P20 and 1.2738 are both widely used pre-hardened plastic mould steels. On a quotation sheet they may appear to serve similar applications, but their real advantages become clearer as mould size, complexity and toughness requirements increase.

For buyers, the question is therefore not simply which steel is “better.”

The correct question is:

Which material provides the best balance for the specific mould?

P20 vs 1.2738 at a Glance

What Is P20 Mould Steel?

P20 is a general-purpose plastic mould steel valued for its balanced properties.

Its pre-hardened condition means mould manufacturers can machine it directly without performing another full hardening cycle.

This reduces tooling time and helps avoid distortion associated with secondary heat treatment.

P20 is commonly used for:

• Appliance housings
• Automotive plastic parts
• General injection moulds
• Storage containers
• Industrial plastic products
• Mould bases

What Is 1.2738 Mould Steel?

1.2738 is also supplied in a pre-hardened condition but is particularly associated with larger and more demanding plastic moulds.

Its combination of toughness, dimensional stability and polishing performance makes it suitable for large automotive and appliance tooling.

Typical applications include:

• Automotive bumpers
• Dashboards
• Door panels
• Large grilles
• Refrigerator housings
• Washing machine components
• Large industrial moulds

When Should You Choose P20?

P20 is often the more economical choice when:

• The mould is relatively straightforward
• Extremely high polishing is unnecessary
• Corrosion is not a major concern
• Production volume is moderate
• Machining efficiency is important
• The mould section is not unusually large

For many general injection moulds, upgrading to a more expensive material may provide little practical benefit.

When Does 1.2738 Make More Sense?

1.2738 becomes increasingly attractive when:

• The mould block is large
• Toughness is more important
• Dimensional stability is critical
• High surface finish is required
• The mould has deep cavities
• Complex slides or inserts create local stresses
• Downtime would be particularly expensive

This is why 1.2738 is frequently associated with automotive mould manufacturing.

Does 1.2738 Always Last Longer?

Not necessarily.

Mould life depends on much more than steel designation.

Important factors include:

• Plastic resin
• Glass-fibre content
• Injection pressure
• Tool design
• Surface treatment
• Cooling
• Machining quality
• Maintenance
• Production volume

A correctly designed P20 mould can outperform a poorly designed or poorly processed 1.2738 mould.

Buying Recommendation

Choose P20 when cost-effectiveness and machinability dominate.

Choose 1.2738 when the mould becomes larger, more complex or more sensitive to toughness and dimensional stability.

For an RFQ, send the mould dimensions, plastic material, expected production quantity and surface requirements rather than only requesting “P20 equivalent steel.”

Huangshi Xiri can then help match the supply condition and steel specification to the actual application.

FAQ

Is 1.2738 the same as P20?
No. They belong to a similar application family but should not automatically be treated as identical materials.

Which is better for automotive moulds?
For large bumpers, dashboards and other large automotive moulds, 1.2738 is frequently considered because of its suitability for large mould sections.

Which is cheaper?
P20 is generally positioned as the more cost-effective general-purpose option, although actual material cost depends on specification and supply condition.