Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
A286 vs 17-4 PH — Selection Guide for Precipitation-Hardening Steel
A286 vs 17-4 PH is the canonical comparison between an iron-nickel-chromium superalloy and a martensitic precipitation-hardening stainless steel. Both are precipitation-hardenable but the metallurgy differs fundamentally: A286 is austenitic FCC + non-magnetic + retains strength to 700 °C; 17-4 PH is martensitic + magnetic + limited to ~315 °C continuous service. This page provides a side-by-side comparison covering chemistry, mechanical properties, magnetic behaviour, cost, and selection criteria. Quick answer: A286 wins for service > 315 °C OR non-magnetic requirement; 17-4 PH wins for ambient-temperature high-strength applications at lower cost (~50 % of A286). See parent A286 stainless steel, related A286 vs Inconel 718, A286 vs Waspaloy, A286 vs Nimonic 80A.
About A286 (UNS S66286)
A286 (UNS S66286) is an iron-nickel-chromium precipitation-hardening austenitic stainless steel — composition 53 Fe-25 Ni-15 Cr-2 Ti-1.3 Mo. Heat-treated to 895 MPa tensile, 655 MPa yield. Service temperature -196 °C to ~700 °C. Non-magnetic (permeability < 1.005). Covered by ASTM A453 grade 660, AMS 5525-5895. Used in jet-engine bolting, gas-turbine combustor hardware, automotive turbocharger, oil & gas downhole, and cryogenic LNG / hydrogen applications.
About 17-4 PH (UNS S17400)
17-4 PH (UNS S17400) is a martensitic precipitation-hardening stainless steel — composition 73 Fe-16 Cr-4 Ni-4 Cu-0.4 Nb. Heat-treated to 1310 MPa tensile (H900 condition), 1170 MPa yield. Service temperature ≤ 315 °C continuous (above this, the precipitation hardness reverts). Magnetic (~ 90 % saturation at 1.5 T). Covered by AMS 5643 / 5604 / 5622, ASTM A564 grade 630. Used in aerospace structural components, valve trim, marine shafts, food-processing machinery, and tooling — wherever ambient-temperature corrosion-resistance + high-strength + cost-efficiency combine.
A286 vs 17-4 PH — Selection Guide for Precipitation-Hardening Steel — Side-by-Side Comparison
| Property | A286 (UNS S66286) | 17-4 PH (UNS S17400) | Notes |
|---|---|---|---|
| Base composition | Fe-Ni-Cr (austenitic) | Fe-Cr-Ni (martensitic) | Different microstructures |
| Density (g/cm³) | 7.94 | 7.80 | 17-4 PH ~2 % lighter |
| Yield strength (MPa) RT | ≥ 655 | ≥ 1170 (H900) | 17-4 PH ~78 % higher yield |
| Tensile strength (MPa) RT | ≥ 895 | ≥ 1310 (H900) | 17-4 PH ~46 % higher tensile |
| Service temperature max (°C) | ~700 (continuous) | ~315 (continuous) | A286 retains strength to 2× the temperature |
| Oxidation resistance max (°C) | 982 | ~430 | A286 superior oxidation |
| Magnetic | No (permeability < 1.005) | Yes (martensitic) | Critical differentiator for instrumentation |
| Hardness (typical) | 29-32 HRC | 40-44 HRC (H900) | 17-4 PH harder; A286 easier to machine |
| Modulus of elasticity (GPa) | 199 | 200 | Essentially identical |
| Thermal expansion (µm/m·°C 20-300 °C) | 17.0 | 10.8 | 17-4 PH lower expansion |
| Cost relative | 1.0× | 0.4-0.5× | 17-4 PH ~50 % cheaper |
| Weldability | Good (post-weld sol-treat needed) | Limited (martensitic) | A286 better for welded fabrication |
| NACE MR0175 compliance | Yes (≤ HRC 35) | Yes (≤ HRC 33) | Both with hardness limits |
| Cryogenic toughness | 85 % at -196 °C | Embrittles at -100 °C | A286 superior cryogenic |
| Best for | ≥ 315 °C OR non-magnetic | Ambient temp + high strength + cost | Choose by service temp + magnetic req |
When to Choose Each Alloy
- Choose A286 when: Service temperature > 315 °C OR application requires non-magnetic material OR cryogenic toughness required. A286 is the only choice for jet-engine, gas-turbine, MRI hardware, magnetometer applications.
- Choose 17-4 PH when: Service temperature ≤ 315 °C AND non-magnetic NOT required AND high tensile strength (> 1170 MPa yield) is required. 17-4 PH is ~50 % the cost of A286 and provides 78 % higher yield strength at room temperature.
- Both alloys are equivalent when: Service temperature ≤ 315 °C AND moderate strength requirement. 17-4 PH is preferred by default — same corrosion performance at half the cost. Use A286 only when temperature, magnetic, or cryogenic requirements drive the choice.
- Above 315 °C service: A286 only — 17-4 PH precipitation hardness reverts above 315 °C, losing strength. For high-temperature applications A286 is the appropriate choice.
- Magnetic-isolation requirement: A286 only — 17-4 PH is magnetic. Critical for instrumentation, MRI, magnetometer, particle-accelerator, and aerospace electromagnetic-sensitive applications.
Applications by Industry
- Aerospace airframe structural: 17-4 PH for low-temperature airframe structural components (fittings, brackets) — high strength + corrosion resistance + cost-effective. A286 reserved for engine and high-temp applications.
- Marine shafts & valves: 17-4 PH dominates marine valve stems, pump shafts, propeller shafts in saltwater + ambient-temperature service. A286 only for marine gas-turbine hot-section bolting.
- Food-processing equipment: 17-4 PH for food-grade valves, pump shafts, agitators where 304/316 stainless lacks strength. A286 over-spec for food-processing.
- Tooling & molds: 17-4 PH for plastic-injection-mold cores, die-casting dies, plastic-extrusion screws — high strength + dimensional stability. A286 unnecessary at these temperatures.
- Aerospace engine bolting: A286 dominates for jet-engine and gas-turbine bolting (540-700 °C service). 17-4 PH used only for cold-section structural bolting.
- MRI / magnetometer hardware: A286 only — 17-4 PH magnetic and would interfere with magnetic flux. Permeability < 1.005 is critical for these applications.
A286 vs 17-4 PH — Selection Guide for Precipitation-Hardening Steel — Frequently Asked Questions
What's the main difference between A286 and 17-4 PH?
A286 is austenitic + non-magnetic + service to 700 °C. 17-4 PH is martensitic + magnetic + service ≤ 315 °C. Different microstructures dictate fundamentally different applications.
Why is 17-4 PH limited to 315 °C?
Above 315 °C the martensitic precipitation hardness reverts (over-aging) — the alloy loses its high-strength condition. A286 austenitic gamma-prime precipitation is stable to ~700 °C. For service temperatures > 315 °C, A286 (or Inconel 718, Waspaloy) is required.
Which is harder, A286 or 17-4 PH?
17-4 PH is harder: typical 40-44 HRC in H900 condition vs A286 at 29-32 HRC. 17-4 PH machining is more difficult; A286 easier to machine but requires anti-galling lubricant.
Is 17-4 PH magnetic?
Yes — martensitic structure is ferromagnetic, ~90 % saturation at 1.5 T. A286 austenitic is non-magnetic (permeability < 1.005). For instrumentation and MRI applications, A286 is the only acceptable choice.
Cost comparison: A286 vs 17-4 PH?
17-4 PH is ~50 % the cost of A286 — A286 raw material ~$8-15/kg vs 17-4 PH ~$5-8/kg depending on form and quantity. The cost difference compounds for high-volume fasteners and structural components.
Can A286 replace 17-4 PH?
Functionally yes — A286 has equivalent or better corrosion resistance and is non-magnetic. But A286 has lower yield strength (655 vs 1170 MPa) at room temperature, so over-design is required if A286 substitutes 17-4 PH on a high-strength application.
Can 17-4 PH replace A286?
NOT for service > 315 °C, NOT for magnetic-sensitive applications, NOT for cryogenic service below -100 °C (17-4 PH embrittles). For ambient-temperature high-strength applications without these constraints — yes, at 50 % the cost.
Which alloy for jet-engine compressor casing?
A286 — service temperature 540-700 °C eliminates 17-4 PH from consideration. 17-4 PH would lose strength at compressor operating temperatures.
Which alloy for marine valve stem?
17-4 PH dominates for ambient-temperature seawater valve stems — high strength + corrosion + cost-effective. A286 only for high-temperature marine gas-turbine valves where 17-4 PH would not retain hardness.
Related Comparisons & A286 Reference
Compare A286 against other precipitation-hardening alloys: A286 vs Inconel 718 · A286 vs 17-4 PH · A286 vs Waspaloy · A286 vs Nimonic 80A · A286 equivalent grades cross-reference.
Canonical A286 reference: A286 chemical composition · A286 mechanical properties · A286 heat treatment · A286 machinability · AMS / ASTM specifications hub.
Satisfaction Survey
