P20 (1.2311 / 1.2738) is a pre-hardened (28–34 HRC) chromium-molybdenum mold steel designed for uniform hardness across large cross-sections and exceptional mirror polishability for injection molds.
Engineering Specifications & Parameters
Density
7.85 g/cm³
Tensile Strength
980 - 1100 MPa
Supplied Hardness
28 - 34 Rockwell C (HRC)
Machinability Rating
65% (Pre-hardened)
Polishability Rating
SPI A-2 Mirror Grade
Thermal Conductivity
29 W/m·K
Pre-Hardened Advantages
Because P20 is supplied pre-hardened to 30 HRC, it requires no post-machining heat treatment, eliminating volumetric distortion and post-quench dimensional movement.
Cutting Feeds & High Metal Removal
Roughing: Cutting speed 100 – 160 m/min with high-feed face mills (HFM) and TiAlN/AlCrN inserts.
Finishing: Cutting speed 140 – 220 m/min with ball nose mills for 3D contoured mold cavities.
Polishability: P20 achieves SPI A-2 to A-1 optical mirror finishes with sequential diamond lapping compound.
Frequently Asked Questions
Why is P20 preferred over annealed tool steels for large mold cavities?
It eliminates post-machining heat treat distortion and decarburization risks for large injection molds.
How to achieve an SPI A-1 mirror finish on machined P20 mold cores?
Maintain consistent scallop height with ball end mills, followed by 600-1200 grit stone polishing and 3-micron diamond paste lapping.
