Copper Alloy C72700-TH04
Precip hard
UNS C72700
TH04 = tD04 and precipitation hardened
Maximum-strength aged strip for highly loaded flat springs where only gentle bends are formed.
Values for the TH04 condition
Other C72700 tempers and conditions
C72700 is listed in 9 conditions; see the grade overview at C72700.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution heat treated | Softest, most formable condition; choose when deep forming or heavy coining precedes a customer spinodal age. | 240 | 480 | 35 | 72 HRB | 9 % IACS |
Solution heat treated and cold worked, quarter hard | Light cold work for formed parts that will be spinodal aged (to TH01) after stamping. | 450 | 560 | 15 | 166 HB | 9 % IACS |
Solution heat treated and cold worked, half hard | Balanced strength/bendability strip for stamped springs that receive a post-form age. | 550 | 620 | 9 | 91 HRB | 9 % IACS |
Solution heat treated and cold worked, full hard | Hard cold-rolled strip for flat springs and contacts where only simple bends are needed before aging. | 680 | 720 | 4 | 96 HRB | 9 % IACS |
TH01Default TD01 and precipitation hardened | Most commonly stocked mill-hardened strip: high spring strength with usable bend formability and no post-form heat treatment. | 730 | 800 | 8 | 23 HRC | 11 % IACS |
Mill hardened, full hard | Producer-controlled mill-hardened temper balancing formability and yield strength for connector stamping lines. | 790 | 840 | 8 | 25 HRC | 11 % IACS |
TD02 and precipitation hardened | Higher-strength mill-hardened temper for compact contacts with moderate bend requirements. | 810 | 870 | 6 | 26 HRC | 11 % IACS |
TH04This page TD04 and precipitation hardened | Maximum-strength aged strip for highly loaded flat springs where only gentle bends are formed. | 900 | 950 | 4 | 29 HRC | 11 % IACS |
Mill hardened, spring hard | Top mill-hardened strength level for miniature high-force contacts; formability is limited to gentle bends. | 950 | 1,000 | 4 | 30 HRC | 11 % IACS |
What is C72700-TH04?
C72700-TH04 is C72700 in the TH04 condition — maximum-strength aged strip for highly loaded flat springs where only gentle bends are formed. C72700-TH04 has a yield strength of 900 MPa (131 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 98% of copper alloy grades. Elongation at break is 4% and the elastic modulus is 132 GPa (19.1 Msi). C72700-TH04 has a density of 8.86 g/cm³ (0.32 lb/in³), heavier than 68% of copper alloy grades. It melts at 1,060°C (1,940 °F). TH01 is the default condition FabDigit quotes; TH04 is available on request or by drawing note.
Advantages
- High strength — 900 MPa (131 ksi), better than 98% of copper alloy grades
- Stiff — 132 GPa (19.1 Msi), better than 93% of copper alloy grades
- Good corrosion resistance — 72/100, better than 84% of copper alloy grades
Limitations
- Limited ductility — 4%, worse than 96% of copper alloy grades
- Poor heat conductor — 33 W/m·K (19.1 BTU/hr·ft·°F), worse than 89% of copper alloy grades
- High embodied carbon — 4.8 kg CO₂/kg, worse than 84% of copper alloy grades
C72700-TH04 properties
Typical room-temperature values for C72700-TH04; 22 are specific to this condition. Other listed values are C72700 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C72700-TH04 has a density of 8.86 g/cm³ (0.32 lb/in³), heavier than 68% of copper alloy grades. It melts at 1,060°C (1,940 °F).
Mechanical12
C72700-TH04 has a yield strength of 900 MPa (131 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 98% of copper alloy grades. Elongation at break is 4% and the elastic modulus is 132 GPa (19.1 Msi).
Thermal6
C72700-TH04 is rated for continuous service to 200°C (392 °F). It conducts heat at 33 W/m·K (19.1 BTU/hr·ft·°F), worse than 89% of copper alloy grades. Thermal expansion is 16.5 µm/m·K (9.17 µin/in·°F).
Electrical3
C72700-TH04 conducts electricity at 11 % IACS, worse than 68% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is very good (72/100), better than 84% of copper alloy grades.
Sustainability4
Producing a kilogram of C72700-TH04 takes about 68 MJ of energy and emits 4.8 kg of CO₂ — more than 83% of copper alloy grades. Typical recycled content is 25%.
Manufacturability7
C72700-TH04's machinability is poor (32/100, worse than 57% of copper alloy grades); weldability poor (32/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C72700-TH04
Is C72700 easy to machine?
Machines like a tough Cu-Ni: ~20 % of free-cutting brass, use sharp carbide, positive rake, generous coolant and heavier feeds to avoid work hardening; aged tempers cut with better chip control than annealed.
Can C72700 be welded?
Resistance and laser welding are practical; fusion welding softens the aged spinodal structure in the HAZ, so join before aging or accept local strength loss — solders and silver brazes wet the alloy well.
Can C72700 be formed, bent or molded?
Form in TB00/TD01 for deep or tight bends then spinodal age (typically ~350–400 °C, several hours) for peak strength; mill-hardened TH/TM tempers allow only moderate bends, mostly good-way.
What surface finishes work on C72700?
Not anodizable — plate with Ni underlayer plus Sn, Ag or Au for contacts; takes a bright polish and forms a stable dull-bronze oxide in service.
C72700 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 |
|---|---|---|
| Ni | 8.5 – 9.5 | 9 |
| Sn | 5.5 – 6.5 | 6 |
| Mndeoxidizer/grain control | 0.05 – 0.3 | 0.15 |
| Mg | ≤ 0.15 | — |
| Nbmax, grain refiner | ≤ 0.1 | — |
| Fe | ≤ 0.5 | — |
| Zn | ≤ 0.5 | — |
| Pb | ≤ 0.02 | — |
| Curemainder, nominally ~84 % | balance | — |
C72700-TH04 — frequently asked
What is C72700-TH04 used for?
C72700-TH04 is typically used for high-reliability connectors, springs and electronic contacts. In short: spinodal-hardened Cu-Ni-Sn; stronger than C72500; beryllium-free contact alloy.
What is the yield strength of C72700-TH04?
C72700-TH04 has a typical yield strength of 900 MPa (131 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 98% of copper alloy grades. Strength varies by condition: see the 9 listed tempers.
Is C72700-TH04 easy to machine?
Not especially — machinability is rated poor (32/100, worse than 57% of copper alloy grades). Machines like a tough Cu-Ni: ~20 % of free-cutting brass, use sharp carbide, positive rake, generous coolant and heavier feeds to avoid work hardening; aged tempers cut with better chip control than annealed.
Can C72700-TH04 be welded?
Not readily — weldability is rated poor (32/100). Resistance and laser welding are practical; fusion welding softens the aged spinodal structure in the HAZ, so join before aging or accept local strength loss — solders and silver brazes wet the alloy well.
What surface finishes work on C72700-TH04?
Not anodizable — plate with Ni underlayer plus Sn, Ag or Au for contacts; takes a bright polish and forms a stable dull-bronze oxide in service.
Can C72700-TH04 be formed, bent or molded?
Form in TB00/TD01 for deep or tight bends then spinodal age (typically ~350–400 °C, several hours) for peak strength; mill-hardened TH/TM tempers allow only moderate bends, mostly good-way.
What is the maximum service temperature of C72700-TH04?
C72700-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 C72700-TH01 and C72700-TB00?
TH01 is the default condition — most commonly stocked mill-hardened strip: high spring strength with usable bend formability and no post-form heat treatment. TB00: softest, most formable condition; choose when deep forming or heavy coining precedes a customer spinodal age. Yield strength is 730 MPa in TH01 versus 240 MPa in TB00.
Sources
- ASTM B740 — Copper-Nickel-Tin Spinodal Alloy Strip — ASTM International (2020)
- CDA Standard Designations for Wrought Copper Alloys (C72700) — Copper Development Association (2023)
- BrushForm 725 / Cu-9Ni-6Sn strip data — Materion (2022)
- ASM Handbook Vol. 2 — Properties of Copper and Copper 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.