Copper Alloy C66900-H08
Supply condition
UNS C66900
H08 = spring hard
Spring-quality strip for contacts, clips and retaining elements requiring high elastic limit.
Values for the H08 condition
Other C66900 tempers and conditions
C66900 is listed in 8 conditions; see the grade overview at C66900.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Soft annealed | Pick when maximum drawability/bendability is needed before subsequent forming or in-service work hardening. | 205 | 480 | 45 | 55 HRB | — |
Quarter hard | Lightest rolled temper — use when moderate strength must be combined with substantial bending and forming. | 380 | 585 | 22 | 75 HRB | — |
Half hard | General-purpose stamping temper balancing strength with 90° bend capability across the grain. | 450 | 625 | 15 | 82 HRB | — |
Three-quarter hard | Intermediate step when H02 lacks yield strength but H04 is too stiff to form. | 510 | 660 | 11 | 85 HRB | — |
H04Default Full hard | Most commonly stocked condition — high strength and wear resistance for flat structural parts and gentle bends. | 565 | 700 | 7 | 88 HRB | — |
Extra hard | Use for flat springs, wear washers and shims where high yield strength matters more than bend ductility. | 640 | 760 | 5 | 92 HRB | — |
H08This page Spring hard | Spring-quality strip for contacts, clips and retaining elements requiring high elastic limit. | 690 | 800 | 4 | 95 HRB | — |
Extra spring hard | Highest-strength rolled condition; specify only for flat or large-radius parts with minimal forming. | 725 | 830 | 3 | 97 HRB | — |
What is C66900-H08?
C66900-H08 is C66900 supplied in the H08 condition — spring-quality strip for contacts, clips and retaining elements requiring high elastic limit. C66900-H08 has a yield strength of 690 MPa (100 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 96% of copper alloy grades. Elongation at break is 4% and the elastic modulus is 105 GPa (15.2 Msi). C66900-H08 has a density of 8.1 g/cm³ (0.293 lb/in³), lighter than 86% of copper alloy grades. It melts at 880°C (1,616 °F). H04 is the default condition FabDigit quotes; H08 is available on request or by drawing note.
Advantages
- High strength — 690 MPa (100 ksi), better than 96% of copper alloy grades
Limitations
- Limited service temperature — 140°C (284 °F), worse than 100% of copper alloy grades
- Low electrical conductivity — 4.5 % IACS, worse than 98% of copper alloy grades
- Poor heat conductor — 27 W/m·K (15.6 BTU/hr·ft·°F), worse than 97% of copper alloy grades
- Limited ductility — 4%, worse than 96% of copper alloy grades
- Limited formability — 12/100, worse than 85% of copper alloy grades
C66900-H08 properties
Typical room-temperature values for C66900-H08; 10 are specific to this condition. Other listed values are C66900 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C66900-H08 has a density of 8.1 g/cm³ (0.293 lb/in³), lighter than 86% of copper alloy grades. It melts at 880°C (1,616 °F).
Mechanical12
C66900-H08 has a yield strength of 690 MPa (100 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 96% of copper alloy grades. Elongation at break is 4% and the elastic modulus is 105 GPa (15.2 Msi).
Thermal6
C66900-H08 is rated for continuous service to 140°C (284 °F). It conducts heat at 27 W/m·K (15.6 BTU/hr·ft·°F), worse than 97% of copper alloy grades. Thermal expansion is 20 µm/m·K (11.1 µin/in·°F).
Electrical3
C66900-H08 conducts electricity at 4.5 % IACS, worse than 98% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 57% of copper alloy grades.
Sustainability4
Producing a kilogram of C66900-H08 takes about 55 MJ of energy and emits 3.5 kg of CO₂ — less than 72% of copper alloy grades. Typical recycled content is 40%.
Manufacturability8
C66900-H08's machinability is poor (30/100, worse than 67% of copper alloy grades); weldability fair (40/100); formability not recommended (12/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C66900-H08
Is C66900 easy to machine?
Unleaded and work-hardened: use sharp carbide, positive rake, 0.05–0.15 mm/rev feeds and flood coolant; expect gummy chips and ~30 % of free-cutting brass throughput.
Can C66900 be welded?
Best joined by resistance spot/seam welding or silver brazing; fusion welding causes zinc fuming, porosity and loss of temper — use local extraction and avoid heating cold-worked strip above ~250 °C.
Can C66900 be formed, bent or molded?
Form in O60/H01–H02; in H04 and harder restrict to gentle bends with generous radii and bend across the rolling direction, and stress-relieve 200–260 °C to prevent season cracking.
What surface finishes work on C66900?
Not anodizable — bright dip and clear lacquer, or nickel/chrome/tin plating after thorough oxide removal (Mn-rich film needs activated cleaning); polishes to a bright warm finish.
C66900 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 |
|---|---|---|
| Cuper CDA/UNS registration for C66900; confirm against mill certificate | 63 – 68 | 65.5 |
| Mnprincipal strengthening addition — distinguishes C66900 from C66700/C66800 | 11 – 13 | 12 |
| Fe | ≤ 0.5 | — |
| Al | ≤ 0.5 | — |
| Pb | ≤ 0.05 | — |
| Znremainder, nominally ~22–24 % | balance | — |
C66900-H08 — frequently asked
What is C66900-H08 used for?
C66900-H08 is typically used for gears and wear parts, structural fasteners and marine hardware. In short: highest-strength manganese brass; 700 MPa tensile strip; wear-resistant structural grade.
What is the yield strength of C66900-H08?
C66900-H08 has a typical yield strength of 690 MPa (100 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 96% of copper alloy grades. Strength varies by condition: see the 8 listed tempers.
Is C66900-H08 easy to machine?
Not especially — machinability is rated poor (30/100, worse than 67% of copper alloy grades). Unleaded and work-hardened: use sharp carbide, positive rake, 0.05–0.15 mm/rev feeds and flood coolant; expect gummy chips and ~30 % of free-cutting brass throughput.
Can C66900-H08 be welded?
With care — weldability is rated fair (40/100). Best joined by resistance spot/seam welding or silver brazing; fusion welding causes zinc fuming, porosity and loss of temper — use local extraction and avoid heating cold-worked strip above ~250 °C.
What surface finishes work on C66900-H08?
Not anodizable — bright dip and clear lacquer, or nickel/chrome/tin plating after thorough oxide removal (Mn-rich film needs activated cleaning); polishes to a bright warm finish.
Can C66900-H08 be formed, bent or molded?
Form in O60/H01–H02; in H04 and harder restrict to gentle bends with generous radii and bend across the rolling direction, and stress-relieve 200–260 °C to prevent season cracking.
What is the maximum service temperature of C66900-H08?
C66900-H08 is rated for continuous use to about 140°C (284 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C66900-H04 and C66900-O60?
H04 is the default condition — most commonly stocked condition — high strength and wear resistance for flat structural parts and gentle bends. O60: pick when maximum drawability/bendability is needed before subsequent forming or in-service work hardening. Yield strength is 565 MPa in H04 versus 205 MPa in O60.
Sources
- CDA/UNS Copper Alloy Registration & Alloy Data — C669xx manganese brasses — Copper Development Association (2023)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
- ASM Handbook Vol. 13B — Corrosion: Materials (brasses, dezincification, SCC) — ASM International (2005)
- ASTM B36/B36M — Brass Plate, Sheet, Strip and Rolled Bar (temper designations per ASTM B601) — ASTM International (2018)
- ASTM B601 — Temper Designations for Copper and Copper Alloys — ASTM International (2019)
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.