Steel 8650
AISI/SAE 8650
8650 is a medium-carbon Ni-Cr-Mo through-hardening alloy steel at about 0.50 % C, the highest-carbon grade in common use from the 8600 series, with greater hardenability and higher tempered strength than 8640.
Values for the HR condition
8650 tempers and conditions
8650 is supplied in 11 conditions, soft to hard. HR is the default FabDigit quotes; the values on this page are for it.
Compare all 11 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
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?
8650 is a medium-carbon Ni-Cr-Mo through-hardening alloy steel at about 0.50 % C, the highest-carbon grade in common use from the 8600 series, with greater hardenability and higher tempered strength than 8640. It is stocked as hot-rolled, cold-drawn, annealed, normalized and quenched-and-tempered bar for shafts, gears, pins, fasteners and tool fixtures that need strength and wear resistance with moderate toughness; oil quenching gives a stable 40–55 HRC. Weldability is poor at this carbon level, cold forming and machining are harder than on 8640, and corrosion resistance matches plain carbon steel, so a coating or plating is required. 8650 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). 8650 has a yield strength of 550 MPa (79.8 ksi) and a tensile strength of 860 MPa (125 ksi) — stronger than 71% of steel grades. Elongation at break is 18% and the elastic modulus is 205 GPa (29.7 Msi).
What is 8650 used for?
- Shafts
- Gears
- Axles
Advantages
- Polishes to a fine finish — 65/100, better than 78% of steel grades
8650 properties
Typical room-temperature values for 8650-HR; bars are the position among steel grades.
Physical3
8650 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 has a yield strength of 550 MPa (79.8 ksi) and a tensile strength of 860 MPa (125 ksi) — stronger than 71% of steel grades. Elongation at break is 18% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
8650 is rated for continuous service to 400°C (752 °F). It conducts heat at 45 W/m·K (26 BTU/hr·ft·°F), better than 66% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
8650 conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 8650 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's machinability is fair (42/100, worse than 73% of steel grades); weldability poor (28/100); 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. 8650 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 8650
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.
Manufacturability
The process limits FabDigit applies to 8650. Every 8650 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Better42 / 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 | Better28 / 100 |
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 |
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.
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 8650 cost?
8650 is a standard-cost steel ($$), cheaper than about 61% 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.
8650 — frequently asked
What is 8650 used for?
8650 is typically used for shafts, gears and axles. In short: workhorse Ni-Cr-Mo bar.
What is the yield strength of 8650?
8650 has a typical yield strength of 550 MPa (79.8 ksi) and a tensile strength of 860 MPa (125 ksi) — stronger than 71% of steel grades. Strength varies by condition: see the 11 listed tempers.
Is 8650 easy to machine?
Not especially — machinability is rated fair (42/100, worse than 73% 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 be welded?
Not readily — weldability is rated poor (28/100). 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?
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 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?
8650 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.
How much does 8650 cost?
8650 is a standard-cost steel ($$), cheaper than about 61% 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 8650?
Yes — 8650 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; 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.