Material grade C63000 is a high-performance copper-nickel-silicon alloy, commonly known by the trade name "HS-25" (High Strength 25) or "Copper-Nickel-Silicon 25." It falls under the category of "precipitation-hardening copper alloys"-meaning its strength and hardness can be significantly enhanced through a heat treatment process (solution annealing followed by aging).
C63000 is valued for its unique combination of high strength, excellent electrical conductivity, and good corrosion resistance-a rare balance that makes it ideal for applications requiring both mechanical durability and efficient electrical performance. Unlike standard brasses or pure copper (which trade strength for conductivity), C63000 retains ~45–55% of pure copper's electrical conductivity while offering tensile strength comparable to some low-carbon steels.
Common uses include electrical connectors (for automotive, aerospace, or industrial wiring), springs (e.g., electrical contact springs), fasteners in corrosive environments, and components for high-frequency electronics-where its strength prevents deformation and its conductivity ensures reliable signal/energy transfer.
The composition of C63000 is strictly defined by standards such as ASTM B196 (for copper alloy rod, bar, and wire) and ASTM B591 (for copper alloy forgings), with key elements optimized to achieve its strength and conductivity balance. The typical nominal composition (by weight) is:
This composition is critical: the nickel-silicon ratio ensures effective precipitation hardening, while strict impurity limits preserve the alloy's electrical and mechanical performance.
The hardness of C63000 varies significantly based on its heat treatment state-a defining feature of precipitation-hardening alloys. The two primary states (annealed and aged) produce drastically different hardness levels, tailored to specific application needs:
In the fully annealed state (heated to ~800–850°C, held, then cooled slowly), C63000 is softened to maximize ductility (for forming or machining). Its hardness in this state is:
Brinell Hardness (HB): ~60–80 HB
Rockwell Hardness (HRB): ~60–75 HRB
Vickers Hardness (HV): ~65–85 HV
This state is used for manufacturing processes like bending, stamping, or machining complex shapes, where flexibility is more important than maximum strength.
After solution annealing (to dissolve nickel and silicon uniformly) and aging (heated to ~450–500°C for several hours), hard nickel-silicon precipitates form throughout the alloy, drastically increasing hardness and strength. The typical hardness in the fully aged (T6) state is:
Brinell Hardness (HB): ~200–240 HB
Rockwell Hardness (HRC): ~20–28 HRC
Vickers Hardness (HV): ~210–250 HV
This is the most common state for end-use applications (e.g., electrical connectors, springs), where the alloy's high hardness ensures resistance to wear, deformation, and fatigue under repeated stress.
Note: Intermediate aging treatments can produce hardness values between the annealed and fully aged states, allowing manufacturers to balance strength and ductility for specialized needs.
