Fe2B Boride Research Articles

Boriding Effect on the Hardness of AISI 1020, AISI 1060, AISI 4140 Steels and Application of Artificial Neural Network for Prediction of Borided Layer

Artificial neural network approach was used to predict the thicknesses of total (FeB+Fe2B), FeB and Fe2B borides layers of AISI 1020, AISI 1060, and AISI 4140 steels. Boronizing heat treatment was conducted in a solid medium comprising of EKabor®2 powders at 840–960 ˚C at 40 ˚C intervals for 2, 4, 6, and 8 hours. Optical microscope analysis of the borided layer revealed the saw-tooth (columnar) and planar morphology. The depth of the total (FeB+Fe2B), FeB and Fe2B boride layers was accurately predicted. For total boride layers generated by the artificial neural network model, the average error varied between 0.04 and 7.64 µm. Micro hardness values increased by 423% in AISI 1020, 336% in AISI 1060, and 411% in AISI 41040 after the boronizing process.

Surface modification of die steels by liquid boriding

The research investigates the effect of liquid boriding on the microstructure, composition and microhardness of the surface layer on 5KhNM and 3Kh2V8F die steels. Boriding was carried out for 8 hours at 850 and 1000 °С in a melt based on sodium tetraborate and sodium salts. After high-temperature exposure during the boriding process, the samples were quenched in oil and tempered. Next, the samples were subjected to metallographic, X-ray spectral, X-ray diffraction and durometric analyses. As a result of processing, boride diffusion layers were obtained on the surface of 5KhNM and 3Kh2V8F steels up to 100 and 130 μm thick, respectively. It has been established that iron borides Fe2B and FeB are formed on the surface of both steels. In addition, chromium boride CrB is additionally formed on the surface of 5KhNM steel, increasing the maximum microhardness of the layer to 2130 HV. The maximum microhardness of 3Kh2V8F steel reaches 1709 HV due to the formation of borides and carbides in the layer. A study of the surface topography after boriding showed that the roughness parameter Ra of 5KhNM steel increased by 1.87 times, and of 3Kh2V8F steel by 1.78 times compared to the initial state.

Enriching 2D transition metal borides via MB XMenes (M = Fe, Co, Ir): Strong correlation and magnetism.

Recently, two-dimensional (2D) FeSe-like anti-MXenes (or XMenes), composed of late d-block transition metal M and p-block nonmetal X elements, have been both experimentally and theoretically investigated. Here, we select three 2D borides FeB, CoB and IrB for a deeper investigation by including strong correlation effects, as a fertile ground for understanding and applications. Using a combination of Hubbard corrected first-principles calculations and Monte Carlo simulations, FeB and CoB are found to be ferro- and anti-ferro magnetic, contrasting with the non-magnetic nature of IrB. The metallic FeB XMene monolayer, superior to most of the MXenes or MBenes, exhibits robust ferromagnetism, driven by intertwined direct-exchange and super-exchange interactions between adjacent Fe atoms. The predicted Curie temperature (TC) of the FeB monolayer via the Heisenberg model reaches an impressive 425 K, with the easy-axis oriented out-of-plane and high magnetic anisotropic energy (MAE). The asymmetry in the spin-resolved transmission spectrum induces a thermal spin current, providing an opportunity for spin filtration. This novel 2D FeB material is expected to hold great promise as an information storage medium and find applications in emerging spintronic devices.

Effect of boriding on tribocorrosion behaviour of HSLA offshore mooring chain steel

This study explores the transformative potential of boriding to enhance the tribocorrosion resistance of mooring chain steel for offshore environments. The boride layers formed at various temperatures (800 °C, 900 °C, and 1000 °C) for 1 h, revealing high hardness (17–21 GPa). X-ray diffraction confirmed dual-phase FeB and Fe2B borides, contributing to superior mechanical properties. Energy-dispersive X-ray spectroscopy showed clear phase boundaries. Potentiodynamic data demonstrated improved corrosion and tribocorrosion resistance, particularly at higher boriding temperatures. Mechanical effects played a pivotal role in tribocorrosion behaviour, emphasizing the need to optimize boriding process temperatures. Electrochemical impedance spectroscopy highlights the 900 °C-1 h sample as offering excellent corrosion resistance. This study underscores boriding's potential to enhance the tribocorrosion resistance of offshore mooring chain steel.

Experimental and computational analysis of stacking fault energy in B-doped Fe50−XMn30Co10Cr10BX multi-principal elements alloys

The effect of boron doping in Fe50−XMn30Co10Cr10BX multi-component alloys on the resulting stacking fault energy has been experimentally and computationally assessed to understand the alloys' deformation mechanisms from structural and thermodynamic perspectives. Firstly, the fcc and hcp phases were identified together with stacking faults along their (110) planes using high-resolution transmission electron microscopy. At the same time, they were theoretically predicted through thermodynamic CALPHAD and ab initio calculations. The average stacking fault energy for the boron-free alloy was 23.9 ± 2.4 mJ/m2, suggesting that the deformation mechanisms relate to dislocation slip and deformation twinning. The average stacking fault energy for the highest boron content (5.4 at%) was 50.1 ± 14.1 mJ/m2, indicating dislocation glide as the possible deformation mechanism. The boron content in the solid solution was modelled. The modelling suggested that the presence of Cr-B, Mn-B and Fe-B bonds points towards forming (Cr,Fe)2B borides, which was experimentally confirmed. The borides, fcc phase stability, and the boron in solid solution contribute to increased stacking fault energy, preventing the motion of Shockley partial dislocations and influencing the ɛ-hcp martensitic transformation.

Структура и свойства низкоуглеродистой стали после плазменной наплавки борсодержащей обмазки

Introduction. One of the effective thermochemical methods for increasing the hardness of steel is boronizing by diffusion of boron atoms into the steel surface at high temperatures. As a result of boronizing, coatings are formed on the steel surface, consisting of columnar crystals of FeB and Fe2B. The volume fraction of phases and the thickness of the coatings depend on the heating temperature and the chemical composition of the base material and the saturating medium. The main disadvantage of these boronized layers is its high brittleness. Boronizing by plasma heating is one of the alternatives to the diffusion boronizing process to minimize the brittleness of the boronized layer. The purpose of the work: to form boride coatings on low-carbon steel using plasma-jet hard-facing. The research methods are: determination of the content of chemical elements using an electron probe micro-analyzer, metallographic studies, analysis of the phase composition of the boronized layer, as well as measurement of the microhardness of the coating after plasma-jet hard-facing. In this work boronized layers obtained on low-carbon steel 20 by plasma-jet hard-facing of a boron-containing coating are studied. Powdered amorphous boron was used as an alloying element. The parameter varied during plasma-jet hard-facing process is the current strength (120 A, 140 A and 160 A). Results and discussions. Based on the studies performed, it is found that it is possible to form boronized layers on the steel surface using plasma-jet hard-facing method. It is noted that the surface layer of the coating of the 1st and 2nd specimens after plasma-jet hard-facing has a heterogeneous structure, consisting of rows of different zones. The first zone has a hypereutectic structure, which consists of primary borides FeB and Fe2B, located in the eutectic, consisting of Fe2B and α-Fe. The second zone above the boundary with the base metal is represented by eutectic colonies composed of Fe2B and α-Fe. The third specimen is characterized by a hypoeutectic structure consisting of boride eutectic and primary dendrites of the α-solid solution of boron in iron. The maximum hardness is fixed on the surface of the first specimen and is 1,575 HV. The depth of the hardened layer increases with increasing current, but the hardness value and boron content decrease after treatment. The slight hardness gradient observed over the depth of the coating, as well as the gradual decrease in hardness due to the presence of the transition zone, are considered favorable for good adhesion of the boronized layer to the surface of the base material.

MORPHOLOGY AND PHASE COMPOSITION OF DIFFUSION BORIDE LAYER BASED ON METALLOGRAPHIC ANALYSIS OF STEEL 45

Chemical-thermal treatment in general and borating in particular are highly effective ways to increase the service life of working bodies and machine parts, as well as tools. At the same time, it is necessary to select possible grades of steels, which are preferably subjected to boriding, depending on the goal. To solve practical problems in order to control the quality of a boride diffusion coating, there is a need to determine the strength and morphological characteristics of the boride layer and its phase composition. Since the high- boride FeB phase has low performance characteristics (high brittleness, creates tensile stresses on the surface, leading to cracking and spalling in the boride layer), in most cases the content of the FeB phase in the coating is limited to an upper limit of no more than 10–15 % of the thickness of the boride layer. Determination of the phase composition of boride layers is preferably carried out by electron microscopy methods, however, under production conditions, this is a laborious task. One of the options for analyzing the structure and morphology of the results obtained is the visualization of the phase composition of boride diffusion layers using "color etching'' with the possibility of assessing the structural-phase state using optical microscopy. It is shown that the electrolytic etching method proposed in this work in a saturated aqueous solution of alkaline sodium picrate makes it possible to obtain high-contrast images of the microstructure of the boride layer, which can subsequently be automatically processed in modern software systems for metallographic analysis in order to qualitative and quantitative assessment of the structural-phase state. Compared to the chemical methods of "color etching", the electrochemical etching method does not require highly skilled personnel and can be used in a production laboratory.

Effects of Mo alloying on the microstructure and wear resistance of Fe–B surfacing alloys

The effect of Mo addition on microstructure, impact property, and wear resistance of high boron Fe-4.5 wt% B surfacing alloy, which was developed by the three-arc double-wire welding method was investigated in this work. The phase structure and microstructure of the surfacing alloy were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and Electron Backscattered Diffraction (EBSD). Besides, a two-body abrasive wear test and impact fracture test was carried out to study the wear behavior and fracture mechanism of the surfacing alloy. The results show, hypereutectic Fe-4.5 wt% B surfacing alloys with different Mo additions are mainly composed of primary (Fe, Mo)2B boride, eutectic matrix, and FeMo2B2. With the increase of Mo content in Fe-4.5 wt% B surfacing alloy, the continuous growth of the eutectic structure is blocked, which can inhibit the formation and expansion of cracks in the surfacing layer. With the increase of Mo, the wear resistance of Fe-4.5 wt% B alloy increases from 16.70 g-1 to 22.72 g-1. In the impact fracture experiment, Fe-4.5 wt% B surfacing alloy has high brittleness, the primary Fe2B is a transgranular fracture, and the interface between primary Fe2B boride and eutectic structure is an intergranular fracture. With the addition of Mo, the fracture mechanism of the surfacing alloy changes from transgranular fracture to transgranular fracture + ductile fracture, which reduces the fragmentation and spalling during the wear process, thereby improving its wear resistance.

Selective Laser Melting of (Fe-Si-B)/Cu Composite: Structure and Magnetic Properties Study

A mixture of original 1CP powder and 10 wt.% of pure Cu-powder was prepared and 1CP-Cu composite samples were obtained by selective laser melting using different process parameters. Comparison of pure 1CP and composite samples showed that addition of Cu halved the porosity percentage of the obtained material. Distribution of Cu-phase in 1CP-matrix can be recognized as uniform in all the samples. X-ray diffraction of samples showed the presence of α-Fe solid solution, iron boride Fe2B, and crystal Cu. Scanning electron microscopy analysis also allowed to discover ordered solid solution Fe3Si in samples microstructure. Differential scanning calorimetry data showed that composite sample contains amorphous phase as opposed to pure 1CP sample manufactured using the same process parameters. Magnetic properties of samples were studied, and it was found that addition of 10 wt.% of Cu allowed to reduce magnetic field energy losses by approximately four times.

Investigation of the structure and properties of surface composite layers on multi-alloyed steels

In this work were studied the structures and properties of surface composite layers obtained by chemical-thermal treatment and combined chemical-thermal treatment, combining liquid-free electrolysis-free boriding with gas nitriding. The properties of surface composite layers on steels with different alloys are analyzed depending on various parameters of chemical-thermal treatment. The study showed that, during boriding, phases of iron borides FeB, Fe2B are formed on the surface of the samples, and their volume ratio strongly depends on the degree of steel alloying. A strong effect of carbon on the morphology of surface layers was revealed. Finely dispersed strengthening particles were found in the borated layers on the VKS-5 steel, large superhard particles on the Ch12MF steel near the borated layers. The study of the microstructure of the composite layers showed that during gas nitriding, a layer 80 μm in size is obtained, which penetrates deep into the borated layer. The study of the properties of surface layers showed that carbon has the greatest influence on the formation of borated layers. The resulting composite layers are characterized by reduced microbrittleness and increased corrosion resistance.

Modeling of the phase-structural state in a hybrid multicomponent alloy with a high boron content

The present work is focused on analyzing the thermodynamically equilibrium path of structure formation in a multi-component Fe-W-Mo-Cr-Ti-Mn-Si alloy of tribotechnical purpose, containing 0.72 wt. % C and 2.75 wt. % B is analyzed. Computer simulation of the crystallization process was performed using the program “Thermo-Calc Software”. It was found that the alloy belongs to the hyper-eutectic compositions, since its crystallization begins at 1472 oC with the formation of primary boride WB and carbide TiC. After a series of subsequent eutectic reactions (in the range of 1126-923 oC) and solid-phase transformations, a set of equilibrium phases is formed in the alloy, which at room temperature consists of borides WB, MoV, Fe2B, Cr4B, Mn4B, carbides TiC, M7C3, and ferrite. The total volume fraction of borides and carbides is 45.05 vol. %. A comparison of the obtained data with the results of the study of the manufactured alloy showed that the simulation with “Thermo-Calc Software” provides satisfactory adequacy in predicting the structure in the alloys of the selected alloying system.

Corrosion behavior of novel Fe–Cr–B alloys containing high Cr content in molten aluminum

AbstractMaterials applied in the aluminum processing industry commonly suffer harsh corrosion on account of the high aggressivity of molten aluminum. Fe–Cr–B alloys have shown outstanding corrosion resistance to molten aluminum due to the presence of Cr‐rich borides displaying high stability. Accordingly, three Fe–Cr–B alloys with high Cr contents (20.6, 28.7, and 36.6 wt%) were fabricated in this study. As the Cr content increased from 20.6 to 36.6 wt%, the (Cr,Fe)2B borides ultimately transformed into Cr2B borides. A corrosion test was carried out in molten aluminum at three temperatures (700°C, 750°C, and 800°C) for 4 h and the volume losses of the studied alloys were measured to estimate their corrosion resistance. The Fe–Cr–B alloy with 28.73 wt% Cr exhibited the finest corrosion resistance among the three studied Fe–Cr–B alloys on account of enhancing the corrosion resistance of the Fe matrix by solution mechanism as well as maintaining the generation of periodical layered structures in its corrosion interface. In addition, as the test temperature expanded, the volume loss of Fe–Cr–B alloys stepped up slowly, whereas that of H13 tended to increase drastically.

Structure, Microstructure, Hyperfine, Mechanical and Magnetic Behavior of Selective Laser Melted Fe92.4Si3.1B4.5 Alloy

A disordered ε-FeSi crystalline structure was produced by selective laser melting in Fe92.4Si3.1B4.5 powder alloys fabricated with different laser powers at a laser scanning speed of 0.4 m/s. The phase formation, microstructure, roughness, microhardness, and hyperfine and magnetic properties were studied using X-ray diffraction, scanning electron microscopy, atomic force microscopy, a profilometer, a microdurometer, transmission 57Fe Mössbauer spectrometry and vibrating sample magnetometry. The aim of this work was therefore to study the effect of laser power on the phase formation, microstructure, morphology, and mechanical, hyperfine and magnetic properties. The XRD patterns revealed the coexistence of a bcc α-Fe0.95Si0.05, a tetragonal Fe2B boride phase and a disordered ε-FeSi type structure. The existence of the disorder was confirmed by the presence of different FeSi environments observed in the Mössbauer spectra. The Fe2B boride contained about 51–54% of Fe atoms. The porosity and roughness decreased whereas laser power increased. The sample produced with a laser power of 90 W had a smooth and dense surface, high microhardness (~1843 Hv) and soft magnetic properties (saturation magnetization Ms = 200 emu/g and coercivity Hc = 79 Oe).

Interaction of Carbon, Titanium, and Boron in Micro-Alloy Steels and Its Effect on Hot Ductility

Varying contents of carbon, titanium and boron were used in the base steel composition of 0.30 wt% Si, 2.0 wt% Mn, 0.006 wt% S, 0.03 wt% Nb, and 30–35 ppm N. Hot ductility tests were performed with Gleeble-3800, after the steel sample was in-situ melted, solidified, and cooled to the test temperature. Investigation was completed with thermodynamic and kinetic simulations. The best results were obtained for steels containing 58–100 ppm B and 35 ppm Ti. They showed very good hot ductility of 80–50% RA within the temperature range between 1250 °C and 800 °C. It was shown that titanium and boron were effective in improving the hot ductility. Titanium protected boron from binding into BN and was low enough to prevent excessive (Ti,Nb) carbonitride precipitation, which both could decrease hot ductility. Boron that precipitated along austenite grain boundaries as iron boride Fe2B was very beneficial for the hot ductility of steel.

Влияние борирования и алитирования на структуру и микротвердость низкоуглеродистых сталей

Introduction. Boriding and aluminizing are among the effective methods for improving the performance properties (corrosion resistance, heat resistance and wear resistance) of machine parts and tools. Solid-phase methods of carrying out techniques of thermochemical treatment (TCT) require long-term exposure at elevated temperatures, which negatively affects the structure and properties of the base material. From these positions, the selection of reasonable temperature-time parameters of solid-phase boriding and aluminizing processes is an urgent task. The purpose of this work is to assess the effect of low-temperature boriding and aluminizing processes on the structure and microhardness of diffusion layers on the surface of low-carbon steels. The paper considers two grades of steels with a carbon content of up to 0.4%: low-carbon steel St3 and alloy steel 3Cr2W8V. The use of the second steel is due to the need to identify the effect of alloying elements in steel on the thickness of diffusion layers and its composition. Powder mixtures based on boron carbide and aluminum carbide are selected as sources of boron and aluminum. Results and discussions. It is found at a process temperature of 900 °C and holding for 2 hours after boriding, iron borides are formed on the surface of both steels. At the same time, two borides FeB and Fe2B are detected on St3 steel by X-ray phase analysis (XRD), and only the Fe2B phase is detected on 3Cr2W8V steel. After aluminizing, aluminum-containing phases such as Al5Fe2, Na3AlF6 and Al2O3 are formed in both steels. The thickness of the resulting diffusion layer on St3 after boriding is 35 μm, after aluminizing – 65 μm. The thickness of the diffusion layer on 3Cr2W8V steel is equal to 15 μm after boriding and 50 μm after aluminizing, which is significantly less than on carbon steel and is obviously due to the effect of alloying elements. It is established that TCT leads to a significant increase in the microhardness of the samples surface. Thus, the maximum microhardness of St3 steel increased to 2,000 HV, and the maximum microhardness of 3Cr2W8V steel increased to 1,700 HV after boriding. The microhardness after aluminizing is comparable for both steels and is equal to 1,000-1,100 HV. Elemental analysis of the upper sections of the diffusion layers shows that the content of boron (7-9%) and aluminum (50-53%) corresponds to the detected XRD iron borides and aluminides. In all cases, there is a gradual decrease in the diffusing elements in the direction from the surface to the base.

Features of formation of diffusion zone obtained on steel 20 by boriding in induction furnace

The article presents data on studies of iron borides synthesis during induction heating to 1000 °C for 5 min of steel 20 samples with a coating from a charge containing Fe – H3BO3. Content of boric acid in the charge varied from 25 to 75 % wt. Charge in the experiments could be diluted with a solution of liquid glass in water with addition of small amount of ammonium hydroxide and coal. Study of the surface layer microhardness showed that during saturation of the surface layer of carbon steel 20 with boron, a macroscopically extensive diffusion zone 900 – 1000 μm in size is formed, in which the boride content gradually decreases when moving deeper into the matrix. Such a size of the diffusion zone indicates an anomalously high mass transfer during boriding of steel 20. Indeed, the calculated diffusion coefficient during boriding under induction conditions (about 1.35·10–9 m2/s) is two orders of magnitude higher than the diffusion coefficient in the classical boriding. X-ray studies showed that, under the considered conditions, Fe2B and FeB borides are synthesized, and a solid solution of boron in α­iron is also formed. An analysis of phase composition of the diffusion zone structural components indicates that, from the surface to the matrix, formation of boride phases occurs in the following sequence: FeB → Fe2B → (α­phase + B) → base metal. Microstructure of the diffusion zone consists of more or less pronounced layers consisting of FeB and Fe2B boride phases. On the whole, especially deep-ying regions of the diffusion zone are a composite material consisting of plastic α-phase and iron boride crystals. Crystals in FeB and Fe2B in the layer are oriented mainly perpendicular to the diffusion front. Perhaps, this is due to the rapid predominant growth of the boride phase under conditions of high diffusion mobility of boron atoms in one direction and hindered in others.

Thermal-oxidation behavior of single-phase boride layers produced on pure iron

The influence of the oxidation temperature on the single-phase borided layer was investigated. Oxidation at a temperature range 1073–1273 K resulted in formation of a two-zone oxidized layer: outer zone contained iron oxides and inner zone consisted of iron borates. It was found the intensive dissolution of Fe2B phase started at the temperature of 1173 K and was the reason for appearance of the boron-rich FeBO3 phase. The increase in temperature to 1273 K resulted in the complete dissolution of borided layer. No negative influence of oxidation at 1073 K on nanomechanical properties of iron boride Fe2B was observed.

Оценка структурно-фазового и напряженного состояния диффузионных боридных слоев, полученных химико-термической обработкой на поверхности штамповой стали 3Х2В8Ф

Introduction. Control and management of technological residual stresses (TRS) are among the most critical mechanical engineering technology tasks. Boriding can provide high physical and mechanical properties of machine parts and tools with minimal impact on the stress state in the surface layers. The purpose of this work is to determine the temperature modes of diffusion boriding, contributing to a favorable distribution of TRS in the surface layer of die steel 3Kh2V8F. The paper considers the results of studies on the TRS determination by the experimental method on the UDION-2 installation in diffusion layers on the studied steel surface. Boriding was carried out in containers with a powder mixture of boron carbide and sodium fluoride as an activator at a temperature of 950 °C and 1050 °C for 2 hours. The obtained samples of steels with a diffusion layer were examined using an optical microscope and a scanning electron microscope (SEM); determined the layers' microhardness, elemental, and phase composition. The experiments resulted in the following findings: as the boriding temperature rose from 950 °C to 1050 °C, the diffusion layer's thickness increased from 20 to 105 μm. The low-temperature mode of thermal-chemical treatment (TCT) led to the formation of iron boride Fe2B with a maximum boron content of 6 % and a microhardness up to 1250 HV. A high-temperature mode resulted in FeB formation with a top boron content of 11 % and a microhardness up to 1880 HV. Results and Discussions. It is found that boriding at 950 °C led to a more favorable distribution of compression TRS in the diffusion layer. However, significant TRS fluctuations in the diffusion layer and the adjacent (transitional) zone could affect the operational properties after TCT at a given temperature. An increase in the TCT temperature led to tensile TRS's appearance in the layer's upper zone at a depth of up to 50 μm from the surface. Despite tensile stresses on the diffusion layer surface after high-temperature TCT, the distribution of TCT is smoother than low-temperature boriding.

Laser Surface Alloying of Austenitic 316L Steel with Boron and Some Metallic Elements: Properties.

Austenitic 316L stainless steel is known for its good resistance to corrosion and oxidation. However, under conditions of appreciable mechanical wear, this steel had to demonstrate suitable wear protection. In this study, laser surface alloying with boron and some metallic elements was used in order to improve the hardness and wear behavior of this material. The microstructure was described in the previous paper in detail. The microhardness was measured using Vickers method. The “block-on-ring” technique was used in order to evaluate the wear resistance of laser-alloyed layers, whereas, the potentiodynamic method was applied to evaluate their corrosion behavior. The produced laser-alloyed layers consisted of hard ceramic phases (Fe2B, Cr2B, Ni2B or Ni3B borides) in a soft austenitic matrix. The significant increase in hardness and wear resistance was observed in the case of all the laser-alloyed layers in comparison to the untreated 316L steel. The predominant abrasive wear was accompanied by adhesive and oxidative wear evidenced by shallow grooves, adhesion craters and the presence of oxides. The corrosion resistance of laser-alloyed layers was not considerably diminished. The laser-alloyed layer with boron and nickel was the best in this regard, obtaining nearly the same corrosion behavior as the untreated 316L steel.

Mechanical Characterization and Micro-Wear of FeB-Fe<sub>2</sub>B Layers on Boriding AISI D2 and AISI 4340 Steels

The mechanical behavior and wear of the different hardened phases with bore-induced changes in AISI 4340 and AISI D2 steels were investigated. The hardness and modulus of elasticity were measured by nanoindentation and the values obtained for the layers in AISI D2 steel were 18 GPa and 325 GPa in the Fe2B boride phase, and 20 GPa and 360 GPa in the FeB boride phase, respectively. The AISI 4340 steel presented mainly the Fe2B phase. It was then possible to analyze the coefficient of friction obtained in the Fe2B phase of the steel AISI 4340 presented a range of 0.04 to 0.06. The AISI D2 steel presents two different phases in the boride layer being the coefficient of friction higher for the test in the FeB phase than for Fe2B, and the values vary from 0.065 to 0.075. These parameters were obtained with micro-wear tests. No adhesion failures were observed after the sliding tests in the interface of the two different boride layers. Cracks in the FeB phase after the sliding test were much more frequent.