One of the main requirements that apply to detail in the production is its strength and durability. Nitriding steel is one of the most effective methods of improving such characteristics. Nitriding is a treatment in which the surface is saturated with nitrogen. The process occurs in an ammonia environment while heating to 480-650 °C. As a result stands out atomic nitrogen, which absorbs the surface of the steel. Mainly used medium-carbon alloy steels that contain Cr, W, Mo, V, Al, for which the nitrogen forms stable nitrides. In this case, after nitriding, the surface layer has high hardness up to 1100-1200 HV.Depending on the requirements, choose different types of steel grades. For example, if the surface should have a high hardness and wear resistance, nitriding choose steel, having in its composition aluminum (most commonly used steel 38ХМЮА).
Nitriding of steel takes place in several stages. Initially, the part is subjected to improvement in heat treatment, which consists in quenching and high-temperature tempering. The next stage is machining, which allows you to give the details of the final dimensions.
Before the final stage on those parts of products that need to be protected from nitriding covered by a thin layer of tin or liquid glass. Nitriding steel, depending on the mode (single or double) usually takes 24-90 hours. The result is a layer thickness of 0,3 – 0,6 mm. It is worth to note that during the nitriding treatment is possible the deformation (warping) of the part: deformation more than that higher temperature, deeper layer of nitriding and thinner wall products. Our company provides the service of nitriding steel in Kiev. Contact us, you for the low price get the product, which has high hardness, wear resistance, endurance limit, corrosion resistance and high-temperature strength.
Since ancient times, thermal treatment is the most used technology changes the structure of metal: the item can be made mild, or Vice versa, will greatly increase its strength. The process of heat treatment, which increases the strength of the sample is called hardening. All types of hardening, the highest quality is volumetric hardening. It changes the whole structure of the product, as the volumetric hardening provides for heating not only the surface but also the deep layers of the metal. As a result of complex procedures, the item receives a high wear resistance and hardness, as well as the specified characteristics. Depending on the structure of what steel it is necessary to distinguish used several methods of volumetric hardening: for carbon steels used for continuous cooling in water, and for alloyed stells – in oil. The technology is as follows: preheated part is immersed into the quenching medium and kept there until completely cooled.
Hardening of carbon steels is produced with reduced requirements to mechanical properties of the core. These steels provide high tensile strength (for wall thickness 40 mm rupture strength > 80 kgf/sq mm), but the impact strength are low. Carbon steel is used for simple parts that can be cooled in water.To do this, take steel grade not lower than 40-45.
In the volumetric hardening of parts of complex structures in the aquatic environment, there are internal stresses that lead to cracking: due to insufficient hardenability, the hardness on the cross section comes out uneven. Note that the probability of occurrence of cracks is directly proportional to the required hardness - if higher the hardness, the more can be cracked. So the details which deformation unacceptable are made of alloy steel (steel quality SH-15, 40X, 65G). Their mechanical properties provide better hardenability and cooling in oil.