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What are the common types of mold steel?

2025-11-10 16:12
Mold steel is the core material for manufacturing molds. According to its application scenarios and performance requirements, it can be mainly divided into three categories: cold work mold steel, hot work mold steel, and plastic mold steel. The following are common models and characteristics of each category:

Cold work die steel

Characteristics: Cold work die steel works at room temperature and requires extremely high hardness, wear resistance, and sufficient toughness to withstand high stress and friction during stamping, shearing, and other processes.

Common Mold steel grades and characteristics:

Cr12MoV: High carbon and high chromium steel commonly used in China, with good wear resistance but relatively low toughness, suitable for punching dies with simple shapes and low loads.

D2 (AISI D2): Air cooled hardened steel with high carbon content and excellent wear resistance, but poor toughness, commonly used in cold heading dies, drawing dies, etc.
DC53: Improve toughness based on SKD11 while maintaining high hardness, suitable for precision stamping and complex molds.
SKD11: Balance of wear resistance and toughness, widely used in punching and forming molds.

Application scenarios: Stamping die, shearing die, cooling die, deep drawing die, etc.

Hot work mold steel

Characteristics: Hot work die steel needs to work at high temperatures (such as die-casting, hot forging), requiring red hardness (maintaining hardness at high temperatures), thermal fatigue resistance, good thermal conductivity, and toughness.

Common Mold steel grades and characteristics:

H13 (4Cr5MoSiV1): The most commonly used hot work steel in the world, with excellent comprehensive performance, suitable for aluminum alloy and magnesium alloy die-casting molds, and a service life of tens of thousands of molds.
SKD61: Die cast steel, with higher purity and better thermal fatigue performance than H13, suitable for high-precision die casting.
1.2344 (X40CrMoV5-1): German standard steel with strong heat shock resistance, commonly used in copper alloy hot forging dies.

Application scenarios: High temperature components of die-casting molds, hot forging molds, hot extrusion molds, and plastic injection molds.

Plastic mold steel

Characteristics: Plastic mold steel needs to meet high polishing, corrosion resistance, dimensional stability, and ease of processing, especially with high requirements for surface smoothness.

Common brand names and characteristics:
P20 (3Cr2Mo): Pre hardened steel (factory hardness 28-32HRC), can be directly processed without heat treatment, low cost, suitable for injection molding of household appliances and daily necessities.
NAK80: Mirror steel, can achieve mirror effect after polishing, with a hardness of 40-45HRC, suitable for transparent plastic (such as PC, acrylic) products.
S136 (4Cr13): Martensitic stainless steel, strong corrosion resistance, hardness 50-52HRC, used for chlorine containing plastics (such as PVC) or high gloss molds.

Application scenarios: injection molds, blow molding molds, extrusion molds, etc.

Key factors for selection

Working conditions:
Cold work molds prioritize hardness and wear resistance (such as D2, DC53).
Hot work molds should pay attention to red hardness and thermal fatigue resistance (such as H13, SKD61).
Plastic molds emphasize polishing and corrosion resistance (such as P20, S136).

Cost and lifespan:
Pre hardened steel (such as P20) can shorten the processing cycle and is suitable for small and medium-sized production.
High alloy steel (such as H13, S136) has high cost but long service life, making it suitable for large-scale production.

Processing performance:
High hardness steel (such as D2, S136) requires wire cutting or electrical discharge machining, which results in higher costs.

The selection of mold steel requires a comprehensive consideration of material properties, process requirements, and economy. For example:

The stamping die can be selected from DC53 or SKD11, balancing toughness and wear resistance.
Die casting molds prioritize H13 or SKD61 to ensure high temperature stability.
Transparent plastic products require NAK80 or S136 to ensure surface smoothness.

I hope this detailed classification and selection guide can help you better understand the application of mold steel! If you have any questions about specific scenarios, please feel free to further explore.
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