How to Heat Treat O1 Steel

American Iron and Steel Institute grade O1 tool steel is a high carbon, high alloy steel designed to be machined and quenched in oil. It is composed of iron, carbon, manganese, chromium, silicon and tungsten. It is known for excellent wear resistance, toughness and hardness. Because the steel is so tough, it can be difficult to machine without properly heat treating it to anneal it. This is followed by a hardening process and tempering to produce a finished, hardened part.

O1 steel should be heat treated to prepare it for machining.

Step 1

Preheat the oven to 1,250 degrees Fahrenheit. Let the steel warm in the oven until it reaches the preheated temperature. Raise the temperature to 1,450 degrees and let it soak for at least 45 minutes.

Step 2

Lower the temperature by no more than 50 degrees each hour until it reaches 900 degrees Fahrenheit. Turn off the furnace and allow the steel to cool to room temperature to anneal.

Step 3

Place the steel in an oven set at 1,475 degrees Fahrenheit. Let it soak for at least an hour. Remove the steel and quench it in oil until it reaches room temperature and is cooled. This will produce a part with uniform hardness. Temper the steel by raising its temperature to 350 degrees and letting it cool in the air.


  • the process of heat-treating steel requires extremely high temperatures. Proper safety equipment and procedures must be followed to prevent serious injury.

About the Author

Writer, photographer and world traveler James Croxon is a jack of all trades. He began writing in 1998 for the University of Michigan's "The Michigan Times." His work has appeared in the "Toronto Sun" and on defenselink.com and globalsecurity.org. Croxon has a bachelor's degree in English from the American Military University.