12738 Steel Enhances Mold Performance in Manufacturing

Imagine this scenario: your plastic products consistently develop defects, mold lifespans fall far short of expectations, and production costs remain stubbornly high. The root cause might lie in your choice of mold steel. This article provides an in-depth analysis of 1.2738 (P20+Ni) mold steel, helping manufacturers improve product quality, extend tool longevity, and reduce production costs.

1.2738 mold steel, also known as P20+Ni or AISI P20+Ni, represents a premium-grade material widely used in plastic mold fabrication. Its exceptional balance of properties has established it as an industry standard, particularly for large plastic mold components. What makes this steel stand out from alternatives?

The chemical composition of 1.2738 mold steel forms the foundation of its superior performance. Nickel (Ni), chromium (Cr), and molybdenum (Mo) serve as primary alloying elements, working synergistically to deliver high hardness, strength, and wear resistance. The precise chemical ranges include:

• Carbon (C): 0.35-0.45%
• Manganese (Mn): 1.30-1.60%
• Silicon (Si): 0.20-0.40%
• Chromium (Cr): 1.80-2.10%
• Molybdenum (Mo): 0.15-0.25%
• Nickel (Ni): 0.90-1.20%
• Phosphorus (P): ≤0.030%
• Sulfur (S): ≤0.030%

The material's outstanding physical and mechanical characteristics enable it to handle demanding mold applications. Key specifications include:

• Elastic modulus: 205 x 10³ N/mm²
• Density: 7.80 g/cm³
• Thermal conductivity (100°C): 33.5 W/m·K
• Specific heat capacity: 0.46 J/g·K
• Tensile strength: ≈1080 N/mm²
• Hardness: Typically supplied in pre-hardened condition (280-320 BHN or 32-36 HRC)

Supplied in pre-hardened condition, 1.2738 steel maintains excellent machining characteristics for milling, drilling, and tapping operations, reducing tooling costs.

The material achieves high-gloss surface finishes critical for appearance-sensitive applications.

1.2738 steel readily accepts various surface textures for enhanced product aesthetics.

While challenging, welding remains feasible with proper preheating and post-weld heat treatment to minimize stress and cracking.

Nickel content significantly boosts hardness and wear resistance, extending service life.

Common international designations include:

• DIN: 2738, 40CrMnNiMo8-6-4
• AISI: P20+Ni

While typically used in pre-hardened condition, optional treatments include:

• Forging: 1050-850°C
• Quenching: 840-870°C
• Soft annealing: 710-740°C

1.2738 mold steel serves diverse plastic processing applications, particularly:

• Injection molds for automotive components, appliance housings, and electronics
• Low-melting-point metal die casting
• Large-scale molds (bumpers, appliance enclosures)
• Hydroforming equipment
• Automotive and consumer goods tooling

Critical purchasing considerations include:

• Partnering with certified suppliers
• Verifying material certifications
• Selecting appropriate hardness grades
• Inspecting for surface defects

Industry alternatives encompass:

• Carbon steels: C45, EN8-9, C35-C60 series
• Alloy steels: EN19, EN24, 42CrMo4
• Tool steels: D2/D3, H-11/13, M-series
• Specialty grades: SKD-11, P20 variants, SAE series

1.2738 (P20+Ni) mold steel delivers an optimal combination of properties for plastic mold fabrication. Understanding its composition, characteristics, processing requirements, and applications enables manufacturers to maximize product quality while controlling production costs through extended tool life and reduced downtime.