M2 tool steel is a highly versatile, general-purpose high-speed tool steel that provides a good balance of toughness, wear resistance, hot hardness, and heat treatability, making it suitable for a broad spectrum of cutting, forming, and structural applications.

1. Applications

• General-Purpose Cutting Tools
• Single-Point Cutting Tools: They can machine a wide range of materials, including wrought steel, cast steel, cast iron, brass, bronze, copper, and aluminum.
• Drills: M2 material is the universal choice for general-purpose drills.
• Milling Cutters: More than 70% of free-machining milling cutters are made of M2 material.
• Saws: M2 high-speed tool steel is the general-purpose saw material.
• Other Applications: M2 hss is used as a core and ejector pin material in plastic injection molding tools. Also used for structural applications, such as machine elements, cams, shafts, spindles, gears, and sprockets.

2. M2 steel composition

3. M2 Tool Steel Properties

M2 tool steel stands as a cornerstone in the high-speed steel (HSS) family, and for many good reasons, it’s a popular choice for a wide array of demanding applications. This molybdenum-based HSS, part of the “M” series, delivers a reliable combination of hardness, wear resistance, and toughness, making it a versatile workhorse.

3.1 Hardness

The M2 tool steel hardness is very high, and through hardening and tempering, its working hardness ranges from 60 to 65 HRC.

3.2 Wear Resistance

Extremely high wear resistance.

3.3 Hot Hardness (Tempering Resistance)

Good thermal hardness, meaning that it can maintain its hardness and strength even under high-temperature working conditions. While some specialized HSS grades might offer higher hot hardness, M2 material performs reliably in typical high-temperature tooling scenarios.

3.4 Toughness

M2 steel has such high hardness and wear resistance while maintaining good toughness. Tool steel M2 produced by powder metallurgy (P/M) processes has higher toughness.

3.5 Physical Properties

3.6 Mechanical properties

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4. Heat Treatment

M2 steel can only achieve the required performance through proper heat treatment. The primary objective of M2 tool steel heat treatment is to transform M2 steel from a softened, annealed state (mainly composed of ferrite and alloy carbides) into a hardened and tempered martensitic structure, in which carbides are distributed in an optimal position to meet the necessary cutting performance requirements.

The typical heat treatment sequence for M2 tool steel involves the following stages:

4.1 Preheating

Preheating of materials should be carried out in stages to minimize the risk of thermal shock, especially when there are significant differences in the cross-section of parts. If the furnace is first heated to 650°C (1200°F), we can place M2 parts on the top of the furnace to remove any chill and then place it in the furnace. This helps to reduce thermal shock and lower the risk of cracking. It is then placed in the furnace and kept there for about 10-12 minutes.

4.2 Hardening（Austenitizing） 

The hardening temperature for M2 tool steel typically ranges from 1190°C to 1220°C (2175°F to 2225°F). Some references cite up to 1230°C (2250°F). The soaking time at the final hardening temperature for M2 high-speed steel is relatively short, only a few minutes, depending on the part’s size and furnace efficiency. 

4.3 Quenching

The quenching medium can be air, oil, or salt. Oil quenching works well for M2 steel parts with a cross-section of up to about 1 to 1.5 inches (25-38 mm). The martensitic transformation begins at about 316°C (600°F) and is completed at about 93°C (200°F). We recommend cooling M2 parts to approximately 65°C (150°F) after quenching, then proceeding to the next step of tempering.

4.4 Tempering¹

Tempering is performed on M2 high-speed steel after quenching to relieve internal stresses, enhance toughness, and promote secondary hardness. This involves reheating the steel to an intermediate temperature below its critical transformation temperature.

M2 high-speed tool steel requires 2 to 4 tempering cycles at a temperature of at least 540°C (1000°F), typically 3 cycles.

For example, after austenitizing at 1230°C (2250°F), the first tempering cycle is performed at 565°C (1050°F), followed by the second at 550°C (1025°F), and the third at 540°C (1000°F).

For each tempering cycle, the soaking time is 2 hours per inch (25 mm) of the thickest cross-section. After the first tempering, the M2 steel component must be completely cooled to room temperature before the next tempering can be performed.

Tempering M2 material transforms retained austenite into fresh martensite, precipitates complex carbides, and significantly contributes to the steel’s secondary hardness. Multiple tempering cycles refine the microstructure, enhance wear resistance, and further relieve stresses.

It is important to note that M2 steel must not be undertempered.

Additionally, we recommend performing stress-relief tempering after subsequent processes such as grinding, welding, or electrical discharge machining (EDM), with the tempering temperature set 14–28°C (25–50°F) below the final tempering temperature.

Hardness-Tempering Temperature Relationship Table for M2 Steel

5. Equivalent grades

• USA (AISI/ASTM): M2 (This is the primary designation)
• Germany (DIN/W-Nr): 1.3343, HS6-5-2
• Japan (JIS): SKH51
• Britain (BS): BM2
• China (GB): W6Mo5Cr4V2
• ISO: HS 6-5-2
• France (AFNOR): Z85WDCV06-05-04-02
• Sweden (SS): 2722
• Russia (GOST): R6M5

6. D2 Vs. M2 steel

In industrial production, we often compare D2 tool steel and M2 tool steel. The comparison data for these two steels is provided in the table below for reference.

7. Supply forms and dimensions

The M2 tool steel we supply is available in various shapes, including round bars, sheet plates, slabs, flat bars, square bars, and blocks. The dimensions of the flat bar range from: width 20–600 mm × thickness 20–400 mm × length 1,000–5,500 mm. The dimensions of the round bar range from a diameter of 20–400 mm × a length of 1,000–5,500 mm. The block dimensions are obtained by cutting the flat bar.

For smaller sizes, such as round bars with a diameter less than 70 mm, we use the hot-rolled process. For sizes greater than 70 mm, we offer forged products.

UT testing: Sep 1921-84 D/d, E/e. 

Surface Treatment: original black, peeled, machined/turned, polished, grounded, or milled surface finishes.

Inventory Status: We do not maintain a stock of M2 steel. We arrange production based on customer orders.

Delivery time: Electric Arc Furnace (EAF) materials are 30-45 days.