2738 Plastic Mould Steel
DIN 1.2738 (40CrMnNiMo8-6-4) · AISI P20+Ni · GB 3Cr2MnNiMo
DIN 1.2738 (commonly referred to as "2738") is the nickel-modified premium version of the P20/2311 family. The addition of approximately 1% nickel serves a dual purpose: it improves hardenability to ensure consistent hardness through thicker cross-sections (up to 400 mm and beyond), and it refines the microstructure, resulting in better toughness and superior polishability compared to standard 2311.
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Material Properties
2738 achieves uniform hardness of 290–340 HB throughout cross-sections that would show core hardness drop in plain P20. The nickel addition contributes to a finer, more homogeneous microstructure which directly benefits polishability and reduces the risk of "orange peel" surface defects during polishing. Machinability is slightly lower than 2311 due to the higher alloy content and hardness, but remains good for CNC milling with carbide tooling. Weldability requires preheating to 200–300°C. The grade offers better resistance to plastic melt erosion than 2311.
Like 2311, the grade is supplied in the pre-hardened condition — typically 290–340 HB (approximately 30–36 HRC) — eliminating post-machining heat treatment. The improved hardenability makes 2738 the preferred choice for large mould blocks where standard 2311 may show a significant hardness drop at the core relative to the surface.
The enhanced polishability of 2738 makes it suitable for plastic moulds where aesthetics matter — for example, consumer product packaging, appliance housings, and medium-gloss automotive interior components. For the highest optical quality (VDI ≤ 0), Tiangong's exclusive grade TGP80 is recommended.
Chemical Composition (%)
| Element | Content (%) |
|---|---|
| C | 0.35 – 0.45 |
| Si | 0.20 – 0.40 |
| Mn | 1.30 – 1.60 |
| Cr | 1.80 – 2.10 |
| Mo | 0.15 – 0.25 |
| Ni | 0.85 – 1.15 |
| P | ≤ 0.030 |
| S | ≤ 0.030 |
Mechanical Properties
| Property | Value |
|---|---|
| Hardness (Supply Condition) | 290 – 340 HB (30 – 36 HRC) |
| Tensile Strength | 1 000 – 1 150 MPa |
| Yield Strength (0.2%) | 850 – 1 000 MPa |
| Impact Toughness (KU2) | ≥ 68 J |
| Density | 7.85 g/cm³ |
Typical Applications
Frequently Asked Questions
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Plastic Mould Steel
Related Grades
Other grades in the same product family that may suit your application.
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2311
Plastic Mould Steel
Pre-hardened plastic mould steel (28–34 HRC) suitable for medium-to-large injection mould bases and inserts. No heat treatment required after machining.
View Details →product-tgp80-plastic-mould.jpg
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TGP80
★Plastic Mould Steel
Tiangong's exclusive premium plastic mould steel, pre-hardened to 38–42 HRC with exceptional mirror polishability for optical and high-gloss injection mould applications.
View Details →Need 2738 in Indonesia?
Get a competitive quote within 1 business day. Material in stock at our Cikarang warehouse — available for same-day cutting and in-house CNC machining.