CPM® M4® Carbon Steel

M4 Heat Treat Information:

Preheat: Heat to 1,500-1,550°F. Equalize temperature. Second pre-heat stage at 1,850-1,900°F suggested for vacuum or atmosphere hardening.

Austenitize: It is critical to not exceed the maximum austenitize temperature. If you overshoot the maximum temperature by a small amount, toughness will go down dramatically.

1,875-2,200°F. Hold time at temperature: 1,875°F - 45 minutes

For cutting tools use 2,150-2,200°F. For cold work applications use 1,875-2,125°F. Quench in air or positive pressure quench to below 125°F, or salt or interrupted oil quench to about 1,000°F, then air cool to below 125°F. A fast quench rate from hardening temperature to below 1,100°F is critical to achieve optimum heat treat response. A slower cooling rate below 1,000°F may be used to minimize distortion.
Temper: Double temper at 1,000°F minimum. Triple temper recommended when hardening from 2,100°F or higher. 2 hours minimum each temper. Air cool to room temperature between tempers.

Cryogenic Treating: After the first temper may improve long term dimensional stability by transforming retained austenite. Any cryogenic treatment must be followed by a temper.

Use the graph below to select your temperatures:

CPM M4 Chemical Composition

1. Click on the button below to get the chemical composition of the steel you purchased.
2. You will be required to enter the three character code written in red letters on your steel.
3. If you do not see red letters on the steel, your specific chemical composition is not in the system.

Chemical Composition