PM M4 This high-speed tool steel epitomizes versatility, boasting an extraordinary blend of high wear-resistance, superior impact toughness, and remarkable bend strength. These attributes stem from its fine grain size, minuscule carbides, and exceptional cleanliness. PM M4 delivers superior cutting tool longevity when compared to traditionally-wrought M1, M2, M7, and other lower-alloyed high-speed steels. PM M4 outperforms high-carbon, high-chromium die steels like D2 and D3 in cold work tooling applications.

Other Known Names: CPM REX M4 steel ^® , ASP 2004, S690

Common Usage

Ideal for Broaches, End Mills, Punches, Hobs, Fine Blanking, and Forming Dies.

Physical Properties

Density:

³ (7806 kg/m ³ )

Specific Gravity:

7.92

Modulus Of Elasticity:

31 x 10 ⁶ psi (214 GPa)

Machinability:

40-45% of 1% carbon steel

PM M4 High Speed Steel Chemical Composition

PM M4 High Speed Steel Heat Treating

PM M4 High Speed Steel Thermal Treatments

Heat rapidly from the preheat stage.

For Cutting Tools:

• Soak for 5 to 15 minutes.
• Furnace: 2150-2175°F (1177-1191°C)
• Salt Bath: 2125-2175°F (1163-1191°C)

For Cold Work Tooling:

• Soak for 20 to 45 minutes.
• Furnace: 1875-2125°F (1023-1163°C)
• Salt Bath: 1850-2100°F (1010-1149°C)

To maximize toughness, opt for the lowest temperature. For optimal hot hardness, select the highest temperature.
Quenching:
Utilize pressurized gas, warm oil, or salt.

For pressurized gas, the furnace should maintain a minimum quench pressure of 4 bars. Achieve a quench rate of roughly 400°F (222°C) per minute down to below 1000°F (538°C) to secure the desired properties.

For oil quenching, quench until black (about 900°F or 482°C), then let cool in still air to 150-125°F (66-51°C).

To maintain optimal salt conditions, hold the temperature steady at 1000-1100°F (538-593°C). Let the material equalize in the salt bath, then allow it to cool in still air until it reaches 150-125°F (66-51°C).

Tempering:

Begin tempering immediately after quenching to preserve the material's properties.
The recommended tempering temperature range is 1000-1100°F (538-593°C). Ensure not to temper below 1000°F (538°C). Maintain the material at the tempering temperature for 2 hours, followed by air cooling to ambient temperature. Double tempering is essential, and triple tempering is mandatory when austenitized at 2100°F (1149°C) or higher.

Annealing:

Annealing should be performed post hot-working and prior to re-hardening to ensure material stability.

Heat the material at a controlled rate not exceeding 400°F per hour (222°C per hour) until reaching 1550-1600°F (843-871°C). Maintain this temperature for a minimum of 2 hours, or 1 hour per inch (25.4 mm) of thickness. Gradually cool with the furnace at a rate not exceeding 50°F per hour (15°C per hour) until it reaches 1000°F (538°C). Continue cooling to ambient temperature, either in the furnace or in open air.