A particle metallurgy carbon steel made by several manufacturers.
This steel gets very sharp. Its edge holding is excellent. If you use M4 to make a knife do most of your finishing before heat treating because it is very hard to finish after.
I think M4 has gotten much more popular since it has been used in cutting competitions.
Vanadis 4 Extra is shown in the table above for comparison purposes.
Heat Treating Information:Preheat: Heat to 1500-1550°F, equalize. Second pre-heat stage at 1850-1900°F suggested for vacuum or atmosphere hardening.
Austenitize: 1875-2200°F. Hold time at temperature: 1875°F - 45 minutes
1975°F - 30 minutes
2050°F - 20 minutes
2100°F - 15 minutes
2150°F - 10 minutes
2200°F - 5 minutes
For cutting tools use 2150-2200°F. For cold work applications use 1875-2125°F. Quench in air or positive pressure quench to below 125°F, or salt or interrupted oil quench to about 1000°F, then air cool to below 125°F. A fast quench rate from hardening temperature to below 1100°F is critical to achieve optimum heat treat response. A slower cooling rate below 1000°F may be used to minimize distortion.
Temper: Double temper at 1000°F minimum. Triple temper recommended when hardening from 2100°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.
Heat Treating Services:
Blade Steel Information & Composition
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