Steel 8660-CR (Cold rolled)
Supply condition
AISI/SAE 8660 · UNS G86600
Strip/sheet form for blanking and spring-type parts that are subsequently hardened and tempered.
Values for the CR condition
Other 8660 tempers and conditions
8660 is listed in 10 conditions; see the grade overview at 8660.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
full/spheroidize anneal, softest machining condition | Pick when maximum machinability or cold-forming ability is needed before hardening. | 460 | 800 | 20 | 230 HB | — |
HRDefault Hot rolled | Standard stock condition for bar and plate that will be machined and then heat treated by the user. | 585 | 965 | 13 | 29 HRC | 7.2 % IACS |
austenitized ~870 °C, air cooled | Use to homogenize forgings and refine grain before hardening; gives high strength but low ductility for this carbon level. | 690 | 1,105 | 14 | 34 HRC | 7 % IACS |
Cold drawn | Choose for close size tolerance and straight bright bar where no further heat treatment is planned. | 790 | 930 | 10 | 28 HRC | 7.2 % IACS |
CRThis page Cold rolled | Strip/sheet form for blanking and spring-type parts that are subsequently hardened and tempered. | 800 | 950 | 9 | 29 HRC | 7.2 % IACS |
Quenched and high-temperature tempered | Tough, machinable strength level for larger shafts and torsion members where impact matters. | 855 | 965 | 17 | 30 HRC | — |
Quenched and tempered ~540 °C | Balanced strength/toughness level widely specified for gears and highly loaded shafting. | 1,000 | 1,110 | 15 | 35 HRC | — |
Quenched and tempered | General-purpose hardened-and-tempered condition for shafts and machine parts needing high strength with usable toughness. | 1,080 | 1,200 | 13 | 38 HRC | — |
Quenched and tempered ~430 °C | High-strength wear-resistant level for cams, sprockets and tool bodies; ductility drops noticeably. | 1,280 | 1,400 | 11 | 42 HRC | — |
Quenched and low-temperature tempered | Maximum practical hardness/wear level for this grade; use only where impact and notch sensitivity are controlled. | 1,500 | 1,720 | 8 | 50 HRC | — |
What is 8660-CR?
8660-CR is 8660 supplied in the CR condition — strip/sheet form for blanking and spring-type parts that are subsequently hardened and tempered. 8660-CR has a yield strength of 800 MPa (116 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 86% of steel grades. Elongation at break is 9% and the elastic modulus is 205 GPa (29.7 Msi). 8660-CR has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,415°C (2,579 °F). HR is the default condition FabDigit quotes; CR is available on request or by drawing note.
Advantages
- High strength — 800 MPa (116 ksi), better than 86% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Limited ductility — 9%, worse than 93% of steel grades
- Difficult to weld — 18/100, worse than 87% of steel grades
- Low fracture toughness — 50 MPa·√m (45.5 ksi·√in), worse than 86% of steel grades
- Limited formability — 20/100, worse than 80% of steel grades
8660-CR properties
Typical room-temperature values for 8660-CR; 22 are specific to this condition. Other listed values are 8660 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
8660-CR has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,415°C (2,579 °F).
Mechanical16
8660-CR has a yield strength of 800 MPa (116 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 86% of steel grades. Elongation at break is 9% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
8660-CR is rated for continuous service to 400°C (752 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 11.7 µm/m·K (6.5 µin/in·°F).
Electrical3
8660-CR conducts electricity at 7.2 % IACS, worse than 71% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (11/100), worse than 73% of steel grades.
Sustainability4
Producing a kilogram of 8660-CR takes about 30 MJ of energy and emits 2.2 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 30%.
Manufacturability6
8660-CR's machinability is fair (42/100, worse than 73% of steel grades); weldability poor (18/100); formability poor (20/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 8660-CR
Is 8660 easy to machine?
Machine in the annealed or ≤32 HRC condition with rigid setups, carbide tooling and generous coolant; above ~40 HRC switch to grinding or CBN turning.
Can 8660 be welded?
Poor weldability at 0.60 % C — avoid if possible; if required use low-hydrogen consumables, 250–350 °C preheat, interpass control and immediate post-weld temper.
Can 8660 be formed, bent or molded?
Cold forming is limited to mild bends in the spheroidize-annealed state; hot forge at 1100–1200 °C, finish above 900 °C and slow cool or normalize afterwards.
What surface finishes work on 8660?
Not anodizable; protect with phosphate + oil, black oxide, zinc or hard chrome, and stress-relieve/bake after plating to avoid hydrogen embrittlement at high hardness.
8660 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 | 0.56 – 0.64 | 0.6 |
| 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 | — |
| S | ≤ 0.04 | — |
| Fe | balance | — |
8660-CR — frequently asked
What is 8660-CR used for?
8660-CR is typically used for drive shafts, pinion shafts, gears and gear blanks, torsion bars and spring anchors, wear plates and liners and forged sprockets and couplings. In short: workhorse Ni-Cr-Mo bar.
What is the yield strength of 8660-CR?
8660-CR has a typical yield strength of 800 MPa (116 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 86% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is 8660-CR easy to machine?
Not especially — machinability is rated fair (42/100, worse than 73% of steel grades). Machine in the annealed or ≤32 HRC condition with rigid setups, carbide tooling and generous coolant; above ~40 HRC switch to grinding or CBN turning.
Can 8660-CR be welded?
Not readily — weldability is rated poor (18/100). Poor weldability at 0.60 % C — avoid if possible; if required use low-hydrogen consumables, 250–350 °C preheat, interpass control and immediate post-weld temper.
What surface finishes work on 8660-CR?
Not anodizable; protect with phosphate + oil, black oxide, zinc or hard chrome, and stress-relieve/bake after plating to avoid hydrogen embrittlement at high hardness.
Can 8660-CR be formed, bent or molded?
Cold forming is limited to mild bends in the spheroidize-annealed state; hot forge at 1100–1200 °C, finish above 900 °C and slow cool or normalize afterwards.
What is the maximum service temperature of 8660-CR?
8660-CR 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 8660-HR and 8660-CR?
HR is the default condition — standard stock condition for bar and plate that will be machined and then heat treated by the user. CR: strip/sheet form for blanking and spring-type parts that are subsequently hardened and tempered. Yield strength is 585 MPa in HR versus 800 MPa in CR.
Can FabDigit make parts in 8660-CR?
Yes — 8660-CR 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 — ASTM (2020)
- SAE J1268 — Hardenability Bands for Carbon and Alloy H Steels — SAE International (2019)
- 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)
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.