Copper Alloy C66300-HR10
Heat-treated state
UNS C66300 · ASTM B592
HR10 = extra spring temper and stress relieved
Extra-spring strip stabilised by stress relief for maximum elastic limit with controlled flatness and reduced SCC sensitivity.
Values for the HR10 condition
Other C66300 tempers and conditions
C66300 is listed in 11 conditions; see the grade overview at C66300.
Compare all 11 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Soft annealed | Pick for deep drawing, severe forming or re-rolling before final temper rolling. | 145 | 375 | 45 | 85 HB | 27 % IACS |
Annealed to temper, half-hard level | Use where half-hard strength is needed together with a fully recrystallised, forming-friendly structure and low residual stress. | 275 | 450 | 25 | 60 HRB | — |
Half hard | General-purpose stamping temper when moderate strength plus some bend ductility is required. | 400 | 500 | 15 | 68 HRB | — |
Full hard | Standard stocked hard strip for fasteners, clips and lightly loaded flat springs. | 490 | 570 | 8 | 78 HRB | — |
Full hard and stress relieved | Choose when full-hard strength must be combined with low residual stress (flatness, reduced SCC risk in ammonia-bearing service). | 540 | 585 | 8 | 79 HRB | — |
Extra hard | Step up from full hard for higher elastic limit where only gentle forming (bends along grain) is needed. | 550 | 620 | 5 | 82 HRB | — |
H08Default Spring hard | Default stocked spring-strip temper: best balance of elastic limit and formability for stamped springs and contacts. | 600 | 660 | 3.5 | 85 HRB | — |
Spring temper and stress relieved | Spring temper with a low-temperature stress relief for higher elastic limit, better flatness and less relaxation in service. | 630 | 670 | 3.5 | 86 HRB | — |
Extra spring hard | For higher spring rate and load capacity in flat springs where bend radii can be kept large. | 640 | 700 | 3 | 88 HRB | — |
HR10This page Extra spring temper and stress relieved | Extra-spring strip stabilised by stress relief for maximum elastic limit with controlled flatness and reduced SCC sensitivity. | 670 | 710 | 3 | 89 HRB | — |
Strain hardened, half hard | Maximum cold-rolled strength for very high spring loads in flat parts with minimal forming. | 690 | 740 | 2 | 90 HRB | — |
What is C66300-HR10?
C66300-HR10 is C66300 heat treated to HR10 — extra-spring strip stabilised by stress relief for maximum elastic limit with controlled flatness and reduced SCC sensitivity. C66300-HR10 has a yield strength of 670 MPa (97.2 ksi) and a tensile strength of 710 MPa (103 ksi) — stronger than 96% of copper alloy grades. Elongation at break is 3% and the elastic modulus is 110 GPa (16 Msi). C66300-HR10 has a density of 8.55 g/cm³ (0.309 lb/in³), lighter than 60% of copper alloy grades. It melts at 900°C (1,652 °F). H08 is the default condition FabDigit quotes; HR10 is available on request or by drawing note.
Advantages
- High strength — 670 MPa (97.2 ksi), better than 96% of copper alloy grades
Limitations
- Limited ductility — 3%, worse than 97% of copper alloy grades
- Limited service temperature — 150°C (302 °F), worse than 96% of copper alloy grades
- Limited formability — 14/100, worse than 84% of copper alloy grades
C66300-HR10 properties
Typical room-temperature values for C66300-HR10; 10 are specific to this condition. Other listed values are C66300 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C66300-HR10 has a density of 8.55 g/cm³ (0.309 lb/in³), lighter than 60% of copper alloy grades. It melts at 900°C (1,652 °F).
Mechanical11
C66300-HR10 has a yield strength of 670 MPa (97.2 ksi) and a tensile strength of 710 MPa (103 ksi) — stronger than 96% of copper alloy grades. Elongation at break is 3% and the elastic modulus is 110 GPa (16 Msi).
Thermal6
C66300-HR10 is rated for continuous service to 150°C (302 °F). It conducts heat at 105 W/m·K (60.7 BTU/hr·ft·°F), better than 56% of copper alloy grades. Thermal expansion is 19.9 µm/m·K (11.1 µin/in·°F).
Electrical3
C66300-HR10 conducts electricity at 25 % IACS, better than 59% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 57% of copper alloy grades.
Sustainability4
Producing a kilogram of C66300-HR10 takes about 58 MJ of energy and emits 3.6 kg of CO₂ — more than 61% of copper alloy grades. Typical recycled content is 50%.
Manufacturability7
C66300-HR10's machinability is fair (35/100, better than 51% of copper alloy grades); weldability poor (30/100); formability not recommended (14/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C66300-HR10
Is C66300 easy to machine?
Unleaded tin brass machines to roughly 30 % of free-cutting brass — use sharp positive-rake tools, high speed, light feed and emulsion coolant to avoid gummy chips.
Can C66300 be welded?
Not suited to fusion arc welding (zinc fume/porosity); join by resistance spot/seam welding, soft soldering or silver brazing with ventilation.
Can C66300 be formed, bent or molded?
Blank and form from O82/H02 for deep shapes; in spring tempers bend with the bend axis across the rolling direction and generous radii, then stress-relieve stamped springs at ~200–250 °C to set shape and cut relaxation.
What surface finishes work on C66300?
Takes bright mechanical polishing; commonly tin-, nickel-, silver- or gold-plated for contacts, or lacquered/passivated to prevent tarnish. No anodising.
C66300 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 |
|---|---|---|
| Curegistered range per CDA/ASTM listing for this Cu-Zn-Sn alloy — verify against the current standard before ordering | 68.5 – 71.5 | 70 |
| Sntin addition for strength and dezincification resistance | 2 – 3 | 2.5 |
| Feimpurity limit | ≤ 0.05 | — |
| Pbimpurity limit | ≤ 0.05 | — |
| Znremainder, nominally ~27 % | balance | — |
C66300-HR10 — frequently asked
What is C66300-HR10 used for?
C66300-HR10 is typically used for springs, fasteners, electrical contacts and precision stampings. In short: spring-temper tin brass; 600 MPa yield strip; low formability, high strength.
What is the yield strength of C66300-HR10?
C66300-HR10 has a typical yield strength of 670 MPa (97.2 ksi) and a tensile strength of 710 MPa (103 ksi) — stronger than 96% of copper alloy grades. Strength varies by condition: see the 11 listed tempers.
Is C66300-HR10 easy to machine?
Not especially — machinability is rated fair (35/100, better than 51% of copper alloy grades). Unleaded tin brass machines to roughly 30 % of free-cutting brass — use sharp positive-rake tools, high speed, light feed and emulsion coolant to avoid gummy chips.
Can C66300-HR10 be welded?
Not readily — weldability is rated poor (30/100). Not suited to fusion arc welding (zinc fume/porosity); join by resistance spot/seam welding, soft soldering or silver brazing with ventilation.
What surface finishes work on C66300-HR10?
Takes bright mechanical polishing; commonly tin-, nickel-, silver- or gold-plated for contacts, or lacquered/passivated to prevent tarnish. No anodising.
Can C66300-HR10 be formed, bent or molded?
Blank and form from O82/H02 for deep shapes; in spring tempers bend with the bend axis across the rolling direction and generous radii, then stress-relieve stamped springs at ~200–250 °C to set shape and cut relaxation.
What is the maximum service temperature of C66300-HR10?
C66300-HR10 is rated for continuous use to about 150°C (302 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C66300-H08 and C66300-O60?
H08 is the default condition — default stocked spring-strip temper: best balance of elastic limit and formability for stamped springs and contacts. O60: pick for deep drawing, severe forming or re-rolling before final temper rolling. Yield strength is 600 MPa in H08 versus 145 MPa in O60.
Sources
- ASTM B592 — Copper-alloy plate, sheet, strip and rolled bar (Cu-Zn based high-strength alloys) — ASTM International (2021)
- ASTM B601 — Temper Designations for Copper and Copper Alloys — ASTM International (2019)
- CDA/copper.org Standard Designations & Alloy Property Database — Copper Development Association (2023)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
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.