H13 Tool Steel Machinability

Understanding H13 tool steel machinability is key to efficient production and high-quality parts. Aobo Steel offers this guide to help you optimize your H13 machining processes.

H13 Tool Steel: Core Properties & Applications

H13 is a 5% chromium, air-hardening hot work tool steel known for:

• Good red hardness
• High abrasion resistance
• Excellent heat checking resistance

Common H13 applications include:

• Die-casting dies
• Plastic-injection molds
• Forging tools
• Extrusion tooling

H13 is typically used at 45–50 HRC for die-casting or 40–44 HRC for shock-resistant applications.

Factors Influencing H13 Tool Steel Machinability

Machinability refers to the ease of cutting a material. For H13, it’s influenced by:

• Workpiece Condition: Annealed vs. hardened state.
• Cutting Tool: Material and geometry.
• Machining Operation: Turning, milling, etc.
• Operating Conditions: Speed, feed, depth of cut.
• Cutting Fluid: Type and application.
• Machine Tool Rigidity.

Good machinability means lower tool wear, reduced cutting forces, manageable chips, and better surface finish.

Optimizing H13 Tool Steel Machinability

Optimal H13 tool steel machinability depends on its annealed state and microstructure.

The Importance of Annealing

For best results, machine H13 in its annealed condition. Annealing softens the steel, improving tool life.

H13 Annealing Parameters:

Annealing Step	Temperature	Duration/Rate	Target Annealed Hardness
Heating	~1600°F (871°C)	–	–
Soaking	At ~1600°F (871°C)	One hour per inch of material thickness	–
Slow Cooling	Down to 900°F (482°C)	At a rate of 25°F (14°C) per hour	–
Final Cooling	From 900°F (482°C) to room temperature	Air cool	Approx. 220 HB maximum

This process creates a microstructure favorable for machining. For more information, please click H13 steel heat treatment.

H13 Machinability Ratings

Annealed H13 tool steel typically has a machinability rating of 70-75% compared to:

• 70% vs. 1% carbon steel (rated 100%).
• 75% vs. annealed W1 tool steel (rated 100%).

Note: A 100% tool steel rating is about 30% of a constructional steel like AISI B1112.

Microstructure’s Role in Machining H13

H13 (approx. 0.4% carbon) machines best with a spheroidized microstructure: small, rounded carbides in a softer ferrite matrix. Vanadium in H13 forms hard carbides (V-rich MC, Mo-rich M6C, Cr-rich M23C6) during tempering. These aid wear resistance but can increase tool wear if not machined in the properly annealed state.

Practical Machining Guidance for H13

Machining Annealed H13

In its annealed state (180-230 HB), H13 offers good machinability with HSS or carbide tools. Ensure:

• Full annealing to correct hardness.
• Appropriate speeds, feeds, and depths of cut.
• Suitable cutting fluids.

Machining Hardened H13

Machining hardened H13 (40-52 HRC) is difficult and requires:

• Specialized Tooling: PCBN tools are often necessary.
• Reduced Machining Rates: Expect slower material removal.
• Surface Treatments: Nitrided surfaces (over 1000 HV / 70 HRC) are extremely hard to machine, often requiring grinding or EDM.

Benefits of Premium H13 Grades

ESR-refined H13 offers improved cleanliness and homogeneity, benefiting polishability and potentially improving H13 tool steel machinability.

Your H13 Partner: Aobo Steel

Aobo Steel has over 20 years of experience in forging and supplying tool steels like H13. We understand the importance of H13 tool steel machinability for your operations. Our team can help you select the right H13 grade and provide machining insights.

Conclusion: Efficient H13 Machining

H13 tool steel provides a good balance of properties, and its machinability is favorable when correctly handled, primarily by machining in the annealed condition (~220 HB). Understanding the factors influencing H13 tool steel machinability optimizes processes and ensures component performance.

Contact Aobo Steel for your H13 tool steel needs.