Copper Alloy C19025-HR04
Temper · default condition
UNS C19025
HR04 = full hard and stress relieved
The workhorse connector-strip temper: balanced spring force, bendability and stress-relaxation resistance.
Values for the HR04 condition
Other C19025 tempers and conditions
C19025 is listed in 7 conditions; see the grade overview at C19025.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Soft annealed | Pick for deep-drawn or severely formed parts where strength is added later by the customer's own work hardening. | 180 | 380 | 25 | 105 HB | 48 % IACS |
Half hard | Cold-rolled half hard strip for forming-dominated parts that do not need the extra relaxation resistance of a stress-relief bake. | 430 | 500 | 10 | 148 HB | 43 % IACS |
Half hard and stress relieved | Choose when tight bends (small bend radii, complex terminal geometry) matter more than peak spring force. | 480 | 520 | 9 | 83 HRB | 46 % IACS |
Full hard | Straight cold-rolled hard strip; cheaper than the HR grades but with lower stress-relaxation resistance. | 510 | 565 | 6 | 166 HB | 42 % IACS |
HR04DefaultThis page Full hard and stress relieved | The workhorse connector-strip temper: balanced spring force, bendability and stress-relaxation resistance. | 550 | 585 | 6 | 88 HRB | 45 % IACS |
Extra hard and stress relieved | Highest-strength stocked temper for miniature high-force contacts; bend radii must be generous and grain direction respected. | 610 | 635 | 4 | 92 HRB | 44 % IACS |
Spring hard and stress relieved | Special-order spring temper for flat contact springs where formability is minimal but contact force must be maximal. | 655 | 680 | 3 | 14 HRC | 43 % IACS |
What is C19025-HR04?
C19025-HR04 is C19025 in the HR04 temper — the workhorse connector-strip temper: balanced spring force, bendability and stress-relaxation resistance. C19025-HR04 has a yield strength of 550 MPa (79.8 ksi) and a tensile strength of 585 MPa (84.8 ksi) — stronger than 92% of copper alloy grades. Elongation at break is 6% and the elastic modulus is 125 GPa (18.1 Msi). C19025-HR04 has a density of 8.9 g/cm³ (0.322 lb/in³), heavier than 77% of copper alloy grades. It melts at 1,070°C (1,958 °F).
Advantages
- High strength — 550 MPa (79.8 ksi), better than 92% of copper alloy grades
- High electrical conductivity — 45 % IACS, better than 77% of copper alloy grades
- Conducts heat well — 180 W/m·K (104 BTU/hr·ft·°F), better than 75% of copper alloy grades
Limitations
- Limited ductility — 6%, worse than 89% of copper alloy grades
C19025-HR04 properties
Typical room-temperature values for C19025-HR04; 14 are specific to this condition. Other listed values are C19025 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C19025-HR04 has a density of 8.9 g/cm³ (0.322 lb/in³), heavier than 77% of copper alloy grades. It melts at 1,070°C (1,958 °F).
Mechanical11
C19025-HR04 has a yield strength of 550 MPa (79.8 ksi) and a tensile strength of 585 MPa (84.8 ksi) — stronger than 92% of copper alloy grades. Elongation at break is 6% and the elastic modulus is 125 GPa (18.1 Msi).
Thermal6
C19025-HR04 is rated for continuous service to 180°C (356 °F). It conducts heat at 180 W/m·K (104 BTU/hr·ft·°F), better than 75% of copper alloy grades. Thermal expansion is 17.5 µm/m·K (9.72 µin/in·°F).
Electrical3
C19025-HR04 conducts electricity at 45 % IACS, better than 77% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 57% of copper alloy grades.
Sustainability4
Producing a kilogram of C19025-HR04 takes about 57 MJ of energy and emits 3.9 kg of CO₂ — less than 52% of copper alloy grades. Typical recycled content is 30%.
Manufacturability7
C19025-HR04's machinability is poor (30/100, worse than 67% of copper alloy grades); weldability fair (45/100); formability fair (45/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C19025-HR04
Is C19025 easy to machine?
Gummy, non-leaded copper alloy — use sharp positive-rake carbide, high speed and flood coolant; mostly stamped rather than machined.
Can C19025 be welded?
Resistance and laser spot welding are practical; any fusion welding locally anneals the cold-worked temper and drops contact force.
Can C19025 be formed, bent or molded?
Progressive-die stamping of thin strip; bend with grain direction in mind (GW ≈ 0.3–0.5 t at HR02, ≥1 t at HR06) and stress-relief bake after severe forming.
What surface finishes work on C19025?
Not anodisable — standard finishes are reflow/matte tin, nickel underplate with gold or silver flash for contact surfaces.
C19025 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 |
|---|---|---|
| Niprincipal strengthener with Sn/P | 0.8 – 1.8 | 1 |
| Snsolid-solution strengthening, improves stress relaxation | 0.5 – 1.5 | 0.9 |
| Pforms Ni-P precipitates, deoxidiser | 0.01 – 0.15 | 0.05 |
| Znimpurity limit | ≤ 0.2 | — |
| Feimpurity limit | ≤ 0.1 | — |
| Cu96.0 % min including Ag; balance | balance | — |
C19025-HR04 — frequently asked
What is C19025-HR04 used for?
C19025-HR04 is typically used for automotive connectors, electronic terminals and battery contacts. In short: high-strength connector strip; stronger than C19020; 45 % IACS spring copper.
What is the yield strength of C19025-HR04?
C19025-HR04 has a typical yield strength of 550 MPa (79.8 ksi) and a tensile strength of 585 MPa (84.8 ksi) — stronger than 92% of copper alloy grades. Strength varies by condition: see the 7 listed tempers.
Is C19025-HR04 easy to machine?
Not especially — machinability is rated poor (30/100, worse than 67% of copper alloy grades). Gummy, non-leaded copper alloy — use sharp positive-rake carbide, high speed and flood coolant; mostly stamped rather than machined.
Can C19025-HR04 be welded?
With care — weldability is rated fair (45/100). Resistance and laser spot welding are practical; any fusion welding locally anneals the cold-worked temper and drops contact force.
What surface finishes work on C19025-HR04?
Not anodisable — standard finishes are reflow/matte tin, nickel underplate with gold or silver flash for contact surfaces.
Can C19025-HR04 be formed, bent or molded?
Progressive-die stamping of thin strip; bend with grain direction in mind (GW ≈ 0.3–0.5 t at HR02, ≥1 t at HR06) and stress-relief bake after severe forming.
What is the maximum service temperature of C19025-HR04?
C19025-HR04 is rated for continuous use to about 180°C (356 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C19025-HR04 and C19025-O60?
HR04 is the default condition — the workhorse connector-strip temper: balanced spring force, bendability and stress-relaxation resistance. O60: pick for deep-drawn or severely formed parts where strength is added later by the customer's own work hardening. Yield strength is 550 MPa in HR04 versus 180 MPa in O60.
Sources
- ASTM B888/B888M — Copper Alloy Strip for Use in Manufacture of Electrical Connectors or Spring Contacts — ASTM International (2020)
- CDA Alloy Registration — C19025 (Cu-Ni-Sn-P) — Copper Development Association (2022)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- High-performance Cu-Ni-Sn-P connector strip (KLF-118 class) datasheet — Copper strip producer (2021)
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.