Steel SUH660-STA (Solution treated and aged)
Heat-treated state · default condition
JIS SUH660
Standard stocked condition: best balance of room-temperature strength, ductility and 650–700 °C creep/rupture life.
Values for the STA condition
Other SUH660 tempers and conditions
SUH660 is listed in 5 conditions; see the grade overview at SUH660.
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 |
STADefaultThis page 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-STA?
SUH660-STA is SUH660 heat treated to STA — standard stocked condition: best balance of room-temperature strength, ductility and 650–700 °C creep/rupture life. SUH660-STA 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). SUH660-STA 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).
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-STA properties
Typical room-temperature values for SUH660-STA; 14 are specific to this condition. Other listed values are SUH660 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
SUH660-STA 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-STA 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-STA 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-STA 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-STA 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-STA'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. Confirm any required mill or lot documentation when quoting.
Working with SUH660-STA
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.
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.
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 |
SUH660-STA — frequently asked
What is SUH660-STA used for?
SUH660-STA 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-STA?
SUH660-STA 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-STA 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-STA 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-STA?
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-STA 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-STA?
SUH660-STA 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.
Can FabDigit make parts in SUH660-STA?
Yes — SUH660-STA 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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.