High-Speed Tool Steel｜High Hardness & Heat Resistance for Precision Cutting and Forming

In industries that rely on cutting tools, drills, end mills, and stamping dies, one of the most common challenges is the loss of cutting-edge sharpness and tool hardness during high-speed operation. When the cutting temperature exceeds 500°C, conventional steels begin to soften, resulting in dull edges, burning, or deformation dramatically reducing cutting performance and tool life. To overcome these issues, manufacturers turn to High-Speed Tool Steels (HSS) engineered to maintain exceptional hardness and toughness even under extreme heat. These steels are ideal for high-speed cutting, precision machining, and metal forming applications.

Key Industry Problems

During high-speed cutting operations, frictional heat causes tool temperatures to soar above 500°C. Standard tool steels such as SKS or SKD lose their carbide stability, leading to softening, chipping, or cracking of the cutting edge. This results in shorter tool life, lower accuracy, and frequent regrinding or replacement.

Root Cause

Conventional tool steels cannot form stable carbides at elevated temperatures. As a result, their microstructure degrades, hardness drops, and red hardness (hot hardness) is lost. In contrast, High Speed Tool Steels (HSS) are specially alloyed to retain their hardness and resist softening, thanks to their ability to form strong, heat-stable carbides — maintaining cutting efficiency even at 550–600°C.

Yamaichi’s Solution

Yamaichi Special Steel (Thailand) supplies premium-grade High Speed Tool Steel conforming to JIS G4403, including SKH51, SKH55, and Matrix Type grades. Produced through the advanced ESR (Electro Slag Remelting) refining process, these steels feature a fine, uniform microstructure, high purity, and excellent toughness. They can reach hardness levels of HRC 63–66 while maintaining their structure and cutting performance even above 550°C. Ideal for metal cutting tools, drills, end mills, industrial blades, punches, and progressive dies, Yamaichi’s high-speed tool steels deliver both durability and precision in demanding production environments.

Characteristics of YAMAICHI High-Speed Tool Steel

1. SKH51 — Industry Standard (Equivalent to M2 Grade)

• Molybdenum-based high-speed steel (standard industrial grade)
• Hardness: HRC 64–66, excellent red hardness
• Fine, evenly distributed carbide structure for superior wear resistance
• Balanced hardness, toughness, and dimensional stability
• Ideal for drills, end mills, cutting blades, and sheet metal dies

2. SKH55 — Premium High-Speed Steel (Equivalent to M35 Grade)

• Developed from SKH51 with ~5% Cobalt (Co) addition
• Enhanced resistance to softening and oxidation at high temperature
• Maintains hardness even above 600°C
• Suitable for high-speed cutting of stainless steels, alloy steels, and hard metals
• Longer tool life and improved heat resistance compared to SKH51

3. Matrix Type — High Toughness, Fine Structure Type

• Refined by High Purity ESR Process for uniform microstructure
• Combines high hardness (HRC 63–65) with excellent toughness
• Withstands high impact loads ideal for cold forming dies, progressive dies, and punches
• Prevents chipping and cracking, extending tool and die life

Key Advantages of Yamaichi High Speed Tool Steel

• Japan Quality Manufacturing — precise alloy and hardness control
• Fine Carbide Structure — reduces cracking and enhances toughness
• Excellent Red Hardness — maintains hardness at 550–600°C
• Coating Compatibility — suitable for TiN, TiCN, AlCrN coatings
• Cut-to-Length and Heat Treatment Services available via the Yamaichi Group

SKH51 / SKH55 / Matrix Type high-speed tool steels from Yamaichi Special Steel (Thailand) offer the perfect balance of hardness, heat resistance, and durability. Designed for high-speed cutting, stamping, and precision forming, these Japan-quality steels help manufacturers achieve longer tool life, consistent performance, and higher production efficiency.

※ For more information, please contact us below or download our brochure.

Glossary

• Red Hardness: The ability of steel to retain hardness under high temperatures
• ESR (Electro Slag Remelting): Refining process for cleaner, inclusion-free steel
• Stable Carbide: Carbides that resist dissolution at elevated temperatures
• TiN / TiCN / AlCrN: Common hard coatings for improving wear and heat resistance

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