Steel 8642-CD (Cold drawn)
Supply condition
AISI/SAE 8642 · UNS G86420
Tight tolerance, bright bar with raised yield strength for shafts machined without further heat treatment.
Values for the CD condition
Other 8642 tempers and conditions
8642 is listed in 13 conditions; see the grade overview at 8642.
Compare all 13 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Choose for cold heading, thread rolling or severe cold forming of this medium-carbon alloy. | 400 | 655 | 25 | 179 HB | 8 % IACS |
Solution annealed | Softest condition for deep machining, cold work or before final heat treatment. | 435 | 710 | 21 | 192 HB | — |
Hot rolled | Lowest-cost mill condition for parts that will be fully heat treated after rough machining. | 490 | 830 | 18 | 23 HRC | 8 % IACS |
CDThis page Cold drawn | Tight tolerance, bright bar with raised yield strength for shafts machined without further heat treatment. | 690 | 800 | 12 | 21 HRC | 8 % IACS |
Normalized | Uniform fine-grain structure and moderate strength before Q&T, or for parts not needing full hardening. | 700 | 1,050 | 20 | 33 HRC | 7.9 % IACS |
Q&T | Toughest Q&T setting; pick for shock-loaded or weld-repaired parts and for easier machining. | 830 | 930 | 19 | 28 HRC | — |
Q&T to 28–32 HRC | Common purchase spec for heavy shafts where machinability and toughness matter more than peak strength. | 860 | 970 | 18 | 30 HRC | 7.9 % IACS |
QT540Default Q&T | The standard stocked condition: best strength/toughness balance for general machined power-transmission parts. | 1,020 | 1,130 | 15 | 34 HRC | — |
Induction hardened | Select when a wear-resistant 55+ HRC surface with compressive residual stress is needed on a tough Q&T core. | 1,020 | 1,130 | 13 | 56 HRC | 7.4 % IACS |
Q&T to 38–42 HRC | High-strength hardness band for gears, pins and hydraulic components; machine before final temper if possible. | 1,200 | 1,340 | 13 | 40 HRC | 7.6 % IACS |
Q&T | High-strength setting (~40–44 HRC) for heavily loaded shafts, gears and fasteners. | 1,290 | 1,430 | 12 | 43 HRC | — |
Q&T | Very high strength; falls in the temper-embrittlement range, so use only where toughness is not critical. | 1,570 | 1,720 | 10 | 49 HRC | — |
Q&T | Maximum hardness and strength for wear parts; very low ductility and notch sensitivity — avoid impact loading. | 1,720 | 1,930 | 9 | 54 HRC | — |
What is 8642-CD?
8642-CD is 8642 supplied in the CD condition — tight tolerance, bright bar with raised yield strength for shafts machined without further heat treatment. 8642-CD has a yield strength of 690 MPa (100 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 80% of steel grades. Elongation at break is 12% and the elastic modulus is 205 GPa (29.7 Msi). 8642-CD 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). QT540 is the default condition FabDigit quotes; CD is available on request or by drawing note.
Advantages
- Easy to machine — 62/100, better than 89% of steel grades
- High strength — 690 MPa (100 ksi), better than 80% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Limited ductility — 12%, worse than 84% of steel grades
- Low fracture toughness — 65 MPa·√m (59.2 ksi·√in), worse than 75% of steel grades
8642-CD properties
Typical room-temperature values for 8642-CD; 23 are specific to this condition. Other listed values are 8642 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
8642-CD 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).
Mechanical16
8642-CD has a yield strength of 690 MPa (100 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 80% of steel grades. Elongation at break is 12% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
8642-CD is rated for continuous service to 400°C (752 °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
8642-CD conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 8642-CD takes about 34 MJ of energy and emits 2.4 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
8642-CD's machinability is good (62/100, better than 89% of steel grades); weldability fair (35/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 8642-CD
Is 8642 easy to machine?
Best machined at 200–300 HB (annealed/normalized or Q&T ≤32 HRC); use rigid setups, carbide inserts and generous coolant, then finish-temper to final hardness.
Can 8642 be welded?
Weldable with low-hydrogen consumables but CE ≈ 0.8 demands 200–320 °C preheat, controlled interpass and immediate post-weld temper/stress relief to avoid cold cracking.
Can 8642 be formed, bent or molded?
Cold form only in annealed or spheroidized condition; hot forge 1100–1200 °C and finish above ~870 °C, then slow cool or normalize before hardening.
What surface finishes work on 8642?
No anodizing — protect with phosphate + oil, black oxide, zinc or Cr plating; bake plated high-strength parts at 190–220 °C to relieve hydrogen embrittlement; polishes well after Q&T.
8642 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 |
|---|---|---|
| CSAE J404 heat analysis | 0.4 – 0.45 | 0.42 |
| 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 | — |
| Smax; H-grade/resulfurized variants differ | ≤ 0.04 | — |
| Fe | balance | — |
8642-CD — frequently asked
What is 8642-CD used for?
8642-CD is typically used for automotive axle shafts, gears, high-strength studs and bolts and machinery shafts. In short: stronger than 8640 Q&T; good medium-section hardenability; demanding weldability.
What is the yield strength of 8642-CD?
8642-CD has a typical yield strength of 690 MPa (100 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 80% of steel grades. Strength varies by condition: see the 13 listed tempers.
Is 8642-CD easy to machine?
Reasonably — machinability is rated good (62/100, better than 89% of steel grades). Best machined at 200–300 HB (annealed/normalized or Q&T ≤32 HRC); use rigid setups, carbide inserts and generous coolant, then finish-temper to final hardness.
Can 8642-CD be welded?
With care — weldability is rated fair (35/100). Weldable with low-hydrogen consumables but CE ≈ 0.8 demands 200–320 °C preheat, controlled interpass and immediate post-weld temper/stress relief to avoid cold cracking.
What surface finishes work on 8642-CD?
No anodizing — protect with phosphate + oil, black oxide, zinc or Cr plating; bake plated high-strength parts at 190–220 °C to relieve hydrogen embrittlement; polishes well after Q&T.
Can 8642-CD be formed, bent or molded?
Cold form only in annealed or spheroidized condition; hot forge 1100–1200 °C and finish above ~870 °C, then slow cool or normalize before hardening.
What is the maximum service temperature of 8642-CD?
8642-CD 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 8642-QT540 and 8642-QT205?
QT540 is the default condition — the standard stocked condition: best strength/toughness balance for general machined power-transmission parts. QT205: maximum hardness and strength for wear parts; very low ductility and notch sensitivity — avoid impact loading. Yield strength is 1,020 MPa in QT540 versus 1,720 MPa in QT205.
Sources
- SAE J404 — Chemical Compositions of SAE Alloy Steels — SAE International (2021)
- SAE J1268 — Hardenability Bands for Alloy H-Steels — SAE International (2019)
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought — 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)
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.