Heat Treating Knives Media
Published: 6 years ago
https://northarmknives.com/
Even the the best knife making steels are nothing without a good heat treatment. Heat treating is the process of taking a steel blade in it's soft state ( annealed), and hardening it. This is done by heating it to a critical temperature, (which varies dependent on the steel grade) and then cooling it very quickly to room temperature. The steel we use (cpm s35vn) needs to be heated to between 1900 and 2000 Fahrenheit.
We use an electric oven (or kiln) and we shoot for 1960F. Once the blades have soaked at that temperature for 15 or 20 minutes, we take them out and quench them between aluminum plates. This cools them to room temperature within 2 minutes!
After the quench, the knives go into what is called a sub-zero quench, which means we put them into dry ice to cool them to approximately -100F. This helps to finalize the hardening process. After coming out of this step, the knives are very hard but also very brittle.
The final stage of the process is tempering. This step makes the knives a bit less hard and a lot less brittle. For tempering we heat the knives to 600F and hold them there for 2 hours. Then we remove them from the kiln and let them cool to room temp. We repeat that process a second time and the blades are finished. The steel is now nice and hard yet tough and will hold an edge well without being too delicate. The final hardness is between 59 and 61 HRC (hardness as measured on the Rockwell C scale.)
Hope you enjoy the video!
Thanks for watching.
Mike & John
https://northarmknives.com/
Even the the best knife making steels are nothing without a good heat treatment. Heat treating is the process of taking a steel blade in it's soft state ( annealed), and hardening it. This is done by heating it to a critical temperature, (which varies dependent on the steel grade) and then cooling it very quickly to room temperature. The steel we use (cpm s35vn) needs to be heated to between 1900 and 2000 Fahrenheit.
We use an electric oven (or kiln) and we shoot for 1960F. Once the blades have soaked at that temperature for 15 or 20 minutes, we take them out and quench them between aluminum plates. This cools them to room temperature within 2 minutes!
After the quench, the knives go into what is called a sub-zero quench, which means we put them into dry ice to cool them to approximately -100F. This helps to finalize the hardening process. After coming out of this step, the knives are very hard but also very brittle.
The final stage of the process is tempering. This step makes the knives a bit less hard and a lot less brittle. For tempering we heat the knives to 600F and hold them there for 2 hours. Then we remove them from the kiln and let them cool to room temp. We repeat that process a second time and the blades are finished. The steel is now nice and hard yet tough and will hold an edge well without being too delicate. The final hardness is between 59 and 61 HRC (hardness as measured on the Rockwell C scale.)
Hope you enjoy the video!
Thanks for watching.
Mike & John
https://northarmknives.com/