AISI 01 tool steel

Heat treating 01 tool steel for knives

Forging:

Start forging at 1800 to 1950 °F (980 to 1065 °C). Do not forge below 1550 °F (845 °C)

Normalizing: Heat to 1600 °F (870 °C). cool from temperature in still air.

Annealing: Heat to 1400 to 1450 °F (760 to 790 °C). Use lower temperature for small sections and higher tem­perature for large sections.
Cool at a maximum rate of 40 °F (22 °C) per hour.
The maximum rate is not critical after cooling to below 1000 °F (540 °C).

Grinding or Machining

Stress Relieving (optional): Heat to 1200 to 1250 °F (620 to 650 °C) Cool in air.

Hardening: Aus­tenitize at 1450 to 1500 °F (790 to 815 °C) for 10 to 30 min, then quench in oil.
Quenched hardness, 63 to 65 HRC
Tempering: Temper at 350 to 500 °F (175 to 260 °C)

Graphic from Cashen Blades

 

Stock Removal

Annealing: Annealing is not typically required since the steel comes from the supplier ready to be heat treated.

Grinding or Machining

Stress Relieving (optional): Heat to 1200 to 1250 °F (620 to 650 °C) Cool in air. If you have over heated the steel in any way at all then a normalizing routine can be added into the heat treating routine.

Hardening: Aus­tenitize at 1450 to 1500 °F (790 to 815 °C) for 10 to 30 min, then quench in oil.
Quenched hardness, 63 to 65 HRC
Tempering: Temper at 350 to 500 °F (175 to 260 °C)

NOTES:

Hamon on 01 steel is generally not possibly due to the fact it is a through hardening steel and will achieve full hardness even in a slow quench oil. You can experiment with high heat mortar with sodium silicate and aluminum oxide powder and edge quench only.

 

This steel like all tools steels should be protected during heat treating to prevent decarburization. This can be done with clay, tool wrap or a anti-scaling paint.

This is not a steel to ever quench in water as it will shatter very quickly. Once the nose of the cooling curve passes the 5 second mark water or brine are not recommended.