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Boronizing or boriding is defined as a thermochemical surface treatment process of diffusion and chemical reaction of boron atoms into the substrate at elevated temperatures ranging between 800 to 1000◦ C for several hours [1–3]. Thus, boron atoms are diffused into a metal substrate and form one or more hard boride layers on the metal surface. Boriding procedure is dependent on boriding agent, boriding type, boriding temperature, and boriding time. Boriding temperature is the biggest factor, which affects the cost of the process and choice of the substance to be borided. Elevated temperatures may be detrimental to the mechanical properties of the substrate. Boron compounds are used in fertilizer, pharmaceutical, cleaning, nuclear, steel, ceramics, and space industry [4–6]. Boron is one of many commercially important minerals and compounds. It is used as slag builder, alloy element, and surface hardener. Many borides and boron carbides are formed in steels depending on the alloying element. Borides are FeB and Fe2B compounds. High carbon steel and cast iron boron carbide phases are formed. By boriding to other surface hardening processes one obtains very hard surface (about 2100 HV), low coefficient of friction resistance to some acid, base, and high temperature oxidation [7].

In the process of diffusing boron to the steel surface, single-phase iron boride (Fe2B) layer is obtained. A large effect can be achieved with boron atoms between austenite grain boundaries. The boronizing treatment can be realised in a medium together with other additions in solid, liquid, or gaseous form. Recently plasma boron and ion implantation boron …