BOROCOAT®

The materials are treated in a temperature range from 750 to 950 °C. Of fundamental importance here is optimum heat distribution in the furnaces used in order to treat all parts of a batch uniformly. During the boronizing process, complex intermetallic compounds are formed between the elements iron, boron, chromium, nickel, vanadium, etc. The resulting borides form a hard surface layer consisting of Fe₂B and other compounds.

Due to its crystalline structure, the boride layer exhibits excellent anchorage with the base material. For treatment, the boron donor can be in powder, paste or granular form. Individual, large parts, set material and bulk material can be refined.

With its EKABOR® products, BorTec provides suitable boronizing agents for all requirements. The boriding process is particularly suitable for unalloyed and low-alloyed steel grades. As the proportion of alloying elements increases, the diffusion rate and thus the thickness of the achievable boride layer decreases. At the same time, alloying elements such as nickel and chromium contribute to an increase in hardness and wear resistance.

The range of materials which can be boronized is diverse and extends from cast iron, cast steel, most steel grades to NICKEL BASED ALLOYS and special materials such as Stellite®. Materials containing silicon and aluminum represent a limitation. Steels with correspondingly high contents of the elements mentioned can impair the boriding result.

The main difference between boronizing and boron-alloyed steel is the amount of boron introduced into the material. In boronizing, an agent (e.g. EKABOR®) is applied to the surface layer to change the outer area of the material. This means that the core remains unaffected by the boron. Even a small amount of boron, however, can significantly improve hardenability; concentrations of about 0.0015% to 0.0030% are accepted as peak values, but may vary depending on the hardening technique.
Boron alloyed steel, on the other hand, contains boron throughout its volume. This means that the core also contains boron. Between alloys, the amount of boron added to the material can vary depending on what hardening properties are required.

Boron alloyed steel typically has poorer forging properties and ductility than steels that do not contain boron. When it comes to a decision between boronized steel and boron-alloyed steel, there is no universal answer. It depends on the use and application as to which material is best. While both materials offer some hardness, boron steel tends to be less ductile due to its through hardening. Boronized steel retains its soft core (assuming the parent material counts as such) and exhibits greater toughness. When it comes to already fabricated components, boronizing is the better choice for wear protection.