A hardened blade is at the very heart of a knife. Without that, all you have is a very pretty paperweight.
Note: This is intended as a guide only. The heat treat you use is to enable the full functioning of the knife in the intented application or use in the field. A knife that requires a high hardness will inherently be “more” brittle. A knife that needs more toughness, won’t hold an edge as well but will also be easier to sharpen.
We recommend the following heat-treating regime for hardening our DSC® Inox damascus steel:
Where possible, it’s best to complete the austenitization in a vacuum, protective gas environment, wrapped as tightly as possible in .002 stainless steel foil (KNU-FOIL available from KMTS) or painted with a heat resistant paint (Condursal Z1100 from Stan Hohowsky). Use double folds on all sides to ensure a tight seal.
- Preheat your furnace to austenitizing temperature – 1000-1030°C (1832 – 1886°F). Tested by Stefan Diedericks
- Place your protected piece in the furnace.
- Allow your furnace to cycle back up to austenitizing temperature.
- Soak your piece for 15-20 minutes (depending on the thickness of the piece). NB! We have found a longer soak time is crucial to obtaining the best hardness.
- Rapidly quench in oil (until it stops smoking) or air (plate quench) until cool to the touch.
- Immediately deep freeze. Deep freezing after hardening is not required but is recommended for stainless steel. (Note, that the steel should have reached room temperature before submerging in your chosen cold treatment medium to avoid cracking)
The maximum corrosion resistance is achieved after hardening.
Tempering after the hardening process is required to convert the steel structure into tempered martensite and to adjust its hardness/toughness.
We recommend two separate tempering cycles with a duration of at least 1 hour, optionally repeating the deep freezing process (liquid nitrogen for 4 hours) before the second tempering.
- For knife blades (60-61 HRC): 2 x 1 hour at 150-180°C (302-356°F)
- For decorative items (56-57 HRC): 2 hours at 300°C (572°F)
Note A high tempering temperature (eg >500°C) can negatively impact the stain-resistant properties of the steel and should only be used when using the higher austenitizing range.
Please note that a new unique material is created through the forging of the Damascus steel which has its own hardness profile, compared to that of the two original steels.