Copper Alloy TU1-O25
Temper
GB TU1 · ASTM B170 · EN CW008A, Cu-OFE · JIS C1011
O25 = hot rolled and annealed
Soft plate/forging stock condition for machined UHV chambers, waveguides and heavy conductors.
Values for the O25 condition
Other TU1 tempers and conditions
TU1 is listed in 13 conditions; see the grade overview at TU1.
Compare all 13 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
O25This page Hot rolled and annealed | Soft plate/forging stock condition for machined UHV chambers, waveguides and heavy conductors. | 62 | 220 | 48 | 42 HB | 101 % IACS |
OS050Default Annealed to 0.050 mm grain size | Standard stocked soft condition for deep drawing, forming, vacuum-brazed and UHV parts. | 69 | 221 | 45 | 45 HB | 101 % IACS |
Annealed to 0.025 mm grain size | Fine-grain annealed strip for thin-gauge stamping where orange-peel must be avoided. | 83 | 234 | 42 | 50 HB | 101 % IACS |
As hot rolled | Mill hot-rolled bar/plate for parts that will be machined and later annealed or brazed. | 90 | 235 | 40 | 50 HB | 101 % IACS |
1/8 hard | Slight cold work for improved flatness and handling stiffness while keeping good formability. | 160 | 234 | 30 | 55 HB | 101 % IACS |
Light drawn | Lightly drawn rod/tube giving straightness and modest strength while retaining bendability. | 200 | 262 | 25 | 65 HB | 101 % IACS |
Quarter hard | Best compromise of stiffness and bendability for stamped busbars, clips and shields. | 205 | 262 | 25 | 60 HB | 101 % IACS |
Half hard | Most common semi-rigid strip/bar temper for busbar, terminals and gaskets needing some springback. | 250 | 290 | 14 | 75 HB | 101 % IACS |
Full hard | Rigid strip/sheet for flat springs, contacts and stiff conductors where only mild forming is needed. | 310 | 345 | 6 | 90 HB | 100 % IACS |
Extra hard | High-strength strip for flat springs and contact blades with minimal forming. | 345 | 379 | 4 | 95 HB | 100 % IACS |
Hard drawn | Fully hard-drawn rod/wire for overhead and high-strength conductors, commutator bars and machined parts. | 345 | 379 | 10 | 100 HB | 100 % IACS |
Spring hard | Spring-tempered strip for high-conductivity contact springs and EMI fingerstock. | 365 | 393 | 4 | 100 HB | 100 % IACS |
Extra spring hard | Maximum cold-rolled strength of the strip series; only flat or very gentle forms. | 372 | 400 | 4 | 105 HB | 100 % IACS |
What is TU1-O25?
TU1-O25 is TU1 in the O25 temper — soft plate/forging stock condition for machined UHV chambers, waveguides and heavy conductors. TU1-O25 has a yield strength of 62 MPa (8.99 ksi) and a tensile strength of 220 MPa (31.9 ksi) — weaker than 99% of copper alloy grades. Elongation at break is 48% and the elastic modulus is 115 GPa (16.7 Msi). TU1-O25 has a density of 8.94 g/cm³ (0.323 lb/in³), heavier than 90% of copper alloy grades. It melts at 1,083°C (1,981 °F). OS050 is the default condition FabDigit quotes; O25 is available on request or by drawing note.
Advantages
- Conducts heat well — 391 W/m·K (225.9 BTU/hr·ft·°F), better than 98% of copper alloy grades
- High electrical conductivity — 101 % IACS, better than 98% of copper alloy grades
- Ductile — tolerates forming and impact — 48%, better than 97% of copper alloy grades
- Forms and bends easily — 93/100, better than 92% of copper alloy grades
- Polishes to a fine finish — 85/100, better than 92% of copper alloy grades
Limitations
- Low strength — 62 MPa (8.99 ksi), worse than 99% of copper alloy grades
TU1-O25 properties
Typical room-temperature values for TU1-O25; 10 are specific to this condition. Other listed values are TU1 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
TU1-O25 has a density of 8.94 g/cm³ (0.323 lb/in³), heavier than 90% of copper alloy grades. It melts at 1,083°C (1,981 °F).
Mechanical11
TU1-O25 has a yield strength of 62 MPa (8.99 ksi) and a tensile strength of 220 MPa (31.9 ksi) — weaker than 99% of copper alloy grades. Elongation at break is 48% and the elastic modulus is 115 GPa (16.7 Msi).
Thermal6
TU1-O25 is rated for continuous service to 250°C (482 °F). It conducts heat at 391 W/m·K (225.9 BTU/hr·ft·°F), better than 98% of copper alloy grades. Thermal expansion is 17 µm/m·K (9.44 µin/in·°F).
Electrical3
TU1-O25 conducts electricity at 101 % IACS, better than 98% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (60/100), worse than 68% of copper alloy grades.
Sustainability4
Producing a kilogram of TU1-O25 takes about 60 MJ of energy and emits 4 kg of CO₂ — more than 69% of copper alloy grades. Typical recycled content is 15%.
Manufacturability8
TU1-O25's machinability is poor (28/100, worse than 78% of copper alloy grades); weldability very good (70/100); formability excellent (93/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with TU1-O25
Is TU1 easy to machine?
Gummy and stringy — use sharp, high-positive-rake carbide or PCD tools, high speed with low feed, generous flood coolant; expect ~20% of AISI 1212 productivity, avoid work-hardened rubbing.
Can TU1 be welded?
Excellent for TIG/EB/laser and vacuum brazing because there is no oxygen to cause hydrogen embrittlement; preheat 200–500 °C on thick sections due to the very high thermal conductivity.
Can TU1 be formed, bent or molded?
Outstanding cold formability in OS050/O25 (deep draw, spin, coin); interanneal at 400–600 °C after roughly 50–70% reduction, hard tempers must be bent with generous radii along the grain.
What surface finishes work on TU1?
Not anodisable; mechanically polishes to a mirror and is commonly electroplated with Ni/Ag/Au or chemically cleaned/passivated (citric or dilute acid) for UHV service to control tarnish.
TU1 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 |
|---|---|---|
| O≤20 ppm for TU1; ≤5 ppm for C10100 (Cu-OFE) | ≤ 0 | 5×10⁻⁴ |
| P | ≤ 0 | — |
| Bi | ≤ 0 | — |
| Sb | ≤ 0 | — |
| As | ≤ 0 | — |
| Fe | ≤ 0 | — |
| Ni | ≤ 0 | — |
| Pb | ≤ 0 | — |
| Sn | ≤ 0 | — |
| Zn | ≤ 0 | — |
| S | ≤ 0 | — |
| CuCu+Ag per GB/T 5231 TU1; C10100 requires 99.99% min | ≥ 99.97 (balance) | — |
TU1-O25 — frequently asked
What is TU1-O25 used for?
TU1-O25 is typically used for vacuum electronics, high-conductivity conductors, waveguides and welding electrode tips. In short: highest-purity oxygen-free copper; no hydrogen embrittlement; vacuum and UHV grade.
What is the yield strength of TU1-O25?
TU1-O25 has a typical yield strength of 62 MPa (8.99 ksi) and a tensile strength of 220 MPa (31.9 ksi) — weaker than 99% of copper alloy grades. Strength varies by condition: see the 13 listed tempers.
Is TU1-O25 easy to machine?
Not especially — machinability is rated poor (28/100, worse than 78% of copper alloy grades). Gummy and stringy — use sharp, high-positive-rake carbide or PCD tools, high speed with low feed, generous flood coolant; expect ~20% of AISI 1212 productivity, avoid work-hardened rubbing.
Can TU1-O25 be welded?
Yes — weldability is rated very good (70/100). Excellent for TIG/EB/laser and vacuum brazing because there is no oxygen to cause hydrogen embrittlement; preheat 200–500 °C on thick sections due to the very high thermal conductivity.
What surface finishes work on TU1-O25?
Not anodisable; mechanically polishes to a mirror and is commonly electroplated with Ni/Ag/Au or chemically cleaned/passivated (citric or dilute acid) for UHV service to control tarnish.
Can TU1-O25 be formed, bent or molded?
Outstanding cold formability in OS050/O25 (deep draw, spin, coin); interanneal at 400–600 °C after roughly 50–70% reduction, hard tempers must be bent with generous radii along the grain.
What is the maximum service temperature of TU1-O25?
TU1-O25 is rated for continuous use to about 250°C (482 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between TU1-OS050 and TU1-H10?
OS050 is the default condition — standard stocked soft condition for deep drawing, forming, vacuum-brazed and UHV parts. H10: maximum cold-rolled strength of the strip series; only flat or very gentle forms. Yield strength is 69 MPa in OS050 versus 372 MPa in H10.
Sources
- ASTM B170 Oxygen-Free Electrolytic Copper Refinery Shapes — ASTM (2019)
- ASTM B152/B152M Copper Sheet, Strip, Plate and Rolled Bar — ASTM (2019)
- CDA Alloy C10100 property datasheet — Copper Development Association (copper.org) (2023)
- ASM Handbook Vol. 2 — Properties of Nonferrous Alloys — ASM International (1990)
- EN 13601 / CW008A Cu-OFE — CEN (2013)
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.