Start knife after forging

The steel of a knife blade is heated during forging, which gives it its hardness. Quenching in an oil bath produces the hardened blade steel, which, however, is not yet usable. The high brittleness and internal stresses must be eliminated by a dosed and uniform reheating when starting.

Metered and controlled cooling

Hard materials, which are brought into a malleable processing state by heating, are not ready for use after cooling. In the case of glass and metals, tensions and chemical-physical reactions occur during the cooling process which lead to brittleness and breakage sensitivity. Controlled reheating in the cooling phase prevents or neutralizes these processes.

In the blown glass body, the stepwise cooling in a curing oven is required. Steel blades from Messer are also dosed in an oven. This tempering should start immediately after quenching. Complete warm-up is the condition at start-up to "calm down" the material molecules. The hardness of the blade decreases, which should be considered when choosing the steel or alloy.

This is how the tempering works

The hot knife, freshly quenched in an oil bath, is transported into the tempering furnace without delay. As a furnace, in principle, any type of oven in question, in which a targeted and controllable temperature can be generated. If this temperature control is possible, a forge fire can also be used for starting.
The blade of the knife is placed in the already preheated oven or fire. Before that, the so-called scale layer resulting from the forging and quenching process has to be roughly removed with emery paper of grain size 120 to 200. The knife blank is placed on a base with as few support points as possible. The stove must deliver top and bottom heat to the same extent.

Check the process

On average, starting a knife blade takes one to two hours. As a reference temperature 200 degrees Celsius can be selected. The observation of the color development of the steel is used to control and optionally readjust the temperature. Ideal is straw yellow to golden yellow color. If the color darkens, the temperature must be lowered. The usual knife steels move in the tempering temperature range between 160 and 230 degrees Celsius.

Tips & Tricks

If you use corrosion-resistant and corrosion-resistant steel, temperatures of up to 500 degrees Celsius may be required for tempering.

Video Board: Forging a Knife - EVERY SINGLE STEP