Stainless Steel 17-6PH
AISI/SAE 17-6PH · UNS S17600 · also Alloy 635
17-6PH (S17600, Alloy 635) is a semi-austenitic Cr17-Ni7-Al precipitation-hardening stainless, similar in class to 17-7PH, used historically for aerospace springs and fasteners that must be formed before final aging.
Reference datasheet — 17-6PH is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the A condition
17-6PH tempers and conditions
17-6PH is supplied in 7 conditions, soft to hard. A is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ADefault Solution annealed | Stock/supply condition: machine, form and cold-head here, then age in one step with minimal distortion. | 760 | 965 | 12 | 30 HRC | — |
Aged 593 °C (1100 °F) for 4 h | Maximum-ductility overaged condition for weldments and parts needing best SCC resistance at ~1000 MPa. | 900 | 1,035 | 15 | 33 HRC | — |
Aged 565 °C (1050 °F) / 4 h, air cool | Overaged, toughest useful strength level — choose for thick sections, impact loading or chloride-bearing service. | 1,035 | 1,140 | 13 | 37 HRC | — |
Cold drawn, Condition A | Cold-drawn spring wire supplied for coiling and subsequent single-step age hardening. | 1,070 | 1,240 | 6 | 40 HRC | 2.1 % IACS |
Aged 540 °C (1000 °F) / 4 h, air cool | Balanced condition: ~1240 MPa with better toughness and stress-corrosion margin than H950. | 1,140 | 1,240 | 11 | 41 HRC | — |
Aged 510 °C (950 °F) / 1–4 h, air cool | High-strength aerospace condition for fasteners, shafts and spring elements with acceptable ductility. | 1,240 | 1,345 | 9 | 44 HRC | — |
Aged 482 °C (900 °F) for 1 h, peak hardness | Peak-strength aging for springs and small fasteners where hardness matters more than toughness or SCC margin. | 1,275 | 1,380 | 8 | 45 HRC | — |
What is 17-6PH?
17-6PH (S17600, Alloy 635) is a semi-austenitic Cr17-Ni7-Al precipitation-hardening stainless, similar in class to 17-7PH, used historically for aerospace springs and fasteners that must be formed before final aging. Condition A material is soft enough to bend, coil and cold head, and the H900 to H1100 tempers develop up to 760 MPa yield, 965 MPa tensile, 12 % elongation and 30 HRC (285 HB) with very little distortion during aging. Limits are a 300 °C service ceiling, corrosion resistance of 55/100 (below 304), reduced aging response in weld metal and restricted mill availability today; 17-7PH (S17700, 1.4568) is the usual current substitute. 17-6PH has a density of 7.8 g/cm³ (0.282 lb/in³), heavier than 50% of stainless steel grades. It melts at 1,400°C (2,552 °F). 17-6PH has a yield strength of 760 MPa (110 ksi) and a tensile strength of 965 MPa (140 ksi) — stronger than 94% of stainless steel grades. Elongation at break is 12% and the elastic modulus is 200 GPa (29 Msi).
What is 17-6PH used for?
- springs
- fasteners
- aerospace structural clips
Advantages
- High strength — 760 MPa (110 ksi), better than 94% of stainless steel grades
Limitations
- Limited ductility — 12%, worse than 95% of stainless steel grades
- Limited service temperature — 300°C (572 °F), worse than 90% of stainless steel grades
- Difficult to weld — 45/100, worse than 79% of stainless steel grades
17-6PH properties
Typical room-temperature values for 17-6PH-A; bars are the position among stainless steel grades.
Physical3
17-6PH has a density of 7.8 g/cm³ (0.282 lb/in³), heavier than 50% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical14
17-6PH has a yield strength of 760 MPa (110 ksi) and a tensile strength of 965 MPa (140 ksi) — stronger than 94% of stainless steel grades. Elongation at break is 12% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
17-6PH is rated for continuous service to 300°C (572 °F). It conducts heat at 16 W/m·K (9.24 BTU/hr·ft·°F), better than 58% of stainless steel grades. Thermal expansion is 10.8 µm/m·K (6 µin/in·°F).
Electrical3
17-6PH conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 71% of stainless steel grades.
Sustainability4
Producing a kilogram of 17-6PH takes about 56 MJ of energy and emits 5 kg of CO₂ — more than 59% of stainless steel grades. Typical recycled content is 35%.
Manufacturability7
17-6PH's machinability is fair (38/100, better than 63% of stainless steel grades); weldability fair (45/100); formability fair (45/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. 17-6PH is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 17-6PH
Is 17-6PH easy to machine?
Machine in Condition A with rigid setups, sharp positive-rake carbide, heavy positive feeds and flood coolant; the alloy work-hardens quickly, so avoid dwelling and expect ~40 % of 1212 rates (drop to ~25 % after H950 aging).
Can 17-6PH be welded?
GTAW/GMAW/EBW with matching or 17-4PH filler is possible, but the Ti-bearing weld metal loses much of its aging response — post-weld solution treat plus re-age wherever full properties are required.
Can 17-6PH be formed, bent or molded?
Cold form, bend, coil or cold-head only in Condition A; aging causes very little distortion or size change, so form to near-net shape first and age last.
17-6PH chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| C | ≤ 0.08 | 0.06 |
| Mn | ≤ 1 | 0.5 |
| Si | ≤ 1 | 0.5 |
| P | ≤ 0.04 | |
| S | ≤ 0.03 | |
| Cr | 16 – 17.5 | 16.75 |
| Ni | 6 – 7.5 | 6.8 |
| Tiprimary age-hardening element (Ni3Ti) | 0.4 – 1.2 | 0.75 |
| Al | ≤ 0.4 | 0.2 |
| Fe | balance |
What surface finishes work on 17-6PH?
Passivate per ASTM A967 (nitric or citric) after machining; electropolishing improves pitting resistance, and shot peening after aging restores fatigue life — plate only with baking at 190 °C to avoid hydrogen embrittlement.
Surface treatments FabDigit runs on stainless steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Passivation
Organic Coating
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Stainless Steel 17-6PH in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- S17600
- Trade names
- Alloy 635
How much does 17-6PH cost?
17-6PH is a high-cost stainless steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
17-6PH — frequently asked
What is 17-6PH used for?
17-6PH is typically used for springs, fasteners and aerospace structural clips. In short: forms soft, ages hard; low distortion on aging; limited mill availability.
What is the yield strength of 17-6PH?
17-6PH has a typical yield strength of 760 MPa (110 ksi) and a tensile strength of 965 MPa (140 ksi) — stronger than 94% of stainless steel grades. Strength varies by condition: see the 7 listed tempers.
Is 17-6PH easy to machine?
Not especially — machinability is rated fair (38/100, better than 63% of stainless steel grades). Machine in Condition A with rigid setups, sharp positive-rake carbide, heavy positive feeds and flood coolant; the alloy work-hardens quickly, so avoid dwelling and expect ~40 % of 1212 rates (drop to ~25 % after H950 aging).
Can 17-6PH be welded?
With care — weldability is rated fair (45/100). GTAW/GMAW/EBW with matching or 17-4PH filler is possible, but the Ti-bearing weld metal loses much of its aging response — post-weld solution treat plus re-age wherever full properties are required.
What surface finishes work on 17-6PH?
Passivate per ASTM A967 (nitric or citric) after machining; electropolishing improves pitting resistance, and shot peening after aging restores fatigue life — plate only with baking at 190 °C to avoid hydrogen embrittlement.
Can 17-6PH be formed, bent or molded?
Cold form, bend, coil or cold-head only in Condition A; aging causes very little distortion or size change, so form to near-net shape first and age last.
What is the maximum service temperature of 17-6PH?
17-6PH is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 17-6PH-A and 17-6PH-H900?
A is the default condition — stock/supply condition: machine, form and cold-head here, then age in one step with minimal distortion. H900: peak-strength aging for springs and small fasteners where hardness matters more than toughness or SCC margin. Yield strength is 760 MPa in A versus 1,275 MPa in H900.
How much does 17-6PH cost?
17-6PH is a high-cost stainless steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASM Handbook Vol. 1: Properties and Selection — Irons, Steels and High-Performance Alloys (precipitation-hardening stainless steels) — ASM International (1990)
- SAE AMS 5638 / UNS S17600 — Stainless W (Type 635) chemistry and heat treatment — SAE International (2018)
- ASM Handbook Vol. 13B: Corrosion — Materials (stainless steel corrosion behaviour) — ASM International (2005)
- ASTM A967 — Chemical Passivation Treatments for Stainless Steel Parts — ASTM International (2017)
- MMPDS-style typical room-temperature property tables for PH stainless steels — Battelle / FAA (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.