Goal:
By nitriding, the surface is very hard and abrasion resistant. Due to the low annealing temperature (up to about 500 ° C), the torsion is very small in the work piece and there is no tension due to the removal of the quench operation.
Application:
Nitrified steels are used in tooling to make a variety of orders, as well as die-casting molds, synthetic materials, rubber, injection molds, thermoplastic materials, continuous-material extrusion molding components and injection molding machines.
The stability, aging and corrosion of the nitrified steel, as well as abrasion resistance and good slip properties (low coefficient of friction), make the application of this steel better.
Method:
In the Nitrified process, alloys of chromium, aluminum and sometimes nickel alloys are annealed up to 520-500 degrees Celsius in the course of ammonia gas flow. Of course, this can be done at a temperature of 550-570 degrees Celsius in a molten bath of cyanide salt. In this annealing operation, nitrogen penetrates the surface of the work piece and, due to the bonding with the alloying elements, the hardness of surface is increased extremely. With this method, it’s possible to achieve a Wickers 1000 HV, which is equivalent to a Rockwell hardness of 68 HRC. If parts of the piece of work are to remain soft, these parts are covered with tin plated work.
The thickness of the nitrified layer depends on the duration of the annealing, the nitrified method (nitrified salt bath, nitrous gaseous), and the type of nitrified steel a few tens of millimeters. The disadvantage of this is the long-term annealing. The time required for the hardening depth is about 0.1 mm in a nitrified bath salt, and the gas is 2 and 8 hours, respectively.
Since hardening (gradient) changes from the surface of the work piece to the brain are slow, the hardening process is difficult. However, avoid creating sharp edges and thin layer in the work piece, since in these cases the nitrified action is performed on both sides, the brains do not remain stiff and soft. In thin sheet parts, the edge of the parts is round and the length of the nitrified steel is shortened. refining of steels is very beneficial, because in refining, mechanical properties are better, and it is necessary to create a perfectly refining structured nitrified layer.
