Copper Alloy ERCuNi vs ERCuSi-A
Copper Alloy · grade comparison
Copper Alloy ERCuNi and ERCuSi-A are both copper alloy grades. ERCuNi is the stronger of the two: yield strength 220 MPa (31.9 ksi) against 195 MPa (28.3 ksi) for ERCuSi-A, about 13% more; tensile strength follows at 400 MPa (58 ksi) vs 350 MPa (50.8 ksi). In exchange, ERCuSi-A is the more ductile: elongation 38% versus 32% for ERCuNi, and ERCuNi is harder (90 HB vs 85 HB). ERCuSi-A is lighter (8.53 g/cm³ vs 8.94 g/cm³ for ERCuNi) and ERCuNi is stiffer (152 GPa vs 103 GPa). On the shop floor, ERCuSi-A welds better (excellent vs very good).
ERCuNiChoose it when strength drives the design, or when the part sees heat.
ERCuSi-AChoose it when the part is bent, formed or impact-loaded, or when weight is the constraint.
ERCuNi vs ERCuSi-A: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all copper alloy grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all copper alloy grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Shear Modulus
Bulk Modulus
Poisson's Ratio
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Shear Strength
Fatigue Strength (Endurance Limit)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell B
Hardness, Vickers
Same in both: Reduction in Area 45%
Physical
Density and transition temperatures.
Density
Melting Point (Solidus)
Liquidus Temperature
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Latent Heat of Fusion
Max Service Temperature (continuous)
Min Service Temperature
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Galvanic Potential (seawater, vs SCE)
Corrosion Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Castability
Brazeability / Solderability
Polishability
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Typical Recycled Content
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Modulus of Resilience
Thermal Diffusivity
Thermal Shock Resistance Index
Strength versus weight
Yield strength against density for every copper alloy grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Manufacturing and finishing
| Capability | ERCuNi | ERCuSi-A |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$$$ High | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Both take the same 4 finishes: Copper Plating, Electroless Nickel (EN), Gold Plating, Silver Plating.
ERCuNi vs ERCuSi-A — frequently asked
Is ERCuNi stronger than ERCuSi-A?
Yes. ERCuNi has a typical yield strength of 220 MPa (31.9 ksi) against 195 MPa (28.3 ksi) for ERCuSi-A — about 13% more. Tensile strength is 400 MPa (58 ksi) vs 350 MPa (50.8 ksi).
Which is cheaper, ERCuNi or ERCuSi-A?
Both sit in the same relative cost tier ($$$$, high); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which is easier to machine, ERCuNi or ERCuSi-A?
ERCuSi-A, by a small margin. Both rate poor for machinability — 33/100 against 28/100 for ERCuNi; for welding the order is ERCuSi-A first (excellent, 90/100) then ERCuNi (very good, 78/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in ERCuNi and ERCuSi-A side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.
Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.