Steel SUH660 · supply condition
Steel SUH660 CD+A
Properties of the CD+A condition, compared with the other SUH660 tempers.
Fastener wire/bar route: cold work before ageing lifts strength well above 1150 MPa at the cost of ductility and toughness.
What is SUH660 CD+A?
SUH660 CD+A is SUH660 supplied in the CD+A condition — fastener wire/bar route: cold work before ageing lifts strength well above 1150 MPa at the cost of ductility and toughness. SUH660 CD+A has a yield strength of 1,030 MPa (149 ksi) and a tensile strength of 1,240 MPa (180 ksi) — stronger than 93% of steel grades. Elongation at break is 13% and the elastic modulus is 201 GPa (29.2 Msi). SUH660 CD+A has a density of 7.94 g/cm³ (0.287 lb/in³), heavier than 93% of steel grades. It melts at 1,370°C (2,498 °F). STA is the default condition FabDigit quotes; CD+A is available on request or by drawing note.
Advantages
- Good corrosion resistance — 58/100, better than 99% of steel grades
- High service temperature — 600°C (1,112 °F), better than 98% of steel grades
- Polishes to a fine finish — 75/100, better than 94% of steel grades
- High strength — 1,030 MPa (149 ksi), better than 93% of steel grades
- Tough — resists crack growth — 130 MPa·√m (118.3 ksi·√in), better than 89% 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
- Difficult to machine — 15/100, worse than 98% of steel grades
- High embodied carbon — 6.5 kg CO₂/kg, worse than 98% of steel grades
- Limited formability — 15/100, worse than 87% of steel grades
SUH660 CD+A properties
Typical room-temperature values for SUH660 CD+A — 12 properties are specific to this condition; the rest are grade-level values shared by every SUH660 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
SUH660 CD+A has a density of 7.94 g/cm³ (0.287 lb/in³), heavier than 93% of steel grades. It melts at 1,370°C (2,498 °F).
Mechanical16
SUH660 CD+A has a yield strength of 1,030 MPa (149 ksi) and a tensile strength of 1,240 MPa (180 ksi) — stronger than 93% of steel grades. Elongation at break is 13% and the elastic modulus is 201 GPa (29.2 Msi).
Thermal6
SUH660 CD+A is rated for continuous service to 600°C (1,112 °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 CD+A 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 CD+A 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 CD+A's machinability is poor (15/100, worse than 98% of steel grades); weldability fair (40/100); formability poor (15/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other SUH660 tempers and conditions
SUH660 is also supplied in 4 other conditions. The full side-by-side table is on the SUH660 overview.
- STADefaultStandard stocked condition: best balance of room-temperature strength, ductility and 650–700 °C creep/rupture life.725 MPa yield · 30 HRC
- CD+AFastener wire/bar route: cold work before ageing lifts strength well above 1150 MPa at the cost of ductility and toughness.1,030 MPa yield · 38 HRC
- STA-900Choose for fasteners and highly stressed parts needing maximum room- and mid-temperature strength (finer grain, lower creep capability than 980 °C solution).790 MPa yield · 33 HRC
- STSoft supply condition for forming, deep machining or welding before final ageing.285 MPa yield · 190 HB
Working with SUH660 CD+A
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 CD+A — frequently asked
What is SUH660 CD+A used for?
SUH660 CD+A 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 CD+A?
SUH660 CD+A has a typical yield strength of 1,030 MPa (149 ksi) and a tensile strength of 1,240 MPa (180 ksi) — stronger than 93% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is SUH660 CD+A easy to machine?
Not especially — machinability is rated poor (15/100, worse than 98% 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 CD+A be welded?
With care — weldability is rated fair (40/100). 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 CD+A?
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 CD+A 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 CD+A?
SUH660 CD+A is rated for continuous use to about 600°C (1,112 °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 CD+A?
Yes — SUH660 CD+A is available for CNC machining and sheet metal with instant online pricing. 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.