Steel SUP9 · temper · default condition
Steel SUP9 Annealed
Properties of the Annealed condition, compared with the other SUP9 tempers.
Default stock condition for machining, cold forming and subsequent heat treatment.
What is SUP9 Annealed?
SUP9 Annealed is SUP9 in the Annealed temper — default stock condition for machining, cold forming and subsequent heat treatment. SUP9 Annealed has a yield strength of 440 MPa (63.8 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 51% of steel grades. Elongation at break is 22% and the elastic modulus is 206 GPa (29.9 Msi). SUP9 Annealed has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F).
Limitations
- Limited service temperature — 250°C (482 °F), worse than 85% of steel grades
SUP9 Annealed properties
Typical room-temperature values for SUP9 Annealed — 13 properties are specific to this condition; the rest are grade-level values shared by every SUP9 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
SUP9 Annealed has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical14
SUP9 Annealed has a yield strength of 440 MPa (63.8 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 51% of steel grades. Elongation at break is 22% and the elastic modulus is 206 GPa (29.9 Msi).
Thermal6
SUP9 Annealed is rated for continuous service to 250°C (482 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), better than 71% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
SUP9 Annealed conducts electricity at 7.8 % IACS, worse than 58% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (11/100), worse than 73% of steel grades.
Sustainability4
Producing a kilogram of SUP9 Annealed takes about 26 MJ of energy and emits 2 kg of CO₂ — less than 64% of steel grades. Typical recycled content is 30%.
Manufacturability7
SUP9 Annealed's machinability is good (55/100, better than 62% of steel grades); weldability poor (30/100); 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.
Other SUP9 tempers and conditions
SUP9 is also supplied in 6 other conditions. The full side-by-side table is on the SUP9 overview.
- AnnealedDefaultDefault stock condition for machining, cold forming and subsequent heat treatment.440 MPa yield · 217 HB
- Hardened & TemperedPick for blades, agricultural tines, scrapers and wear parts where hardness matters more than toughness.1,500 MPa yield · 50 HRC
- Q&TStandard delivered condition for leaf springs, coil springs, torsion and stabiliser bars.1,250 MPa yield · 43 HRC
- Hot RolledMill as-supplied condition for spring makers who will form then quench and temper themselves.570 MPa yield · 28 HRC
- NormalizedUse to homogenise structure and refine grain before final quench and temper.530 MPa yield · 27 HRC
Working with SUP9 Annealed
Is SUP9 easy to machine?
Machine in the annealed/spheroidised state (≈60 % of 1212); above ~40 HRC use carbide or grind, and expect rapid tool wear.
Can SUP9 be welded?
Poor weldability due to high carbon equivalent — preheat 250–350 °C, low-hydrogen consumables, immediate post-weld temper, and re-heat-treat if the joint is load bearing.
Can SUP9 be formed, bent or molded?
Hot form 850–1050 °C or cold bend only when soft-annealed; harden by oil quench from 830–860 °C and temper 400–500 °C for spring temper.
What surface finishes work on SUP9?
No natural corrosion protection: shot peen for fatigue, then phosphate+oil, zinc/zinc-flake plating or epoxy paint; avoid hydrogen-embrittling plating without bake-out.
SUP9 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 |
|---|---|---|
| CSUP9A: 0.56–0.64 | 0.52 – 0.6 | 0.56 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.65 – 0.95 | 0.8 |
| CrSUP9A: 0.70–1.00 | 0.65 – 0.95 | 0.8 |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Curesidual, max | ≤ 0.3 | — |
| Niresidual, max | ≤ 0.25 | — |
| Fe | balance | — |
SUP9 Annealed — frequently asked
What is SUP9 Annealed used for?
SUP9 Annealed is typically used for coil springs, leaf springs and springs. In short: premium chromium spring bar.
What is the yield strength of SUP9 Annealed?
SUP9 Annealed has a typical yield strength of 440 MPa (63.8 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 51% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is SUP9 Annealed easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machine in the annealed/spheroidised state (≈60 % of 1212); above ~40 HRC use carbide or grind, and expect rapid tool wear.
Can SUP9 Annealed be welded?
Not readily — weldability is rated poor (30/100). Poor weldability due to high carbon equivalent — preheat 250–350 °C, low-hydrogen consumables, immediate post-weld temper, and re-heat-treat if the joint is load bearing.
What surface finishes work on SUP9 Annealed?
No natural corrosion protection: shot peen for fatigue, then phosphate+oil, zinc/zinc-flake plating or epoxy paint; avoid hydrogen-embrittling plating without bake-out.
Can SUP9 Annealed be formed, bent or molded?
Hot form 850–1050 °C or cold bend only when soft-annealed; harden by oil quench from 830–860 °C and temper 400–500 °C for spring temper.
What is the maximum service temperature of SUP9 Annealed?
SUP9 Annealed is rated for continuous use to about 250°C (482 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in SUP9 Annealed?
Yes — SUP9 Annealed 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 4801 — Spring steels — JSA (2021)
- GB/T 1222 — (55CrMnA / 60CrMnA) — SAC (2016)
- ASTM A689 / SAE J404 (5160) — ASTM / SAE (2019)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.16 — Machining; Vol.19 — Fatigue and Fracture — ASM International (1996)
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.