P20 vs H13: Which Mold Steel Should You Really Buy?

When it comes to mold-making, picking the right steel is kind of like choosing the perfect tool for your toolbox. Get it right, and your job becomes easier, faster, and more efficient. Get it wrong, and well… you might be setting yourself up for costly repairs or poor-quality results.

 

When it comes to mold-making, picking the right steel is kind of like choosing the perfect tool for your toolbox. Get it right, and your job becomes easier, faster, and more efficient. Get it wrong, and well… you might be setting yourself up for costly repairs or poor-quality results.

So, let’s talk about P20 vs H13 — two of the most popular mold steels out there. Which one should you really buy? Whether you're a hobbyist, a manufacturer, or just someone curious about what goes into making molds, this article will break it down in simple, friendly language.

Let’s dive into this steel showdown!

What is Mold Steel and Why It Matters

Think of mold steel as the foundation of a house. If the foundation is weak, everything built on top is compromised. check valvesare used to create molds for shaping plastic, rubber, and even metal. So, the performance, longevity, and finish of the final product often depend on the type of steel you choose.

Getting to Know P20 Steel

P20 is a popular pre-hardened tool steel often used in plastic injection molding. It’s known for:

Good machinability

Decent toughness

Fair polishability

Lower cost

In simple terms, P20 is like that reliable family car — not flashy, but dependable, affordable, and gets the job done.

Applications of P20 Steel – Where It Shines

Mold Making:
P20 steel is best known for its role in mold making, especially for injection molds. Thanks to its excellent machinability and ability to take on a high polish, it’s perfect for crafting molds that need fine details and smooth surface finishes — exactly what's needed for plastic components or die-cast parts made from aluminum, zinc, or magnesium.

Tool Holders:
Because it’s tough and resistant to cracking — even under heat and long-term stress — P20 steel is also a solid choice for tool holders. These components need to be reliable and long-lasting, and P20 delivers.

Automotive Industry:
In the automotive world, P20 is a go-to for making molds used to produce parts like dashboards, bumpers, interior panels, and other complex shapes. It handles the demands of high-volume production while providing the smooth finish modern car parts require.

Product Development & Prototyping:
P20 is also widely used in prototyping and product development. It lets teams move quickly from design to testing without the need for harder (and more expensive) tool steels unless needed for final production. That speed and flexibility are key for innovation.

Carrier Frames & Holders:
Beyond traditional mold-making, P20 shows up in structural applications too — like carrier frames and holders. Its solid mechanical properties mean it performs well with minimal wear and tear, offering durability and strength where it counts.

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Mechanical & Thermal Properties of P20 Steel – Why It Performs So Well

Mechanical Properties:
P20 falls into the category of pre-hardened plastic mold steels, meaning it’s ready to go without needing further hardening. It typically offers:

• Tensile strength: ~850–1,000 MPa

• Yield strength: ~750–930 MPa

• Hardness: ~300–320 HB (Brinell)

That means it can handle serious stress during use without deforming, which is critical in mold-making.

P20 is also quite ductile, with elongation at break ranging from 15–25%, allowing it to be shaped and worked without cracking. On top of that, it has solid impact strength, so it can take on frequent or sudden loads — perfect for molds that go through lots of cycles.

Thermal Properties:
P20 steel manages heat pretty well, which is a huge plus in molding applications. Here’s what you should know:

• Thermal expansion coefficient: ~11.7 µm/m°C (from 20–100°C) — useful for predicting dimensional changes as temperatures shift.

• Thermal conductivity: Good — helps dissipate heat efficiently during and after molding, aiding faster cooling times and improving mold longevity.

Tempering Flexibility:
P20 can be tempered at different temperatures (typically between 550°C to 650°C) to fine-tune the balance between toughness and hardness. That makes it super adaptable depending on what the job calls for.

Meet the Mighty H13 Steel

H13 steel is a super versatile chromium-molybdenum alloy that sees a lot of action in manufacturing and heavy-duty industries. Why? Because it strikes a great balance — it's tough, holds up well under heat, and keeps its hardness even when things get hot. It’s especially good in situations where tools are constantly being heated and cooled, like in die casting or forging.

One thing that makes H13 stand out is its ability to handle sudden temperature drops without cracking or losing its edge — literally. That’s thanks to its solid composition and the way it reacts to heat treatment. Unlike some steels that need oil or water quenching, H13 can be air-hardened, which makes the process easier and less risky. Less chance of cracking means longer tool life and fewer headaches.

On top of that, H13 has excellent resistance to thermal fatigue — so even when it’s exposed to high heat again and again, it keeps performing. That’s a huge plus in fast-paced, high-heat applications where reliability matters.

Because of all these traits — toughness, heat resistance, and flexibility in treatment — H13 steel is a go-to choice in industries that demand durability and precision under stress.

What’s H13 Steel Made Of?

H13 steel is a chromium-molybdenum hot work tool steel known for its excellent strength and heat resistance. Its composition includes:

Iron (Fe): The primary component, forming the base of H13 steel.

Chromium (Cr) (~5%): Enhances hardness, wear resistance, and corrosion resistance.

Molybdenum (Mo) & Vanadium (V) (~1% or less each): Improve toughness, grain structure, and high-temperature strength.

Silicon (Si) (<1%): Increases strength and acts as a deoxidizer for cleaner steel.

Carbon (C) (~0.4%): Essential for hardness after heat treatment, while maintaining manageable brittleness.

Manganese (Mn) & Sulfur (S): Present in small amounts to improve machinability.
 

Applications of H13 Steel

1. Tooling Industry
Widely used for hot work tools such as forging dies, extrusion dies, and die-casting tools due to its ability to endure repeated thermal cycles without degradation.

2. Die Casting for Non-Ferrous Metals
Ideal for casting aluminum and other non-ferrous metals, thanks to its excellent resistance to thermal shock and wear.

3. Aerospace Sector
Used in critical components like turbine blades and landing gear, where materials must withstand extreme heat and mechanical stress.

4. Plastic Molding Industry
Preferred for molds that require high polish and abrasion resistance, particularly for abrasive plastics.

5. Other Applications
Includes hot work punches, drill bits, and high-speed stamping tools—anywhere that tools are exposed to high heat and friction.

Mechanical and Thermal Properties of H13 Steel

Hardness: Around 52–54 HRC when tempered, allowing for sharp edges and abrasion resistance.

Toughness: High impact resistance reduces the risk of chipping or cracking under heavy loads.

Heat Resistance: Maintains structural integrity up to ~600°C (1112°F), suitable for hot-working environments.

Thermal Conductivity: Promotes efficient heat dissipation during high-temperature operations.

Thermal Shock Resistance: Excellent resistance to cracking from rapid temperature changes.

Key Differences Between H13 and P20 Steel

1. Heat Resistance and Hardness

• H13 Steel:
  Designed for hot work applications, H13 steel retains its hardness at high temperatures due to its high alloy content (chromium, molybdenum, and vanadium). It is ideal for die-casting and forging operations that involve intense heat.

• P20 Steel:
  Supplied in a pre-hardened state, P20 is suitable for applications that don’t reach extreme temperatures. Its lower hardness makes it better for moderate-duty uses like plastic injection molds.

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2. Machinability

• H13 Steel:
  Due to its higher hardness and alloy content, H13 is more difficult to machine. It often requires high-speed steel or carbide cutting tools and careful process control.

• P20 Steel:
  Offers excellent machinability. Its lower carbon content allows it to be easily shaped using conventional machining techniques, reducing time and labor costs.

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3. Cost

• H13 Steel:
  Generally more expensive to purchase and machine, but offers longer tool life in high-temperature environments, which may offset the higher initial investment over time.

• P20 Steel:
  More economical upfront. Its ease of machining and no need for post-treatment (being pre-hardened) make it cost-effective for lower-stress applications.

 

Additional FAQs

Does P20 Steel Rust Easily?

Yes. P20 steel does not have strong corrosion resistance. It should be kept dry and regularly oiled, especially in humid environments, to prevent rust and extend its lifespan.

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Can H13 Steel Be Used for Cold Work Applications?

Not ideally. H13 is designed for high-temperature operations and lacks the ductility and wear resistance required for cold work. For cold working processes, steels like D2 or O1 are typically better choices.

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What Are the Best Applications for H13 and P20 Steel?

• H13 Steel:

  • Die casting tools

  • Hot forging dies

  • Extrusion dies

  • High-temperature tooling in the aerospace and automotive industries

• P20 Steel:

  • Plastic injection molds

  • Die holders

  • Molding bases

  • Prototyping and detailed molds requiring high polish