P20+Ni steel is a mirror-finish plastic mold steel developed by enhancing the American P20 steel with the addition of Ni alloy. This steel features high hardenability, excellent polishability, electrical discharge machining (EDM) performance, and texturing properties. How those properties play out at the bench is covered in the plastic mold steel polishing and texturing guide. Pre-hardened with high purity and uniform structure, it is ideal for high-demand plastic molds, particularly those requiring electrical discharge machining.
1. The applications of P20+Ni steel
Plastic Injection Moldsmirror-finish plastic mold
Ideal for manufacturing complex and high-precision plastic molds.
Suitable for large-scale mirror-finish plastic mold production.
2. P20+Ni steel chemical composition
Carbon (C)
Silicon (Si)
Manganese (Mn)
Phosphorus (P)
Sulfur (S)
Chromium (Cr)
Molybdenum (Mo)
Nickel (Ni)
0.35 – 0.45
0.20 – 0.40
0.60 – 1.60
≤ 0.030
≤ 0.030
1.80 – 2.10
0.15 – 0.25
0.90 – 1.20
3. P20+Ni steel physical properties
Property
Value
Unit
Density
7.7 – 7.85
g/cm³
Hardness (Pre-hardened)
280-320
HB
~28-32
HRC
Tensile Strength
850 – 1300
MPa
Yield Strength
770 – 1000
MPa
Elongation
13 – 16
%
Impact Toughness
20 – 42
J/cm²
Modulus of Elasticity
205 – 212 x 10³
MPa
Thermal Conductivity
* At 20°C
29 – 35
W/(m·K)
* At 350°C
~34
W/(m·K)
* At 700°C
~33
W/(m·K)
Thermal Expansion Coeff.
* 20-100°C
11.2 – 12.0 x 10⁻⁶
/K
* 20-200°C
12.8 x 10⁻⁶
/K
* 20-300°C
13.5 x 10⁻⁶
/K
Critical Temperatures
°C
* Ac1
720
°C
* Ac3
800
°C
* Ms
290
°C
Soft Annealing Temp.
710-740
°C
Stress Relieving Temp.
560-600
°C
Hardening Temperature
840-880
°C
Tempering Temperature
100-700
°C
4. P20+Ni equivalents DIN 1.2738
1.2738 steel is a German super-pre-hardened plastic mold steel, supplied in a pre-hardened condition that eliminates the need for additional heat treatment and allows direct machining into molds. It offers excellent machinability, facilitates cutting and polishing, and undergoes stress-relief annealing and surface nitriding treatment with minimal dimensional and hardness changes. Particularly suitable for plastic mold frames with a thickness greater than 400mm.
