Nickel Silver (CuNi18Zn20) Keys vs Standard Brass Key Blanks: Tensile Resistance
Engineering Overview: Technical evaluation of Nickel Silver (CuNi18Zn20) and Extruded Brass key blanks, analyzing torsional shear, key blade wear, and duplication tolerances.
Technical & Engineering Specifications
| Hardness | 180 HV (Nickel Silver) vs 110 HV (Brass) |
|---|---|
| Key Alloys | CuNi18Zn20 Nickel Silver vs CuZn37 Extruded Brass |
| Application | Master Key Systems & Commercial High-Security Keys |
| Tensile Strength | 700 MPa (Nickel Silver) vs 400 MPa (Brass) |
Key Blade Metallurgy & Torsional Load
Key blanks must withstand cyclic rotational torque without twisting or fracturing inside the keyway slot.
Alloy Comparison
- Standard Brass Key Blanks (CuZn37 / H62): Tensile strength ~400 MPa. Cost-effective for residential applications, but thin key blades can bend under binding mortise bolt loads.
- Nickel Silver Key Blanks (CuNi18Zn20 / German Silver):
- Tensile Strength: 650 to 750 MPa.
- Vickers Hardness: 160 to 200 HV.
- Abrasive Wear: Resists bitting notch rounding over 100,000 insertions, preserving precise master key shear line tolerances.
Frequently Asked Engineering & Selection Questions
Q1: Why do commercial master key systems require nickel-silver keys?
Nickel-silver provides high tensile strength (700 MPa) and extreme wear resistance, preventing cut bitting erosion that causes master key failures.