Steel 8650-SA (Spheroidize annealed)
Heat-treated state
AISI/SAE 8650
Subcritical spheroidizing cycle used before cold heading/upsetting of this high-carbon 8600 grade.
Values for the SA condition
Other 8650 tempers and conditions
8650 is listed in 11 conditions; see the grade overview at 8650.
Compare all 11 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SAThis page Spheroidize annealed | Subcritical spheroidizing cycle used before cold heading/upsetting of this high-carbon 8600 grade. | 360 | 660 | 26 | 12 HRC | 8.1 % IACS |
full anneal ~795 °C, slow cool | Softest condition; choose for heavy machining, cold forming or before re-hardening. | 386 | 715 | 22.5 | 212 HB | — |
HRDefault Hot rolled | Cheapest stock form for parts that will be fully heat treated after rough machining. | 550 | 860 | 18 | 24 HRC | — |
~870 °C, air cool | Uniform fine-grain structure with high as-cooled strength; use to refine forgings before final hardening. | 690 | 1,025 | 14 | 32 HRC | — |
Cold rolled | Cold-rolled strip for stamped/blanked hardenable parts where tight thickness and good surface are needed. | 700 | 900 | 10 | 26 HRC | 7.8 % IACS |
Cold drawn | Cold-drawn (usually annealed-then-drawn) bar giving straight, size-accurate stock with higher yield and better finish than hot rolled. | 790 | 930 | 12 | 28 HRC | 7.8 % IACS |
Oil quenched, high temper | Tough, readily machinable hardness band for shafts and large sections where impact matters more than wear. | 830 | 965 | 20 | 30 HRC | 7.6 % IACS |
Oil quenched, temper ~565-595 °C | Common ordering band for gears, sprockets and pins needing higher wear resistance while still machinable. | 985 | 1,110 | 16 | 36 HRC | 7.5 % IACS |
Quenched and tempered | General-purpose high-strength condition (~36-40 HRC) balancing strength, fatigue life and toughness. | 1,055 | 1,175 | 15 | 39 HRC | — |
Q&T 425 °C temper | Higher-strength/wear condition for pins, cams and light tooling where toughness demand is moderate. | 1,325 | 1,450 | 12 | 45 HRC | — |
Q&T 205 °C temper | Maximum-hardness/strength condition for wear parts; low ductility and notch sensitivity, avoid impact loading. | 1,675 | 1,930 | 10 | 54 HRC | — |
What is 8650-SA?
8650-SA is 8650 heat treated to SA — subcritical spheroidizing cycle used before cold heading/upsetting of this high-carbon 8600 grade. 8650-SA has a yield strength of 360 MPa (52.2 ksi) and a tensile strength of 660 MPa (95.7 ksi) — weaker than 72% of steel grades. Elongation at break is 26% and the elastic modulus is 205 GPa (29.7 Msi). 8650-SA 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). HR is the default condition FabDigit quotes; SA is available on request or by drawing note.
Advantages
- Ductile — tolerates forming and impact — 26%, better than 82% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
8650-SA properties
Typical room-temperature values for 8650-SA; 23 are specific to this condition. Other listed values are 8650 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
8650-SA 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).
Mechanical15
8650-SA has a yield strength of 360 MPa (52.2 ksi) and a tensile strength of 660 MPa (95.7 ksi) — weaker than 72% of steel grades. Elongation at break is 26% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
8650-SA is rated for continuous service to 400°C (752 °F). It conducts heat at 47 W/m·K (27.2 BTU/hr·ft·°F), better than 75% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
8650-SA conducts electricity at 8.1 % IACS, better than 61% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 8650-SA takes about 29 MJ of energy and emits 2.2 kg of CO₂ — less than 53% of steel grades. Typical recycled content is 30%.
Manufacturability7
8650-SA's machinability is fair (48/100, worse than 57% of steel grades); weldability poor (34/100); formability fair (52/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 8650-SA
Is 8650 easy to machine?
Best machined annealed or ≤32 HRC with rigid setups, carbide tooling and generous coolant; above ~40 HRC switch to CBN/ceramic or grinding.
Can 8650 be welded?
Poor weldability at 0.50 %C — preheat 260-370 °C, use low-hydrogen consumables and temper immediately after welding; avoid welding in the hardened condition.
Can 8650 be formed, bent or molded?
Cold forming only in the annealed/spheroidized state with generous bend radii; hot forge 1050-1200 °C then normalize before hardening.
What surface finishes work on 8650?
Not anodizable; protect with black oxide, phosphate, zinc or hard-chrome plating (bake to relieve hydrogen above 40 HRC), or take a high polish for die/tool surfaces.
8650 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 |
|---|---|---|
| C8650 = 0.50 %C nominal | 0.48 – 0.53 | 0.5 |
| Mn | 0.75 – 1 | 0.88 |
| Si | 0.15 – 0.35 | 0.25 |
| Ni | 0.4 – 0.7 | 0.55 |
| Cr | 0.4 – 0.6 | 0.5 |
| Mo | 0.15 – 0.25 | 0.2 |
| P | ≤ 0.04 | 0.02 |
| Smax; 8650H/86L50 variants differ | ≤ 0.04 | 0.03 |
| Fe | balance | — |
8650-SA — frequently asked
What is 8650-SA used for?
8650-SA is typically used for shafts, gears and axles. In short: workhorse Ni-Cr-Mo bar.
What is the yield strength of 8650-SA?
8650-SA has a typical yield strength of 360 MPa (52.2 ksi) and a tensile strength of 660 MPa (95.7 ksi) — weaker than 72% of steel grades. Strength varies by condition: see the 11 listed tempers.
Is 8650-SA easy to machine?
Reasonably — machinability is rated fair (48/100, worse than 57% of steel grades). Best machined annealed or ≤32 HRC with rigid setups, carbide tooling and generous coolant; above ~40 HRC switch to CBN/ceramic or grinding.
Can 8650-SA be welded?
Not readily — weldability is rated poor (34/100). Poor weldability at 0.50 %C — preheat 260-370 °C, use low-hydrogen consumables and temper immediately after welding; avoid welding in the hardened condition.
What surface finishes work on 8650-SA?
Not anodizable; protect with black oxide, phosphate, zinc or hard-chrome plating (bake to relieve hydrogen above 40 HRC), or take a high polish for die/tool surfaces.
Can 8650-SA be formed, bent or molded?
Cold forming only in the annealed/spheroidized state with generous bend radii; hot forge 1050-1200 °C then normalize before hardening.
What is the maximum service temperature of 8650-SA?
8650-SA is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 8650-HR and 8650-CD?
HR is the default condition — cheapest stock form for parts that will be fully heat treated after rough machining. CD: cold-drawn (usually annealed-then-drawn) bar giving straight, size-accurate stock with higher yield and better finish than hot rolled. Yield strength is 550 MPa in HR versus 790 MPa in CD.
Can FabDigit make parts in 8650-SA?
Yes — 8650-SA 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
- SAE J404 — Chemical Compositions of SAE Alloy Steels — SAE International (2021)
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought, General Requirements — ASTM (2020)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating — ASM International (1991)
- ASM Handbook Vol.16 — Machining — ASM International (1989)
- Atlas of Stress-Strain Curves / Heat Treater's Guide: Standard Steels — ASM International (1995)
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.