Copper Alloy C42500-H04
Supply condition
UNS C42500 · EN CW454K
H04 = full hard
Standard high-strength connector strip temper for flat springs with bends across the rolling direction only.
Values for the H04 condition
Other C42500 tempers and conditions
C42500 is listed in 9 conditions; see the grade overview at C42500.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed to 0.035 mm grain size | Softest commercial strip temper; choose for deep drawing and severe forming before final stress relief. | 125 | 330 | 46 | 50 HRB | 28 % IACS |
Annealed to 0.015 mm grain size | Fine-grain anneal for formed parts needing a smooth surface after drawing (less orange peel) with slightly higher strength. | 150 | 360 | 42 | 58 HRB | 28 % IACS |
Quarter hard | Light cold work for parts that still need moderate bending but higher stiffness than annealed strip. | 305 | 400 | 25 | 68 HRB | 28 % IACS |
H02Default Half hard | Best all-round stocked strip temper: good balance of formability for stamped contacts and useful spring load. | 400 | 450 | 12 | 76 HRB | 28 % IACS |
Three-quarter hard | Choose when higher contact force is needed and only gentle, generous-radius bends are required. | 450 | 490 | 8 | 82 HRB | 28 % IACS |
H04This page Full hard | Standard high-strength connector strip temper for flat springs with bends across the rolling direction only. | 490 | 525 | 5 | 85 HRB | 28 % IACS |
Extra hard | For high-force, low-deflection springs and stamped blades where forming is limited to shallow bends. | 525 | 565 | 4 | 88 HRB | 28 % IACS |
Spring hard | Spring-quality strip for contact fingers and clips needing maximum elastic limit with minimal forming. | 565 | 600 | 3 | 91 HRB | 28 % IACS |
Extra spring hard | Maximum-strength strip for flat springs and shims; essentially no bending capability along the rolling direction. | 590 | 625 | 2 | 93 HRB | 28 % IACS |
What is C42500-H04?
C42500-H04 is C42500 supplied in the H04 condition — standard high-strength connector strip temper for flat springs with bends across the rolling direction only. C42500-H04 has a yield strength of 490 MPa (71.1 ksi) and a tensile strength of 525 MPa (76.1 ksi) — stronger than 88% of copper alloy grades. Elongation at break is 5% and the elastic modulus is 110 GPa (16 Msi). C42500-H04 has a density of 8.78 g/cm³ (0.317 lb/in³), heavier than 53% of copper alloy grades. It melts at 990°C (1,814 °F). H02 is the default condition FabDigit quotes; H04 is available on request or by drawing note.
Advantages
- High strength — 490 MPa (71.1 ksi), better than 88% of copper alloy grades
Limitations
- Limited ductility — 5%, worse than 93% of copper alloy grades
- Limited service temperature — 170°C (338 °F), worse than 92% of copper alloy grades
C42500-H04 properties
Typical room-temperature values for C42500-H04; 11 are specific to this condition. Other listed values are C42500 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C42500-H04 has a density of 8.78 g/cm³ (0.317 lb/in³), heavier than 53% of copper alloy grades. It melts at 990°C (1,814 °F).
Mechanical12
C42500-H04 has a yield strength of 490 MPa (71.1 ksi) and a tensile strength of 525 MPa (76.1 ksi) — stronger than 88% of copper alloy grades. Elongation at break is 5% and the elastic modulus is 110 GPa (16 Msi).
Thermal6
C42500-H04 is rated for continuous service to 170°C (338 °F). It conducts heat at 121 W/m·K (69.9 BTU/hr·ft·°F), better than 68% of copper alloy grades. Thermal expansion is 20.2 µm/m·K (11.2 µin/in·°F).
Electrical3
C42500-H04 conducts electricity at 28 % IACS, better than 69% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (60/100), worse than 68% of copper alloy grades.
Sustainability4
Producing a kilogram of C42500-H04 takes about 60 MJ of energy and emits 4 kg of CO₂ — more than 69% of copper alloy grades. Typical recycled content is 40%.
Manufacturability8
C42500-H04's machinability is poor (32/100, worse than 57% of copper alloy grades); weldability fair (45/100); formability poor (32/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C42500-H04
Is C42500 easy to machine?
Machinability about 30% of free-cutting brass — use sharp positive-rake tools, high speed and light feeds; strip parts are normally stamped rather than machined.
Can C42500 be welded?
Resistance and laser welding of thin strip are practical; fusion welding is fair at best due to zinc fume and porosity — soldering or brazing is preferred.
Can C42500 be formed, bent or molded?
Excellent stamping/drawing in OS or H01–H02 tempers; in H04 and harder, bend across the rolling direction with generous radii (≥2t) to avoid cracking.
What surface finishes work on C42500?
Solders and brazes very well; commonly tin-, nickel- or gold-plated for contacts; not anodizable, and stress-relieve formed parts to prevent season cracking before plating.
C42500 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 |
|---|---|---|
| Cusilver may be counted as copper | 87 – 90 | 88.5 |
| Sn | 1.5 – 3 | 2 |
| P0.35 % max, added as deoxidizer | 0.35 | 0.1 |
| Pbimpurity limit | ≤ 0.05 | — |
| Feimpurity limit | ≤ 0.05 | — |
| Znremainder, ≈9–10 % | balance | — |
C42500-H04 — frequently asked
What is C42500-H04 used for?
C42500-H04 is typically used for electrical connectors, springs and relay parts. In short: higher-strength tin brass; spring-temper connector strip; 28% IACS conductivity.
What is the yield strength of C42500-H04?
C42500-H04 has a typical yield strength of 490 MPa (71.1 ksi) and a tensile strength of 525 MPa (76.1 ksi) — stronger than 88% of copper alloy grades. Strength varies by condition: see the 9 listed tempers.
Is C42500-H04 easy to machine?
Not especially — machinability is rated poor (32/100, worse than 57% of copper alloy grades). Machinability about 30% of free-cutting brass — use sharp positive-rake tools, high speed and light feeds; strip parts are normally stamped rather than machined.
Can C42500-H04 be welded?
With care — weldability is rated fair (45/100). Resistance and laser welding of thin strip are practical; fusion welding is fair at best due to zinc fume and porosity — soldering or brazing is preferred.
What surface finishes work on C42500-H04?
Solders and brazes very well; commonly tin-, nickel- or gold-plated for contacts; not anodizable, and stress-relieve formed parts to prevent season cracking before plating.
Can C42500-H04 be formed, bent or molded?
Excellent stamping/drawing in OS or H01–H02 tempers; in H04 and harder, bend across the rolling direction with generous radii (≥2t) to avoid cracking.
What is the maximum service temperature of C42500-H04?
C42500-H04 is rated for continuous use to about 170°C (338 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C42500-H02 and C42500-OS035?
H02 is the default condition — best all-round stocked strip temper: good balance of formability for stamped contacts and useful spring load. OS035: softest commercial strip temper; choose for deep drawing and severe forming before final stress relief. Yield strength is 400 MPa in H02 versus 125 MPa in OS035.
Sources
- ASTM B591 — Copper-Zinc-Tin Alloy Plate, Sheet, Strip and Rolled Bar — ASTM International (2022)
- CDA Alloy C42500 property sheet — Copper Development Association (copper.org) (2023)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- EN 1652 / CW454K wrought copper alloy sheet and strip — CEN (1997)
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.