The thermal treatment, known as hardening or tempering, is a fundamental aspect in the behavior of every piece of steel.
The steel must be hardened to enhance their qualities, this treatment involves four basic steps: normalized after grinding; hardened when the piece is almost finished with a medium polishing, sub-zero treatment to precipitate the retained austenite and complete the hardening, and finally one or more tempering to ease tensions and lower the hardness to the desired values.
The qualities achieved will depend on the tests that have been made with each steel and the strictness with which they perform the process that has achieved the best result.
Support with three Arkansas stones of different grains, coarse, medium and fine.
Pocket sharpener. Useful and practical.
In our case we want is to hardened the blade so that its cutting edge is more durable.
A harder cutting edge will have a more lasting, but spend more time on his resharpening. With a lower hardness will recover the cutting edge quicker but also lose it very rapidly.
The hardness that the great masters have been established as the most balanced is 60 Rockwell "C".
With this hardness we have very good durability cutting edge and not be very difficult resharpening.
Until that blade hardness, we can sharpen with a good natural stone or a steel sharpener of thin grooves.
Test piece of ATS 34, hardened to 61 RC which has exceeded the bending moment and has been deformed without breaking. Below another test piece: SAE 5160, that has broken after having achieved a significant deformation.
There are also sharpening stones and ceramic sharpener, or better yet, diamond dust. With these elements (ceramic or diamond dust) can resharpening a knife easily hardened to over 60 RC.