Copper Alloy QBe0.4-TH04
Precip hard
GB QBe0.4
TH04 = tD04 and precipitation hardened
Highest strength available in QBe0.4 — flat springs and heavily loaded contacts.
Values for the TH04 condition
Other QBe0.4 tempers and conditions
QBe0.4 is listed in 13 conditions; see the grade overview at QBe0.4.
Compare all 13 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution heat treated | Softest, most formable condition for deep drawing or complex stamping before customer-side aging. | 200 | 380 | 35 | 90 HB | 25 % IACS |
Solution heat treated and cold worked, quarter hard | Lightly cold-worked feedstock for forming followed by precipitation aging. | 350 | 450 | 20 | 120 HB | 25 % IACS |
Mill hardened | Softest mill-hardened strip: form complex shapes with no further heat treatment. | 415 | 550 | 20 | 150 HB | 55 % IACS |
Solution heat treated and cold worked, half hard | Medium cold work before aging; balance of formability and post-age strength. | 430 | 500 | 12 | 140 HB | 25 % IACS |
Solution heat treated and cold worked, full hard | Maximum cold work before aging; gives the highest attainable aged strength. | 510 | 570 | 6 | 165 HB | 25 % IACS |
Solution heat treated and precipitation hardened | Aged from the fully soft condition — best choice when the part is deep-formed first and then hardened. | 550 | 690 | 15 | 185 HB | 50 % IACS |
Mill hardened, half hard | Mid-range mill-hardened strip for connectors needing both bendability and spring force. | 550 | 655 | 15 | 180 HB | 52 % IACS |
TM04Default Mill hardened, full hard | Most widely stocked QBe0.4 strip: ~50% IACS with 700+ MPa strength, no customer heat treatment. | 655 | 760 | 12 | 95 HRB | 50 % IACS |
TD01 and precipitation hardened | Aged after light cold work — moderate strength with retained ductility. | 655 | 740 | 11 | 200 HB | 50 % IACS |
Mill hardened, extra hard | High-strength mill-hardened strip for small-radius, high-force contact springs. | 690 | 795 | 10 | 22 HRC | 48 % IACS |
TD02 and precipitation hardened | Common spring-contact condition where higher yield is needed than TF00. | 720 | 790 | 8 | 22 HRC | 50 % IACS |
TH04This page TD04 and precipitation hardened | Highest strength available in QBe0.4 — flat springs and heavily loaded contacts. | 760 | 830 | 6 | 25 HRC | 48 % IACS |
Mill hardened, spring hard | Strongest mill-hardened QBe0.4 strip; use only for gentle bends and flat spring blanks. | 760 | 850 | 8 | 25 HRC | 46 % IACS |
What is QBe0.4-TH04?
QBe0.4-TH04 is QBe0.4 in the TH04 condition — highest strength available in QBe0.4 — flat springs and heavily loaded contacts. QBe0.4-TH04 has a yield strength of 760 MPa (110 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 98% of copper alloy grades. Elongation at break is 6% and the elastic modulus is 138 GPa (20 Msi). QBe0.4-TH04 has a density of 8.83 g/cm³ (0.319 lb/in³), heavier than 65% of copper alloy grades. It melts at 1,030°C (1,886 °F). TM04 is the default condition FabDigit quotes; TH04 is available on request or by drawing note.
Advantages
- High strength — 760 MPa (110 ksi), better than 98% of copper alloy grades
- Stiff — 138 GPa (20 Msi), better than 95% of copper alloy grades
- Conducts heat well — 200 W/m·K (115.6 BTU/hr·ft·°F), better than 78% of copper alloy grades
- High electrical conductivity — 48 % IACS, better than 78% of copper alloy grades
Limitations
- High embodied carbon — 6.5 kg CO₂/kg, worse than 94% of copper alloy grades
- Limited ductility — 6%, worse than 89% of copper alloy grades
QBe0.4-TH04 properties
Typical room-temperature values for QBe0.4-TH04; 23 are specific to this condition. Other listed values are QBe0.4 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
QBe0.4-TH04 has a density of 8.83 g/cm³ (0.319 lb/in³), heavier than 65% of copper alloy grades. It melts at 1,030°C (1,886 °F).
Mechanical12
QBe0.4-TH04 has a yield strength of 760 MPa (110 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 98% of copper alloy grades. Elongation at break is 6% and the elastic modulus is 138 GPa (20 Msi).
Thermal5
QBe0.4-TH04 is rated for continuous service to 200°C (392 °F). It conducts heat at 200 W/m·K (115.6 BTU/hr·ft·°F), better than 78% of copper alloy grades. Thermal expansion is 17.5 µm/m·K (9.72 µin/in·°F).
Electrical3
QBe0.4-TH04 conducts electricity at 48 % IACS, better than 78% 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 QBe0.4-TH04 takes about 95 MJ of energy and emits 6.5 kg of CO₂ — more than 95% of copper alloy grades. Typical recycled content is 30%.
Manufacturability7
QBe0.4-TH04's machinability is fair (50/100, better than 69% of copper alloy grades); weldability fair (38/100); formability poor (30/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with QBe0.4-TH04
Is QBe0.4 easy to machine?
Machines like a hard bronze — carbide tooling, positive rake, flood coolant; beryllium-containing chips and dust require local exhaust and wet collection, never dry grinding.
Can QBe0.4 be welded?
Resistance and laser welding are routine; TIG/EBW possible with matching or Cu-Ni filler, but aged strength drops in the HAZ and re-aging (315 °C/2 h) is advised.
Can QBe0.4 be formed, bent or molded?
Form in TB00/TD or the softer mill-hardened tempers; bend transverse to rolling direction where possible, and age 315–345 °C for 2–3 h to develop full strength with only slight dimensional change.
What surface finishes work on QBe0.4?
Takes bright polish and accepts Ni/Au/Sn/Ag plating for connectors; do not anodize — degrease and lightly acid-activate before plating to remove the beryllium-oxide film.
QBe0.4 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 |
|---|---|---|
| Below-beryllium precipitation hardener | 0.15 – 0.5 | 0.35 |
| Cograin refiner / co-precipitate | 0.35 – 0.6 | 0.5 |
| Nimay substitute part of Co in some mill practice | ≤ 0.2 | — |
| Feimpurity limit | ≤ 0.2 | — |
| Siimpurity limit | ≤ 0.2 | — |
| Alimpurity limit | ≤ 0.2 | — |
| Pbimpurity limit | ≤ 0.02 | — |
| CuCu + named elements ≥ 99.5 % | balance | — |
QBe0.4-TH04 — frequently asked
What is QBe0.4-TH04 used for?
QBe0.4-TH04 is typically used for electrical connectors, relay contacts and switch springs. In short: high-conductivity beryllium copper; 50 % IACS spring alloy; milder alternative to C17200.
What is the yield strength of QBe0.4-TH04?
QBe0.4-TH04 has a typical yield strength of 760 MPa (110 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 98% of copper alloy grades. Strength varies by condition: see the 13 listed tempers.
Is QBe0.4-TH04 easy to machine?
Reasonably — machinability is rated fair (50/100, better than 69% of copper alloy grades). Machines like a hard bronze — carbide tooling, positive rake, flood coolant; beryllium-containing chips and dust require local exhaust and wet collection, never dry grinding.
Can QBe0.4-TH04 be welded?
With care — weldability is rated fair (38/100). Resistance and laser welding are routine; TIG/EBW possible with matching or Cu-Ni filler, but aged strength drops in the HAZ and re-aging (315 °C/2 h) is advised.
What surface finishes work on QBe0.4-TH04?
Takes bright polish and accepts Ni/Au/Sn/Ag plating for connectors; do not anodize — degrease and lightly acid-activate before plating to remove the beryllium-oxide film.
Can QBe0.4-TH04 be formed, bent or molded?
Form in TB00/TD or the softer mill-hardened tempers; bend transverse to rolling direction where possible, and age 315–345 °C for 2–3 h to develop full strength with only slight dimensional change.
What is the maximum service temperature of QBe0.4-TH04?
QBe0.4-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 QBe0.4-TM04 and QBe0.4-TB00?
TM04 is the default condition — most widely stocked QBe0.4 strip: ~50% IACS with 700+ MPa strength, no customer heat treatment. TB00: softest, most formable condition for deep drawing or complex stamping before customer-side aging. Yield strength is 655 MPa in TM04 versus 200 MPa in TB00.
Sources
- ASTM B768 — Copper-Beryllium Alloy Strip (UNS C17410 etc.) — ASTM International (2021)
- Alloy 174 (C17410) High Conductivity Copper Beryllium Strip — Materion Brush Performance Alloys (2020)
- CDA Alloy Database — UNS C17410 — Copper Development Association (2023)
- 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.