Borided AISI Research Articles

Tribological behavior of borided AISI 1018 steel under linear reciprocating sliding conditions

In this study, the wear behavior of AISI 1018 borided steel is characterized. The boriding thermochemical treatment was carried out at 1273K for 6h, and different thicknesses of the boriding agent surrounding the samples were examined. The layer structure was composed of FeB and Fe2B layers.The tribological properties at the surface of borided and unborided steel were evaluated employing the ball-on-flat method with sliding reciprocating wear tests, using an Al2O3 ball as the counterpart. The applied load and the sliding speed remained constant at 5N and 5mm/s, respectively, with sliding distances of 81m, 108m and 135m.The coefficients of friction (CoFs) on the boride layers from the sliding reciprocating wear tests for dry and lubricated conditions were evaluated. The CoFs are independent of the boriding potential expressed as the powder thickness. Surface wear for longer sliding distances in lubricated conditions was neglected; there was no difference between the wear track and the original surface roughness in the profilometer results. The wear scar diameter and the worn surfaces of borided and unborided steels in both experimental conditions were characterized by SEM to understand the wear mechanisms.

Preiskava adhezije in obrabnih lastnosti boriranega jekla AISI H10

Preiskava adhezije in obrabnih lastnosti boriranega jekla AISI H10

Investigation of Adhesion and Tribological Behavior of Borided AISI 310 Stainless Steel

In the present study, the effects of the boriding process on adhesion and tribological properties of AISI 310 steel were investigated. Boriding was performed in a solid medium consisting of Ekabor-II powders at 1123 and 1323K for 2 and 6 h. The boride layer was characterized by optical microscopy, the X-ray diffraction technique and the micro-Vickers hardness tester. The X-ray diffraction analysis of the boride layers on the surface of the steels revealed the existence of FexBy, CrxBy and NixBy compounds. Depending on the chemical composition of substrates, the boride layer thickness on the surface of the AISI 310 steel was found to be 56.74 μm. The hardness of the boride compounds formed on the surface of the AISI 310 steel ranged from 1658 to 2284 HV0,1, whereas the Vickers hardness value of the untreated steel AISI 310 was 276 HV0,1. The wear tests were carried out in a ball-disc arrangement under a dry friction condition at room temperature with an applied load of 10N and with a sliding speed of 0.3 m/s, at a sliding distance of 1000m. The wear surfaces of the steel were analyzed using an SEM microscopy and X-ray energy dispersive spectroscopy EDS. It was observed that the wear rate of unborided and borided AISI 310 steel ranged from 4.57 to 71.42 mm3/Nm.

Kinetika difuzije in karakterizacija boriranega jekla AISI H10

Kinetika difuzije in karakterizacija boriranega jekla AISI H10

Študij kinetike in karakterizacija boriranega jekla AISI 4140

Študij kinetike in karakterizacija boriranega jekla AISI 4140

Diffusion kinetics and characterization of borided AISI D6 steel

In this study, the case properties and diffusion kinetics of AISI D6 steel borided in Ekabor-II powder were investigated by conducting a series of experiments at temperatures of 1123, 1223 and 1323 K for 2, 4 and 8 h. The boride layer was characterized by optical microscopy, X-ray diffraction technique and microVickers hardness tester. X-ray diffraction analysis of boride layers on the surface of the steels revealed the existence of FeB, Fe2B, CrB and Cr2B compounds. Depending on the chemical composition of substrates and boriding time, the boride layer thickness on the surface of the steel ranged from 13.54 μm and 164.42 μm. The hardness of the boride compounds formed on the surface of the steels ranged from 1672 to 2118 HV0.05, whereas Vickers hardness values of the untreated the steels was 584 HV0.05. The activation energies (Q) of the borided steel were 180.359 kJ/mol. The growth kinetics of the boride layers forming on the AISI D6 steel and the thickness of boride layers were also investigated.

Investigation of diffusion kinetics of borided AISI P20 steel in micro-wave furnace

In present study, kinetics of borides formed on AISI P20 steel has been investigated by boronizing treatment which was carried out in Ekabor-II powders at the process temperatures of 1123, 1173 and 1223 K for 2, 4 and 6 h in both micro-wave (M.F) and conventional atmospheric furnace (C.F). The properties of boride layer were evaluated by optical microscopy, X-ray diffraction and micro-Vickers hardness tester. The growth kinetics of the boride layers forming on the AISI P20 steel and thickness of boride layer were computed. The present phases in boride layers of borided AISI P20 steel were FeB, Fe2B, CrB and MnB respectively.The thickness of Boride layer formed on the surface of AISI P20 steel ranged from 26 to 143 μm in conventional furnace and ranged from 33 to 158 μm in microwave furnace with varying boriding temperature and time. Depending on temperature and layer thickness, the activation energies of boron for AISI P20 were determined to be 256.485 kJ/mol in conventional furnace and 213.935 kJ/mol at microwave furnace.

Effect of Precarburization on Growth Kinetics and Mechanical Properties of Borided Low-Carbon Steel

Boriding is a thermochemical process employed widely for increasing the resistance of ferrous materials to wear and corrosion. In this work, the influence of precarburization on microstructure, boride layer thickness, microhardness, growth kinetics, and mechanical properties of untreated and borocarburized AISI 1015 steel is studied. The thickness of boride layer ranges from 205.9 to 215.9 µm for borocarburized specimens to a maximum of 247.7 µm for borided AISI 1015 steel. The carbon content in the case improves the microstructure by the formation of single-phase iron boride mainly on the surface. Boride layer thickness decreases with increase in carbon content of the case. Activation energy for the borided AISI 1015 steel is 119.22 KJ/mol. The activation energies are 174.4 and 194.7 KJ/mol for borocarburized AISI 1015 steel having 0.30% C and 0.45% C, respectively. The activation energy increases with increase in carbon content due to precarburization. Empirical relations have been developed to predict boride layer thickness and are well correlated with experimental values for the process temperature and time. Tensile strength ranges from 421 to 599 N/mm2. Impact strength of borided specimens varies between 386.7 and 493.3 N-m while for borocarburized specimens it ranges between 103.7 N-m and 183.3 N-m. Fracture behavior of borided and borocarburized specimens under tensile and impact tests has been analyzed.

Mechanical Properties and Kinetics of Borided AISI M50 Bearing Steel

The present study reports on mechanical properties and kinetics of borided AISI M50 steel. AISI M50 steel is widely used for critical aircraft engine bearings operating at elevated temperatures with its combination of good hot hardness and excellent rolling contact fatigue strength. AISI M50 is also intermediate high-speed steel which make it suitable for using as woodworking tools and hacksaw blades. Despite its wide range of use, there is almost no published research on the boronizing of AISI M50 steel in the literatures. Boronizing thermochemical treatment was carried out in a solid medium consisting of EKabor-I powders at 850, 950, and 1,050 °C for 2, 4, 6, and 8 h, respectively. The presence of borides FeB and Fe2B on the steel substrate was confirmed via X-ray diffraction analyses and energy-dispersive X-ray spectroscopy. The results of this study indicated that the boride layer has a smooth and compact morphology, and its hardness was found to be in the range of 1,630–2,040 HV. Depending on process time and temperature, the thickness of boride layer ranged from 6 to 216μm. Layer-growth kinetics were analyzed by measuring the extent of penetration of the FeB and Fe2B sublayers as a function of boronizing time and temperature. The fracture toughness of borides ranged from 3.89 to 3.51 MPa m1/2. Moreover, an attempt was made to investigate the possibility of predicting the iso-thickness of boride layer variation and to establish an empirical relationship between process parameters and boride layer thickness.

Corrosion behavior and characterization of plasma nitrided and borided AISI M2 steel

This study investigates the corrosion behaviors of plasma nitrided (PN) and borided AISI M2 steels. The PN process was carried out in a dc-plasma system at a temperature of 923K for 6 h in a gas mixture of 80%N2-20%H2 under a constant pressure of 5 mbar. The boriding process was carried out in Ekabor-II powder at a temperature of 1223K for 6 h. X-ray diffraction analysis on the surface of the PN and borided steels revealed the presence of FeB, Fe2B, CrB, MoB, WB, FeN, Fe2N, Fe3N and Fe4N compounds. Corrosion surfaces of the samples were analyzed using a SEM microscopy and X-ray energy dispersive spectroscopy EDS. The corrosion resistance of PN and borided AISI M2 steel is higher compared with that of untreated AISI M2 steel. Corrosion resistances of the PN and borided AISI M2 steel increased the 4-6- fold.

Corrosion behavior of borided AISI 304 austenitic stainless steel

Purpose – The paper aims to clarify the effect of boriding on the corrosion behavior and mechanical properties of AISI 304 austenitic stainless steel. Design/methodology/approach – The commercially available steel was subjected to a boriding treatment with Ekabor III powders at temperatures of 1,223-1,273 K with boriding durations of 2-4 h. Microstructural characterization of the steel was carried out with optical microscopy, scanning electron microscopy and X-ray diffraction analyses. Static immersion corrosion tests were made using a 10 percent H2SO4 acid solution and salt spray tests were carried out in accord with the ASTM B-117 standard. Findings – Grain boundary precipitation of carbides was observed in the transition zone beneath the boride layers. The corrosion resistance of the steel against the acid solution increased to about seven times its untreated value with the boriding treatment. Research limitations/implications – The boride coating improved the corrosion resistance of the AISI 304 stainless steel against acidic media, but suffered from spalling in the salt spray test. Future work will focus on improving the adhesion between the coating and the substrate by changing the parameters for the boriding process. Practical implications – Pack boriding is a simple, environmentally friendly coating process and can be recommended for use in small and medium enterprises. The boride coatings deposited have potential in further improving the wear and corrosion resistance of stainless steels. Originality/value – The outcome of the research is of great importance for the industry using wear- and corrosion-resistant coatings.

Borlanmış AISI 5140 ve AISI 420 Çeliklerinin Difüzyon ve Adhezyon Davranışlarının İncelenmesi

Borlanmış AISI 5140 ve AISI 420 Çeliklerinin Difüzyon ve Adhezyon Davranışlarının İncelenmesi

The investigation of corrosion behavior of borided AISI 304 austenitic stainless steel with nanoboron powder

In this study, corrosion behavior and mechanical properties of AISI 304 austenitic stainless steel, which was borided with Nanoboron powder, was investigated. The commercially available steel was subjected to a boriding treatment with a size of 10–50 nm Nanoboron powders, at the temperatures of 1223 K to 1273 K with boriding durations of 2 to 4 h. Microstructure characterization of the steel was carried out with optical microscopy, scanning electron microscopy, microhardness and X-ray diffraction analyses. Corrosion tests were made by static immersion into a 10% H2SO4 acid solution and weight loss calculations as well as salt spray tests were carried out in accord with the ASTM B-117 standard. Boriding thermal treatment, increased the corrosion resistance of the steel against the acid solution, up to about 4.3 times while in the salt spray tests, weight loss corrosion resistance increased up to tier 2. However, anti-corrosion resistance decreased by 40%, its untreated value.

Investigation of Tribological Properties and Characterization of Borided AISI 420 and AISI 5120 Steels

In the present study, tribological and characterization properties of borides formed on AISI 420 martensitic stainless and AISI 5120 cementation steels have been investigated. The boride layer was characterized by optical microscopy, X-ray diffraction technique and the micro-Vickers hardness tester. X-ray diffraction analysis of boride layers on the surface of the steels revealed the existence of FeB, Fe2B and CrB compounds. The wear tests were carried out in a ball-disc arrangement under a dry friction condition at room temperature with an applied load of 10 N and with a sliding speed of 0.3 m/s at a sliding distance of 1,000 m. The wear surfaces of the steels were analyzed using a SEM microscopy and X-ray energy dispersive spectroscopy EDS. The results were compared with each other. It was observed that the friction coefficient of unborided and borided steels ranged from 0.42 to 0.63. The wear rate of the borided steels was found to be approximately five times lower the wear rate of the unborided steels.

Investigation of the diffusion kinetics of borided stainless steels

In this study, the kinetics of borides formed on AISI 420, AISI 304 and AISI 304L stainless steels was investigated. Boronizing treatment was carried out using Ekabor-II powders at the processing temperatures of 1123, 1173 and 1223 K for 2, 4 and 6 h. The phases of the boride layers of borided AISI 420, AISI 304 and AISI 304L stainless steels were FeB, Fe2B, CrB and NiB, respectively. The thickness of the boride layer formed on the borided steels ranged from 4.6 to 64 μm depending on the boriding temperature, boriding time and alloying elements of the stainless steels. Depending on the chemical composition, temperature and layer thickness, the activation energies of boron in AISI 420, AISI 304 and AISI 304L stainless steels were found to be 206.161, 234.641 and 222.818 kJ/mol, respectively. The kinetics of growth of the boride layers formed on the AISI 420, AISI 304 and AISI 304L stainless steels and the thickness of the boride layers were investigated.

Modelling of the Growth of Fe<sub>2</sub>B Layers in AISI 1018 Steel

In this work, a simulation of the growth kinetics of layers on AISI 1018 steel was done by means of a kinetic model. This model considers a solid diffusion of boron into a semi-infinite medium where the boron solubility in the Fe phase depends on the process temperature. An expression of the parabolic growth constant was then obtained through an application of the mass balance equation at the (/substrate) interface. The present model was validated by the experimental data available in the reference work (I. Campos-Silva et al: Kovove Mater. Vol.47 (2009), p.1-9). A good concordance was observed between the experimental parabolic growth constants and the predicted ones by the model for an upper limit of boron in the phase equal to 8.91 wt.% ( as a fitting parameter of the model). In addition, the generated weight gain was estimated at the surface of the borided AISI 1018 steel as a function of the upper limit of boron in the phase and the temperature.

Investigation of Boronizing Kinetics of AISI 51100 Steel

In this study, some mechanical properties of borided AISI 51100 steel with high C concentration were investigated. Boronizing heat treatment was carried out in solid medium consisting of Ekabor-II at 850, 900, and 950 °C for 2, 4, 6, and 8 h. Morphology and mechanical properties of boride layer, and the effect of chemical composition on properties and kinetics of borides were investigated. The results of this study indicated that the morphology of the boride layer has a saw-tooth nature, and its hardness is over 1500 HV. Depending on process time and temperature, the depth of boride layer ranged from 30 to 106 μm. Optical and SEM studies and XRD analysis revealed that borides formed on the surface of steel substrates have dominantly single Fe2B boride phase in addition to small amount of Cr2B.

Interfacial indentation test of FeB/Fe2B coatings

The present study uses interfacial indentation testing to estimate the adhesion of the FeB/Fe2B coating formed on the surface of borided AISI 316 steel. This technique creates and propagates a crack along the FeB/Fe2B interface and defines the apparent fracture toughness, which can then be related to the adhesion and mechanical support of the aforementioned interface. The boriding process was performed on the surface of AISI 316 steel by means of the powder-pack method at temperatures of 1123, 1173, 1223 and 1273K with 2, 4, 6, 8 and 10h for each temperature. The Young's modulus for each surface layer was obtained by Knoop microindentation at a constant indentation load. Vickers microindentation fracture technique was used to generate microcracks at the FeB/Fe2B interface with varying indentation loads. The applied load, Young's modulus, hardness, and lateral crack lengths generated from the corners of the indentations, along with the depth of the FeB layer, were used to determine the apparent fracture toughness and adhesion of the FeB/Fe2B interface. The apparent fracture toughness of the FeB/Fe2B interface varied between 3.56 and 4.45MPa m. Finally, the intensity of residual stress at the FeB/Fe2B interface was estimated as a function of the FeB layer thickness.

Kinetics of borided AISI M2 high speed steel

The present study reports on kinetics of borided AISI M2 high speed steel. Boronizing thermochemical treatment was carried out in a solid medium consisting of EKabor powders at 850 °C, 900 °C and 950 °C for 2, 4, 6 and 8 h, respectively. The presence of borides FeB and Fe 2B of steel substrate was confirmed by optical microscopy and scanning electron microscopy (SEM). The results of this study indicated that the morphology of the boride layer has a smooth and compact morphology, and its hardness was found to be in the range of 1600–1900 HV. Depending on process time and temperature the thickness of boride layer measured by a digital instrument attached to an optical microscope ranged from 3 to 141 μm. Layer-growth kinetics were analyzed by measuring the extent of penetration of the FeB and Fe 2B sublayers as a function of boronizing time and temperature. The fracture toughness of borides ranged from 4.80 to 5.21 MPa m 1/2. Moreover, an attempt was made to investigate the possibility of predicting the iso-thickness of boride layer variation and to establish an empirical relationship between process parameters and boride layer thickness.

Tribological Properties of Borided AISI 4140 Steel with the Powder Pack-Boriding Method

The present study evaluates the tribological properties of boride layers on the surface of AISI 4140 steel, formed using the pack-boriding method. Commercial EKabor®2 was used as the boronizing agent and the treatment was carried out at 900, 950, 1000, and 1050 °C for 2, 4, and 6 h, respectively. X-ray diffraction (XRD), scanning electron microscopy (SEM), and microhardness tests were used to characterize the phase composition, microstructure, and local hardness, respectively, of the borided steel samples. Block-on-disc tests were used to investigate tribological properties. Abrasive wear tests were carried out using emery paper at a fixed sliding speed and three different loads. Adhesive wear tests were executed against AISI 52100 steel at a fixed load and distance. The coefficient of friction values (COF) of the samples were determined simultaneously during the tests. The weight loss and COF of the borided samples were compared with untreated samples and the results suggest that both wear resistance and friction properties of the AISI 4140 steel improve with boriding.