Nickel foil

Nickel foil made of the material 2.4066 

As a diffusion barrier: The position of the alloy element in the steel is not unchangeable. At elevated temperatures, the elements diffuse and strive for equalization or a homogeneous distribution. The higher the temperatures, the faster the elements diffuse. Carbon is the element that diffuses the fastest by far. Carbon diffusion also takes place when two steels with different carbon contents are fire-welded together. E.g. with 3-layer blades. As a rule, carbon migrates from the higher carbon core steel to the lower carbon side layers during fire welding, forging as well as during the subsequent heat treatment. Depending on the material thickness, the temperature and the holding time, the core layer can become heavily decarburized, which greatly reduces the performance of the cutting edge. This effect is particularly serious if the cutting layer is not perfectly centered and some of the side layers move close to the cutting edge. Since carbon diffuses through nickel many times more slowly than through iron, this effect can be greatly reduced with a thin layer of nickel between the core material and the side layers. 

In decorative damascus steel: Nickel has excellent corrosion resistance and resistance to a large number of alkalis and acids. In damascus steel, nickel is extremely bright (silver) and does not form a gray patina even with prolonged use. However, since nickel cannot be hardened, it is not suitable for use in high performance damascus steel. Very light lines appear optically dominant in damascus steel. I therefore recommend only using thin layers of nickel that are 1/10 to 1/5 the thickness of the dark layers. In order to achieve a suitable material thickness, several thin layers of nickel can be placed on top of one another. For a non-hardenable decorative damascus steel with an extreme light-dark contrast, I recommend the combination with the fine-grain structural steel 1.8974 / S700. 

Nickel can be easily fire-welded. Both "classic" in the forge fire with the help of a flux, as well as in fire welding with the exclusion of oxygen. The nickel foil is bare metal and can be used directly. The foil can be cut with strong scissors. 

Nickel can be used to simplify fire welding of problematic materials. For example, if you want to produce a 3-layer construction with a core made of 1.2063 and side layers made of 1.2767, this can lead to difficulties with conventional fire welding in a forge. Both steels have an increased chromium content, the oxides of which hinder fire welding. If you put a thin layer of nickel between the steels, fire welding is made much easier. 

Attention: Nickel should not be used if the processor or the future user suffers from a nickel allergy. In the case of commissioned work, e.g. in the kitchen knife area, this should be clarified in advance. The fumes that arise when nickel is welded with TIG, MAG or electrodes are poisonous. It is essential to ensure adequate ventilation and extraction of the welding gases.