Guide to High-Speed Steel (HSS): Why It’s Still a Top Choice for Cutting Tools

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The appearance of High-speed steel(HSS) has changed the world of machining. It was first developed by American engineer Frederick W. Taylor and metallurgist Maunsel White in 1898. It became commercially available around 1900. A century later, HSS is still an important material in industrial tooling.

High-Speed Steel (HSS) is a type of tool steel known for its ability to maintain hardness and withstand high temperatures, making it ideal for cutting tools and industrial machining.

This guide will explain HSS in detail. It covers its composition, key properties and wide industrial uses. It will help you understand why this material, which has been used for over 100 years, is still a leader in cutting tool manufacturing.

What is HSS?

High-speed steel (HSS) is a type of tool steel made for cutting, according to ASTM A600, a key international standard for tool steels. This definition comes from its special performance traits. Even at high temperatures, HSS keeps a sharp cutting edge.

HSS gets its special properties from a specific mix of alloying elements.

• Main components: Iron (the base metal) and carbon (which gives basic hardness).
• Key alloying elements: Tungsten, molybdenum, chromium and vanadium.
• Tungsten and molybdenum: Improve high-temperature resistance (also called red hardness).
• Chromium: Makes corrosion resistance and hardenability better.
• Vanadium: Enhances wear resistance by forming hard carbides in the steel structure.

To make sure quality is consistent, HSS production must meet strict global standards like ASTM A600 and ISO 4957. These standards set clear rules for its chemical makeup, hardness and performance. This is important for industrial users who need reliable tool performance.

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Core Properties of HSS

Red Hardness

HSS maintains a sharp cutting edge even at high temperatures, up to 600°C or higher. This property provides a key advantage for high-speed machining: cutting metal generates significant heat, and while most other steels soften and lose sharpness quickly under such conditions, HSS does not. Stable cutting quality and efficiency are thus guaranteed.

High Toughness

With strong resistance to chipping and fracture, HSS is ideal for interrupted cutting， a process in which the tool repeatedly enters and exits the workpiece (e.g., machining grooved or holed workpieces). In these scenarios, tools endure frequent shocks, and HSS’s toughness allows it to withstand such impacts without damage.

Easy to Resharpen

HSS tools can be easily sharpened when they get dull. This could extend their service life and reduce the need to purchase new tools. For industrial users, this means lower replacement costs and improved tool utilization.

Cost-Effectiveness

It is cheaper compared with high-end cutting materials such as carbide or ceramic. Additionally, the long service life of HSS helps reduce long-term maintenance costs, making it a cost-effective choice for most industrial machining applications.

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Main Types of HSS

HSS can be divided into three major categories based on alloy composition and performance. Each type of HSS is of distinct characteristics and application scenarios:

Tungsten-Based HSS (T-Series)

Tungsten-Based HSS contains high tungsten content. T-Series HSS can deliver excellent red hardness, wear resistance, and thermal stability. It is Ideal for high-temperature cutting of carbon steel and alloy steel. Typical uses include making lathe and planer tools, as well as other general-purpose cutting tools.

• Typical grade: T1 (W18Cr4V), a classic universal grade.

Molybdenum-Based HSS (M-Series)

Dominated by molybdenum as the main alloy element, M-Series HSS is the most versatile HSS category, including two key subtypes:

• Tungsten-Molybdenum Type (e.g., M2/W6Mo5Cr4V2)

This type accounts for almost 70% of the total global HSS. Tungsten-Molybdenum HSS balances toughness, wear resistance and cost-effectiveness perfectly. It is widely used in drilling, tapping, gear cutting and other common machining scenarios.

• High-Vanadium Type (e.g., M3/W6Mo5Cr4V3)

Classified under the M-series by ASTM, High-Vanadium HSS is a high-vanadium variant. Vanadium carbides bring superior wear resistance. It is suitable for applications such as machining titanium alloys and other hard-to-cut materials that require high wear resistance.

High-Performance HSS (HSSE, also called HSS-E)

HSSE is an upgraded version of standard HSS, defined by ISO 11054. HSSE has enhanced high-temperature performance. It includes two main subtypes:

• Cobalt-Enhanced Type (e.g., M35, M42)

HSSE that contains 5-8% cobalt, significantly improving red hardness (maintains sharp edge at up to 600°C). It is widely used in the aerospace and automotive industries, especially for processing stainless steel, nickel-based alloys and high-temperature alloys.

• Aluminum-Containing Type (e.g., 501/W6Mo5Cr4V2Al)

A China-developed variant (meets GB/T 17111, aluminum content ≥0.8%). This type of HSSE could also offer excellent red hardness (similar to cobalt-enhanced HSSE), but it costs less. It is a more cost-efficient choice for SMEs processing hard materials.

HSS Types Comparison Table

Each HSS type is tailored to specific machining needs. Choosing the right type depends on factors like workpiece material, machining temperature and budget constraints.
The following comparison table summarizes key information for quick reference:

Type	Typical Grade	Hardness	Red Hardness	Key Advantage	Application Scope
Tungsten-Based	T1 (W18Cr4V)	62-65 HRC	500℃: 52 HRC	Good thermal stability; easy to grind	General drills, lathe tools; high-temperature cutting of carbon steel and alloy steel
Molybdenum-Based – Standard	M2 (W6Mo5Cr4V2)	63-66 HRC	550℃: 54 HRC	Best cost-performance; accounts for ~70% of global usage	All-purpose machining (end mills, taps, gear cutting)
Molybdenum-Based – High-Vanadium	M3 (W6Mo5Cr4V3)	65-67 HRC	550℃: 55 HRC	Superior wear resistance	Titanium alloy machining; hard-to-cut materials requiring high wear resistance
HSSE – Cobalt-Enhanced	M35, M42	66-70 HRC	600℃: 55 HRC	Excellent red hardness	Stainless steel, nickel alloy machining; aerospace and automotive industries
HSSE – Aluminum-Containing	501 (W6Mo5Cr4V2Al)	66-67 HRC	600℃: 54 HRC	Low-cost alternative to cobalt-enhanced HSSE	Budget-sensitive hard material machining for small and medium-sized businesses
PM HSS – Powder Metallurgy High-Speed Steel	ASP-60, S390	67-70 HRC	600℃: 56 HRC	Uniform structure; 2-3x longer service life	Heavy-load precision machining (large gears, high-precision molds)

Key Applications of HSS

HSS is a key material for cutting tools. It is widely used in many industries because of its good balance of red hardness, toughness, and cost-effectiveness. The main uses of cutting tools and related industries are as follows:

General Machining Cutting Tools

HSS is the primary material for the most common cutting tools. It can handle high temperatures and frequent shocks during general machining. Common machine tools include drills, end mills, taps, reamers and lathe tools. For example, M2-grade HSS is widely used to make twist drills. These drills make holes in carbon steel and alloy steel.

Automotive Industry

The automotive industry uses many HSS cutting tools. These tools are used to process engine parts, transmission parts and chassis parts. For example, engine cylinders, crankshafts and camshafts are often made of hard alloy steel or cast iron. HSSE-Cobalt-Enhanced cutting tools (like M35 and M42) are the best choice for this processing due to their good red hardness and toughness.

Aerospace Industry

Suitable for hard-to-cut materials (stainless steel, nickel-based alloys, titanium alloys). High-performance HSS (HSSE) and PM HSS play a cricial role in Aerospace industry. For example, HSSE and PM HSS tools are used for engine blades and structural parts. PM HSS is also used for heavy-load precision machining of large aerospace parts.

Small-Batch & Custom Fabrication

HSS cutting tools are a cost-effective choice for small workshops. HSS tools are cheap and easy to resharpen. This reduces the cost of buying new tools for small businesses. For example, aluminum-containing HSSE (Grade 501) is a good choice for cutting hard materials with a tight budget.

Interrupted Cutting Scenarios

Perfect for jobs where tools enter/exit workpieces repeatedly (e.g., grooved parts, irregular shapes). HSS milling cutters and planer tools stand repeated shocks without breaking or chipping.

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HSS vs. Other Cutting Materials

The selection of the right cutting materials directly affects the efficiency of the machining, tool cost and product quality. To help distinguish the difference between common cutting materials, the table below compares the performance of HSS, Carbide and Ceramic/CBN from many perspectives.

Comparison Dimension	HSS	Carbide	Ceramic/CBN
Toughness	Good	Poor	Very Poor
Shock Resistance	Good	Poor	Very Poor
Total Cost	Low (easy to resharpen, long service life)	Medium-High (hard to resharpen, need frequent replacement)	High (brittle, easy to break, high replacement cost)
Suitable Production Batch	Small-batch & mass production	Mass production	Mass production
Workpiece Uniformity Requirement	Low (no strict requirement)	Medium	High (strict requirement)
Suitable Machine tools	General-purpose machine tools (like regular lathes or milling machines)	High-speed precision machine tools	Ultra-precision, high-rigidity machine tools
Core Advantage	Balanced performance; cost-effective; versatile	High hardness; good wear resistance	Extreme high-temperature resistance; excellent wear resistance for hard materials

结论

To sum up, high-speed steel (HSS) has been a top choice for cutting tools for decades. It has good red hardness, high toughness, easy resharpening, and cost-effectiveness. Different types of HSS fit different needs, from general machining to high-precision jobs in automotive and aerospace industries. In the future, HSS will continue to play a key role in the machining industry. For more information about high-speed steel, please feel free to contact SUMEC Metal.