190 ksi) | — |
| Yield strength (H900) | ≥1170 MPa (170 ksi) | — |
| Elongation (H900) | ≥10% | — |
| Tensile strength (H1150) | ≥930 MPa (135 ksi) | — |
| Hardness (Condition A) | ≤363 HBW | — |
| Tensile strength | — | ≥485 MPa (70 ksi) |
| Yield strength (0.2%) | — | ≥170 MPa (25 ksi) |
| Elongation (50 mm) | — | ≥40% |
| Hardness | — | ≤217 HBW |
Which One Should You Choose?
Choose 17-4 PH for:
- High-strength shafts, stems and mechanical parts
- Components needing an age-hardening response
- Machined parts where section size must stay compact
- Moderately corrosive service with controlled heat treatment
Choose 316L for:
- Welded tanks, pipe and sheet fabrication
- Marine, food and chemical exposure
- Cryogenic or impact-sensitive service
- Parts needing high ductility without post-fabrication aging
Our verdict
Choose 17-4 PH when load, wear and compact section size drive the design and a defined aging condition can be maintained. Choose 316L when corrosion, welding, forming or low-temperature toughness dominates. They are not grade-for-grade substitutes even when both appear on a stainless material list.
Cost and Availability
Compare the current stock position, mill route, minimum production quantity, processing yield, testing and delivered cost for 17-4 PH and 316L 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 17-4 PH with 316L, 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.
17-4 PH & 316L 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 17-4 PH more corrosion resistant than 316L?
No. 17-4 PH has useful atmospheric and mild-process resistance, but molybdenum-bearing 316L usually performs better in chloride and many chemical environments.
What condition should 17-4 PH be ordered in?
State Condition A for later aging or a specific aged condition such as H900, H1025 or H1150. Each condition changes strength, toughness and stress-corrosion behavior.
Can 17-4 PH be welded like 316L?
No. It can be welded with suitable procedures, but filler choice and post-weld aging must be coordinated with the required final properties.
RFQ
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Technical content updated: 2026-07-29
Organizational author: Tsingshan (Shandong) Iron & Steel Co., Ltd..Review method, status and limitations.