High-Copper Alloys
High-copper alloys keep at least 96 % Cu and add a few percent of beryllium, chromium, zirconium, nickel-silicon or iron that precipitation-hardens the matrix. That buys strength no other copper alloy has — C17200 beryllium copper ages to 1,000–1,200 MPa yield, about the same as a quenched-and-tempered alloy steel — while conductivity stays between 20 and 80 % IACS. They are the springs, connectors, welding electrodes and mold inserts of the copper family.
Popular high-copper alloy grades
Compare in the explorer| Grade | Yield, MPa | Tensile, MPa | Density, g/cm³ | Machinability | Weldability | Best for |
|---|---|---|---|---|---|---|
| C17200 | 260 | 490 | 8.26 | Fair | Fair | Strongest springs, tooling, non-sparking tools |
| C17300 | 220 | 470 | 8.26 | Fair | Poor | Leaded beryllium copper for turned parts |
| C17510 | 170 | 310 | 8.75 | Poor | Good | Conductive springs and welding tips |
| C17500 | 620 | 760 | 8.75 | Fair | Good | Cobalt-beryllium electrodes and contacts |
| CuCrZr | 350 | 430 | 8.89 | Fair | Fair | Welding electrodes, printed combustion liners |
| C19400 | 370 | 420 | 8.91 | Poor | Fair | Lead frames and stamped connectors |
| C18700 | 275 | 315 | 8.94 | Excellent | Poor | Free-machining conductor, 96 % IACS |
Choose a high-copper alloy for
Spring contacts and connectors that flex for millions of cycles, resistance-welding electrodes and wheels, injection-mold cores and inserts that must pull heat, non-sparking and non-magnetic tools, and any conductor that also has to carry a real load or run hot.
Look elsewhere when
Only conductivity matters (C11000 is twice as conductive), the spring sees modest stress and volume is high (C51000 phosphor bronze costs far less), the part is a plain machined fitting (C36000 brass), or beryllium is forbidden by the customer — then C70250 or C72900 give 550–900 MPa without it.
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High-copper alloy by application
- Springs and contacts
- C17200 in a mill-hardened temper for stamped springs and battery contacts; C17510 when the spring carries current and heats up; C19400 strip for high-volume connectors where 65 % IACS matters more than strength.
- Resistance-welding electrodes
- C18200 and CuCrZr (RWMA Class 2) for spot-welding tips and seam wheels; C17510 (Class 3) where the tip must hold shape against hot galvanized or stainless sheet.
Working with high-copper alloy
- Machining
- Machine in the solution-annealed (A) or quarter-hard condition and age afterwards; aged C17200 at 36–42 HRC cuts at about a third of the speed. Aging shifts dimensions by a fraction of a percent, so leave finish stock on tight features. Beryllium-bearing alloys need dust extraction and wet grinding.
- Heat treatment
- C17200 ages 2–3 hours at 315–345 °C to TF00 (AT); C17510 and C17500 need 2–3 hours at 480 °C; CuCrZr and C18200 solution-treat at 980 °C and age 2–4 hours at 450–500 °C. Mill-hardened strip tempers (TM02–TM08) arrive ready and skip the in-house cycle.
- Forming
- Beryllium-copper strip forms in A, quarter-hard or half-hard and hardens after forming; mill-hardened strip bends to about 2 t radius and no tighter. Orient bends across the rolling direction where possible.
- Joining
- Silver-braze in the annealed condition and age afterwards — a 600–700 °C braze cycle softens an already-aged part. TIG welding is possible on CuCrZr with matching filler; beryllium-copper fume is hazardous, so welding is avoided in favour of brazing, resistance or laser joints.
Other copper alloy series
High-Copper Alloys — frequently asked
What is high-copper alloy?
High-copper alloys keep at least 96 % Cu and add a few percent of beryllium, chromium, zirconium, nickel-silicon or iron that precipitation-hardens the matrix. That buys strength no other copper alloy has — C17200 beryllium copper ages to 1,000–1,200 MPa yield, about the same as a quenched-and-tempered alloy steel — while conductivity stays between 20 and 80 % IACS. They are the springs, connectors, welding electrodes and mold inserts of the copper family.
Which grade of high-copper alloy should I use?
C17200 when the part must be as strong as steel: miniature springs, Bourdon tubes, high-cycle contacts, non-sparking tools, plastic-mold cores that need conductivity. C17300 is the same alloy with lead for screw-machine parts. C17510 and C17500 trade strength for conductivity (about 700 MPa at 45–60 % IACS) and are the choice for current-carrying springs, hot connectors and resistance-welding tips. CuCrZr and C18200 chromium copper for electrodes, seam-welding wheels and printed rocket-combustion liners — 80 % IACS at about 400 MPa yield, softening only above 500 °C. C19400 and the Cu-Fe-P strip alloys are the lead-frame and stamped-connector grades; C18700 leaded copper machines like brass at 96 % IACS.
Which grade of high-copper alloy is the strongest?
C17000 has the highest yield strength in the series at 1,000 MPa; C17410 follows at 690 MPa. Values are for each grade's default condition.
Which grade of high-copper alloy is easiest to machine?
C18700 (machinability excellent, 90/100), then C19100 (82/100).
Is high-copper alloy heat-treatable?
Yes. These grades gain their strength from heat treatment; the conditions and their properties are listed on each grade page.
C17200 or C17510 for a spring contact?
C17200 when stress and fatigue life set the design: 1,000–1,200 MPa yield in TF00, better than any other copper alloy, at 22 % IACS. C17510 when the contact also carries current or gets hot — about 700 MPa yield but 45–60 % IACS and a higher softening temperature. Both come as mill-hardened strip so the stamping needs no furnace.
Is beryllium copper safe to machine?
Solid parts are safe to handle; the hazard is respirable dust and fume. Turning and milling with coolant is routine, but grinding, polishing, EDM and any welding need extraction and housekeeping to the beryllium exposure limits. If the customer forbids beryllium entirely, C70250 (Cu-Ni-Si) and C72900 (Cu-Ni-Sn) reach 550–900 MPa yield without it.