Steel SUH660
JIS SUH660
SUH660 is the JIS G 4311 iron-base precipitation-hardening austenitic heat-resistant steel, matching UNS S66286 (A286) in composition and strengthened by γ′-Ni₃(Ti,Al) precipitates formed during ageing.
Values for the STA condition
SUH660 tempers and conditions
SUH660 is supplied in 5 conditions, soft to hard. STA is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Soft supply condition for forming, deep machining or welding before final ageing. | 285 | 655 | 45 | 190 HB | — |
Hot rolled | As-forged/hot-rolled black bar supplied for further forging or re-heat-treatment; properties not guaranteed until STA. | 420 | 800 | 30 | 20 HRC | 1.9 % IACS |
STADefault Solution treated and aged | Standard stocked condition: best balance of room-temperature strength, ductility and 650–700 °C creep/rupture life. | 725 | 1,010 | 22 | 30 HRC | — |
Low-temperature solution (~900 °C) & aged, high-strength bar | Choose for fasteners and highly stressed parts needing maximum room- and mid-temperature strength (finer grain, lower creep capability than 980 °C solution). | 790 | 1,070 | 18 | 33 HRC | — |
Cold drawn (or cold worked) and aged | Fastener wire/bar route: cold work before ageing lifts strength well above 1150 MPa at the cost of ductility and toughness. | 1,030 | 1,240 | 13 | 38 HRC | — |
What is SUH660?
SUH660 is the JIS G 4311 iron-base precipitation-hardening austenitic heat-resistant steel, matching UNS S66286 (A286) in composition and strengthened by γ′-Ni₃(Ti,Al) precipitates formed during ageing. It retains high tensile and stress-rupture strength at 650–700 °C, is non-magnetic and oxidation resistant, and is supplied as bar, wire and forgings in solution-treated and aged tempers (typically 725 MPa yield, 1010 MPa tensile, 22 % elongation, 30 HRC). Limits are poor machinability and grindability, a tendency to strain-age cracking after welding, only ~15 % Cr so pitting resistance is below 316, and a rapid strength drop above 700 °C. SUH660 has a density of 7.94 g/cm³ (0.287 lb/in³), heavier than 94% of steel grades. It melts at 1,370°C (2,498 °F). SUH660 has a yield strength of 725 MPa (105 ksi) and a tensile strength of 1,010 MPa (146 ksi) — stronger than 82% of steel grades. Elongation at break is 22% and the elastic modulus is 201 GPa (29.2 Msi).
What is SUH660 used for?
- Aircraft engine fasteners
- Gas turbine bolts and studs
- High-temperature springs
- Turbocharger wheel shafts
- Exhaust valves
- Aero-engine discs and rings
- Non-magnetic hot-section fittings
Advantages
- High service temperature — 700°C (1,292 °F), better than 99% of steel grades
- Good corrosion resistance — 58/100, better than 99% of steel grades
- Polishes to a fine finish — 75/100, better than 94% of steel grades
- Tough — resists crack growth — 130 MPa·√m (118.3 ksi·√in), better than 89% of steel grades
- High strength — 725 MPa (105 ksi), better than 82% of steel grades
Limitations
- Low electrical conductivity — 1.9 % IACS, worse than 100% of steel grades
- Poor heat conductor — 13 W/m·K (7.51 BTU/hr·ft·°F), worse than 99% of steel grades
- High embodied carbon — 6.5 kg CO₂/kg, worse than 98% of steel grades
- Difficult to machine — 20/100, worse than 97% of steel grades
SUH660 properties
Typical room-temperature values for SUH660-STA; bars are the position among steel grades.
Physical3
SUH660 has a density of 7.94 g/cm³ (0.287 lb/in³), heavier than 94% of steel grades. It melts at 1,370°C (2,498 °F).
Mechanical16
SUH660 has a yield strength of 725 MPa (105 ksi) and a tensile strength of 1,010 MPa (146 ksi) — stronger than 82% of steel grades. Elongation at break is 22% and the elastic modulus is 201 GPa (29.2 Msi).
Thermal6
SUH660 is rated for continuous service to 700°C (1,292 °F). It conducts heat at 13 W/m·K (7.51 BTU/hr·ft·°F), worse than 99% of steel grades. Thermal expansion is 16.4 µm/m·K (9.11 µin/in·°F).
Electrical3
SUH660 conducts electricity at 1.9 % IACS, worse than 100% of steel grades.
Chemical & Environmental3
Corrosion resistance is good (58/100), better than 99% of steel grades.
Sustainability4
Producing a kilogram of SUH660 takes about 90 MJ of energy and emits 6.5 kg of CO₂ — more than 98% of steel grades. Typical recycled content is 30%.
Manufacturability6
SUH660's machinability is poor (20/100, worse than 97% of steel grades); weldability good (55/100); formability poor (30/100).
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 steel family
Yield strength against density for every steel grade FabDigit runs. SUH660 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with SUH660
Is SUH660 easy to machine?
Machine like a superalloy: rigid setups, sharp positive-rake carbide or ceramic, low speed / heavy positive feed, flood coolant — it work-hardens fast and glazes if the tool dwells; rough in ST condition and finish after ageing where possible.
Can SUH660 be welded?
GTAW/EBW with matching A286 or Ni-base filler works, but keep heat input low and weld in the solution-treated state, then re-solution and age to avoid strain-age (post-weld) cracking in the HAZ.
Can SUH660 be formed, bent or molded?
Cold form only in the solution-treated condition with generous radii and high press loads; hot work at 1010–1150 °C and always finish above ~950 °C to avoid Ti-rich phase and cracking.
Manufacturability
The process limits FabDigit applies to SUH660. Every SUH660 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Fair20 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Fair30 / 100 |
|---|---|
| Weldability | Better55 / 100 |
SUH660 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 | 0.05 |
| Si | ≤ 1 | 0.5 |
| Mn | ≤ 2 | 1.2 |
| P | ≤ 0.04 | |
| S | ≤ 0.03 | |
| Ni | 24 – 27 | 25.5 |
| Cr | 13.5 – 16 | 15 |
| Mo | 1 – 1.5 | 1.25 |
| Tiγ′ Ni₃(Ti,Al) former | 1.9 – 2.35 | 2.1 |
| V | 0.1 – 0.5 | 0.3 |
| Al | ≤ 0.35 | 0.2 |
| Bgrain-boundary strengthening | 0 – 0.01 | 0.01 |
| Febalance ≈ 53 % | balance |
What surface finishes work on SUH660?
Takes a good mechanical polish and can be passivated (nitric or citric) like a stainless; not anodizable — for high-temperature threads use silver, Cu-Ni or dry-film lubricant coatings to prevent galling.
Surface treatments FabDigit runs on 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).
Plating
CVD Coating
Black / Phosphate
Thermal Spray
How much does SUH660 cost?
SUH660 is a standard-cost steel ($$), cheaper than about 71% 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.
SUH660 — frequently asked
What is SUH660 used for?
SUH660 is typically used for aircraft engine fasteners, gas turbine bolts and studs, high-temperature springs, turbocharger wheel shafts, exhaust valves and aero-engine discs and rings. In short: high-temp aerospace bar.
What is the yield strength of SUH660?
SUH660 has a typical yield strength of 725 MPa (105 ksi) and a tensile strength of 1,010 MPa (146 ksi) — stronger than 82% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is SUH660 easy to machine?
Not especially — machinability is rated poor (20/100, worse than 97% of steel grades). Machine like a superalloy: rigid setups, sharp positive-rake carbide or ceramic, low speed / heavy positive feed, flood coolant — it work-hardens fast and glazes if the tool dwells; rough in ST condition and finish after ageing where possible.
Can SUH660 be welded?
Yes — weldability is rated good (55/100). GTAW/EBW with matching A286 or Ni-base filler works, but keep heat input low and weld in the solution-treated state, then re-solution and age to avoid strain-age (post-weld) cracking in the HAZ.
What surface finishes work on SUH660?
Takes a good mechanical polish and can be passivated (nitric or citric) like a stainless; not anodizable — for high-temperature threads use silver, Cu-Ni or dry-film lubricant coatings to prevent galling.
Can SUH660 be formed, bent or molded?
Cold form only in the solution-treated condition with generous radii and high press loads; hot work at 1010–1150 °C and always finish above ~950 °C to avoid Ti-rich phase and cracking.
What is the maximum service temperature of SUH660?
SUH660 is rated for continuous use to about 700°C (1,292 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between SUH660-STA and SUH660-ST?
STA is the default condition — standard stocked condition: best balance of room-temperature strength, ductility and 650–700 °C creep/rupture life. ST: soft supply condition for forming, deep machining or welding before final ageing. Yield strength is 725 MPa in STA versus 285 MPa in ST.
How much does SUH660 cost?
SUH660 is a standard-cost steel ($$), cheaper than about 71% 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.
Can FabDigit make parts in SUH660?
Yes — SUH660 is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- JIS G 4311 — Heat-resisting steel bars — JSA (2019)
- AMS 5737 / AMS 5732 — Alloy Bars, Forgings (UNS S66286) — SAE International (2021)
- ASTM A453/A453M Grade 660 — ASTM International (2022)
- ASM Specialty Handbook: Heat-Resistant Materials — ASM International (1997)
- A286 (UNS S66286) alloy datasheet — specialty alloy producers (2023)
- GH2132/SUH660 (2025)
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.