## 3 Results
### The Thickness of the Hardened Layer and the Surface Hardness after Boriding Steel Products
Metallographic studies show that steel 40 Cr typically has wide wedges, which are much thinner in steel 18 Cr2 Ni4 Mo. There are differences in the phase composition. On the diffraction pattern of bearing steel Cr15, in addition to borides FeB and Fe\({}_{2}\)B, there is a boride of chromium (Cr\({}_{2}\)B) and a special carbide Cr\({}_{7}\)C\({}_{3}\). The alloy steel 18 Cr2 Ni4 Mo comprises the borides of chromium CrB and Cr\({}_{2}\)B, borides of molybdenum MoB\({}_{2}\) and Mo\({}_{2}\)B, and a cementite phase. In high-speed steels (W18, W6 Mo5), the worsening of wedges borides is significantly reduced before their rounding (Figure 7). This fact is associated with the diffusion inhibition of boron alloying elements. These steels are characterized by a solid boride layer and separate rounded sections of borides under it. Layer-by-layer, X-ray phase analysis confirmed the presence of borides FeB, and Fe\({}_{2}\)B, borides of alloying elements Cr\({}_{2}\)B, CrB, Cr\({}_{3}\)B\({}_{4}\), Mo\({}_{2}\)B, Mo\({}_{2}\)B\({}_{5}\), MoB\({}_{2}\), W\({}_{2}\)B, and W\({}_{2}\)B\({}_{5}\), and carbides of Cr\({}_{7}\)C\({}_{3}\), B\({}_{4}\)C Fe\({}_{3}\)C, VC, and WC in the diffusion layer. According to experimental data, the dependence of the thickness of the boride length of boriding for different steels (Table 1) shows that the thickness of the boride layer for all steels increases with the duration of the process. The rate of growth is highly dependent on the composition of the steel. Figure 6: The diffraction pattern of the bearing steel Cr15 on the surface after boriding at a temperature of 850 \({}^{\circ}\)C for 2 h.  
Figure 7: The microstructures of the boride layers on steel high-speed tool steel W6 Mo5 (**a**) and high-speed tool steel W18 (**b**) after boriding at the temperature of 1000 \({}^{\circ}\)C for 2 h.  
The surface layer's hardness also depends on the steel composition. However, to a much lesser extent, the hardness of borides (FeB, Fe\({}_{2}\)B), which are the main phases of the surface layers in the carbon content and alloying elements, slightly depends on the steel composition. Microhardness confirms the presence of two borides FeB with the hardness of 20-23 GPa, and Fe\({}_{2}\)B--with the hardness of 15-18 GPa. Structural carbon steels [48] are characterized by a smooth microhardness distribution in the transition zone than in the tool. The surface hardness is in the range of 20-22 GPa for structural carbon steel. Additionally, the surface hardness is up to 21-23 GPa for cutting alloy steel. Thus, in order to simplify the technological process of hardening treatment of all steels (except high-speed steels), it is proposed to combine the boring operation with the hardening operation. For these, it is advisable to carry out boring at a temperature of 1000 \({}^{\circ}\)C after hardening. The duration of boring is selected under the requirements of the parts. The corresponding time should not be less than 30 min for structural steels, 45 min for carbon tool steel, and 120 min for high-alloyed steels. The evaluation of abrasive wear resistance of steels without CHT and after nitriding and boring on the developed technologies showed the samples' linear wear. The durability \(I_{uv}\) of wear resistance was evaluated using the wear rate \(I_{r}\) (\(I_{uv}=1/I_{r}\), where \(I_{r}\)--the ratio of the wear \(I\) along with the path \(L\), which has been fraying \(I_{r}=I/L\)). Studies have shown the linear dependence of the wear from the friction path for all steels for both nitridded and borated conditions. After boring, wear is significantly less than it is following nitriding [49; 50]. On the probationary path of 200 m, the amount of wear after boring 2.1-3.6 times (depending on steel grades) is less than that following nitriding. This fact is primarily due to the significantly higher hardness of the boride layers.