Nitriding is another thermochemical heat treating process. Instead of boron, nitrogen is used to improve surface properties such as hardness and wear resistance. Nitrogen reacts with the iron and other alloys on the surface, forming strong nitrides that protect the surface of the material.
Boriding vs. nitriding – A comparison
Both boriding and nitriding improve mechanical properties and wear resistance. However, in this article we are comparing these two heat treating processes:
- Steel grades: Nitriding works best on so-called “nitriding steels”. These types of steels contain a significant amount of alloys that can form nitrides with the nitrogen, such as molybdenum, titanium, chromium and aluminum. Therefore, steel grades that do not contain a sufficient amount of these alloys are not fit for nitriding. Boronizing on the other hand, can not only be used with the same type of steel grades as nitriding, it can also be applied to steel grades containing nickel, nickel superalloys and cobalt superalloys. Nickel, in particular, is one of the most widely spread alloys due to its excellent wear and corrosion resistance. Most stainless steels today contain nickel, making boriding a great choice for almost any type of stainless steel.
- Hardness: Depending on the base material, boriding with BoroCoat® can increase surface hardness up to 2600 HV. Nitriding can only reach up to 950 HV for certain steel types.
- Wear resistance: Both boronizing and nitriding provide protection against wear, corrosion and impact damage. The diffusion layers that are formed act as barriers between the core material and the environment. However, the performance of materials that were borided by means of special treatments such as BoroCoat® are far superior to nitriding because the protective boride layer is not only harder, but also more resistant to acids and other chemicals.
- Thermal stability: Our BoroCoat® layers display excellent stability at extreme temperatures up to 1000 °C.
- Coating or diffusion layers: Neither boronizing nor nitriding are coatings, but diffusion treatments. This means that both treatments are more permanent and can protect the material more efficiently. They can not peel or chip off, as some coatings are prone to do so.
Which metals are suitable for boronizing?
The boriding process can be applied to a wide range of materials, such as:
- Plain carbon steel
- Medium carbon steel
- Tool steel
- Alloy steels
- Cast Steels
- Structural steels