Copper Alloy C64800-TH04
Precip hard
UNS C64800
TH04 = tD04 and precipitation hardened
High-strength mill-hardened condition for contact springs and clips.
Values for the TH04 condition
Other C64800 tempers and conditions
C64800 is listed in 9 conditions; see the grade overview at C64800.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Soft annealed | Softest condition for maximum drawability or deep forming before hardening. | 140 | 380 | 40 | 80 HB | 30 % IACS |
Solution heat treated | Supersaturated, ductile starting condition for forming or wire drawing before aging. | 165 | 410 | 35 | 88 HB | 22 % IACS |
Solution heat treated and cold worked, half hard | Intermediate strength/ductility balance for parts that will still be bent or formed. | 420 | 500 | 12 | 135 HB | 21 % IACS |
Solution heat treated and cold worked, full hard | Work-hardened wire/strip when no subsequent aging step is available. | 500 | 570 | 8 | 168 HB | 20 % IACS |
TF00Default Solution heat treated and precipitation hardened | Standard stocked condition: best combination of strength, conductivity and stability after aging. | 590 | 690 | 10 | 93 HRB | 45 % IACS |
Cold worked spring temper | Heavily drawn fine wire for springs where a bake/age cycle is not applied. | 600 | 660 | 3 | 12 HRC | 19 % IACS |
TD02 and precipitation hardened | Mill-hardened half-hard strip/wire when moderate formability must survive with high strength. | 650 | 720 | 8 | 17 HRC | 44 % IACS |
TH04This page TD04 and precipitation hardened | High-strength mill-hardened condition for contact springs and clips. | 720 | 790 | 5 | 21 HRC | 43 % IACS |
Spring temper cold worked then precipitation hardened | Maximum-strength fine wire/strip for highly stressed springs and connectors. | 810 | 860 | 2 | 26 HRC | 42 % IACS |
What is C64800-TH04?
C64800-TH04 is C64800 in the TH04 condition — high-strength mill-hardened condition for contact springs and clips. C64800-TH04 has a yield strength of 720 MPa (104 ksi) and a tensile strength of 790 MPa (115 ksi) — stronger than 97% of copper alloy grades. Elongation at break is 5% and the elastic modulus is 132 GPa (19.1 Msi). C64800-TH04 has a density of 8.8 g/cm³ (0.318 lb/in³), heavier than 58% of copper alloy grades. It melts at 1,030°C (1,886 °F). TF00 is the default condition FabDigit quotes; TH04 is available on request or by drawing note.
Advantages
- High strength — 720 MPa (104 ksi), better than 97% of copper alloy grades
- Stiff — 132 GPa (19.1 Msi), better than 93% of copper alloy grades
- High electrical conductivity — 43 % IACS, better than 75% of copper alloy grades
Limitations
- Limited ductility — 5%, worse than 93% of copper alloy grades
C64800-TH04 properties
Typical room-temperature values for C64800-TH04; 21 are specific to this condition. Other listed values are C64800 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C64800-TH04 has a density of 8.8 g/cm³ (0.318 lb/in³), heavier than 58% of copper alloy grades. It melts at 1,030°C (1,886 °F).
Mechanical11
C64800-TH04 has a yield strength of 720 MPa (104 ksi) and a tensile strength of 790 MPa (115 ksi) — stronger than 97% of copper alloy grades. Elongation at break is 5% and the elastic modulus is 132 GPa (19.1 Msi).
Thermal6
C64800-TH04 is rated for continuous service to 200°C (392 °F). It conducts heat at 170 W/m·K (98.2 BTU/hr·ft·°F), better than 74% of copper alloy grades. Thermal expansion is 17.5 µm/m·K (9.72 µin/in·°F).
Electrical3
C64800-TH04 conducts electricity at 43 % IACS, better than 75% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is very good (70/100), better than 76% of copper alloy grades.
Sustainability4
Producing a kilogram of C64800-TH04 takes about 58 MJ of energy and emits 3.8 kg of CO₂ — more than 61% of copper alloy grades. Typical recycled content is 30%.
Manufacturability7
C64800-TH04's machinability is fair (38/100, better than 55% of copper alloy grades); weldability fair (50/100); formability poor (30/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C64800-TH04
Is C64800 easy to machine?
Machines like other silicon bronzes — gummy, ~30 % of AISI 1212; use sharp positive-rake tools, high speed, generous coolant, and machine in the aged condition for better chip control.
Can C64800 be welded?
GTAW/resistance and laser welding are feasible with silicon-bronze filler, but the aged strength is lost in the HAZ, so re-age or design joints away from spring sections; remove silica film before welding.
Can C64800 be formed, bent or molded?
Do heavy drawing, coiling and bending in the solution-treated or partly cold-worked state, then age at ~450–500 °C for strength recovery and springback stabilization.
What surface finishes work on C64800?
No anodizing; tin, nickel or gold plating for contacts (nickel underplate recommended), and it polishes well or can be chemically patinated for decorative use.
C64800 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 |
|---|---|---|
| Siprimary precipitate former with Co (Co–Si intermetallics); nominal, verify against CDA/UNS registration | 1.4 – 2.2 | 1.8 |
| Cocobalt addition gives the precipitation-hardening response | 0.3 – 1.2 | 0.7 |
| Feimpurity/partial Co substitute | ≤ 0.3 | — |
| Znimpurity limit | ≤ 0.5 | — |
| Pbimpurity limit | ≤ 0.05 | — |
| Curemainder, ~96–98 % | balance | — |
C64800-TH04 — frequently asked
What is C64800-TH04 used for?
C64800-TH04 is typically used for springs, electrical contacts and fine wire. In short: highest-strength silicon bronze; spring alloy with 45% IACS; age-hardenable contact material.
What is the yield strength of C64800-TH04?
C64800-TH04 has a typical yield strength of 720 MPa (104 ksi) and a tensile strength of 790 MPa (115 ksi) — stronger than 97% of copper alloy grades. Strength varies by condition: see the 9 listed tempers.
Is C64800-TH04 easy to machine?
Not especially — machinability is rated fair (38/100, better than 55% of copper alloy grades). Machines like other silicon bronzes — gummy, ~30 % of AISI 1212; use sharp positive-rake tools, high speed, generous coolant, and machine in the aged condition for better chip control.
Can C64800-TH04 be welded?
With care — weldability is rated fair (50/100). GTAW/resistance and laser welding are feasible with silicon-bronze filler, but the aged strength is lost in the HAZ, so re-age or design joints away from spring sections; remove silica film before welding.
What surface finishes work on C64800-TH04?
No anodizing; tin, nickel or gold plating for contacts (nickel underplate recommended), and it polishes well or can be chemically patinated for decorative use.
Can C64800-TH04 be formed, bent or molded?
Do heavy drawing, coiling and bending in the solution-treated or partly cold-worked state, then age at ~450–500 °C for strength recovery and springback stabilization.
What is the maximum service temperature of C64800-TH04?
C64800-TH04 is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C64800-TF00 and C64800-O60?
TF00 is the default condition — standard stocked condition: best combination of strength, conductivity and stability after aging. O60: softest condition for maximum drawability or deep forming before hardening. Yield strength is 590 MPa in TF00 versus 140 MPa in O60.
Sources
- UNS/CDA copper alloy designation registration (C6xxxx silicon bronzes) — Copper Development Association (2023)
- ASM Handbook Vol. 2: Properties and Selection — Nonferrous Alloys — ASM International (1990)
- ASTM B601 — Temper Designations for Copper and Copper Alloys — ASTM (2019)
- copper.org alloy property database (silicon and nickel-silicon bronzes) — CDA (2024)
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.