Grade 1.2738, also known as P20+Ni, is a high-quality, pre-hardened mould steel used extensively in the plastic mould industry. It is an upgraded version of the standard P20 steel (1.2311), with the addition of nickel, which significantly improves hardness uniformity, toughness, and polishability. Because 1.2738 is delivered in a pre-hardened condition (typically 32–36 HRC), it does not require additional heat treatment, reducing machining time and eliminating the risk of distortion.

Key Properties of 1.2738 (P20+Ni)

1. Excellent Hardness Uniformity

Thanks to its nickel content, 1.2738 maintains consistent hardness from the surface to the core. This is crucial for large plastic moulds that require dimensional stability and long service life.

2. High Toughness & Strength

The alloy composition provides superior toughness compared to standard P20. This minimizes the chances of cracking during machining or mould operation and allows the steel to withstand higher injection pressures.

3. Good Machinability

Even in its pre-hardened state, 1.2738 can be easily machined using standard tooling. Milling, drilling, turning, and grinding are efficient, reducing production time and overall costs.

4. Excellent Polishability & Texturing

1.2738 has a fine microstructure, allowing it to achieve a high-quality mirror polish. It also accepts chemical and laser texturing very well, making it suitable for automotive, cosmetic, and consumer product moulds that require premium surface finishing.

5. Suitable for Nitriding

1.2738 can be nitrided to achieve surface hardness 55–60 HRC, which improves wear resistance without affecting its tough core. This significantly increases mould lifespan.

6. Good Weldability

Repairs and engineering modifications are easier due to the steel’s good weldability. The nickel content ensures stable hardness after welding when proper procedures are followed.

Common Applications

1. Large plastic injection moulds

2. Blow moulds

3. Automotive interior & exterior moulds

4. Die-casting moulds for low-melting alloys

5. Mould bases and plate materials

6. Moulds requiring high-quality polishing and texturing

Summary

1.2738 (P20+Ni) is an enhanced mould steel offering superior hardness uniformity, toughness, and polishability compared to ordinary P20 steels. Its pre-hardened condition, easy machinability, and suitability for large mould structures make it one of the most widely used materials in the plastic mould-making industry.