What is p20 steel hardness

P20 steel exhibits a range of hardness values depending on its processing, heat treatment, and intended application.

So, what is P20 tool steel? P20 steel is a versatile medium-alloy tool steel primarily utilized in the mold-making industry, especially for plastic injection molds and die-casting dies for low-melting-point alloys.
Its defining characteristic is that it is most commonly supplied in a pre-hardened condition. This allows mold cavities to be directly machined without the need for subsequent high-temperature heat treatment, which significantly minimizes distortion and size changes in complex mold components.

Now that we have briefly introduced P20, let’s return to the topic of P20 steel hardness. Here’s a breakdown of P20 steel hardness in various conditions.

1. As-Supplied (Pre-hardened) Condition

P20 steel is typically supplied in a pre-hardened condition, allowing it to be machined directly into mold cavities without the need for subsequent high-temperature heat treatment, which helps minimize deformation and dimensional changes. The hardness range of P20 steel in the pre-hardened state is typically 28 to 40 HRC. For applications requiring higher hardness, P20 can be pre-hardened to a hardness of 40 HRC or higher.

2. Carburized and Hardened Condition

P20 steel can be carburized and then P20 steel hardened to increase surface hardness and wear resistance. After carburizing and hardening, the surface hardness of P20 steel can reach 65 HRC. The core hardness after carburizing is typically about 45 HRC.

The carburizing temperature impacts the resulting surface hardness. For example, specimens carburized at 845 °C (1550 °F) achieved a surface hardness of 65.6 HRC, while those carburized at 980 °C (1800 °F) resulted in 58.6 HRC.
Tempering a carburized P20 steel will cause a decrease in its surface hardness, and its resistance to softening during tempering is considered relatively low, similar to plain carbon steel.

3. Heat-Treated (Quenched and Tempered) Condition

P20 can be oil-quenched and then tempered to achieve specific hardness levels for various applications.

Hardness of P20 steel after quenching and tempering¹

Tempering Temperature	Rockwell C Hardness
As quenched	51
400°F / 205°C	49
600°F / 315°C	47
800°F / 425°C	44
1000°F / 540°C	39
1100°F / 595°C	33
1200°F / 650°C	26
1250°F / 675°C	21

• Preheat Temperature: 1200°F / 650°C （If used on larger mass parts.）
• Hardening Temperature: 1525°F / 830°C
• Quenching Method: Oil Quench and Carburize
• CHEMISTRY: Carbon 0.30%, Manganese 0.75%, Silicon 0.50%, Chromium 1.65% , Molybdenum 0.40%

Summary

P20 steel is typically encountered as a pre-hardened material in the 28-40 HRC range for ease of machining, but it can be case-hardened to surface hardnesses up to 65 HRC for enhanced wear resistance, or heat-treated to various other hardness levels through quenching and tempering, depending on specific application requirements.

1. Bryson, W. E. (2007). Heat Treatment, Selection, and Application of Tool Steels (p. 195). Hanser Publications. ↩︎