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Cuma Bindal - One of the best experts on this subject based on the ideXlab platform.
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Investigation of diffusion kinetics of plasma paste borided AISI 8620 steel using a mixture of B_ 2 O_ 3 paste and B_ 4 C/SiC
Sadhana, 2013Co-Authors: Ibrahim Gunes, Cuma Bindal, Ibrahim Taktak, Yilmaz Yalcin, Sukru Ulker, Yusuf KayaliAbstract:In the present study, AISI 8620 steel was plasma paste borided by using various B_2O_3 paste mixture. The plasma paste boriding process was carried out in a dc plasma system at temperatures of 973, 1023 and 1073 K for 2, 5 and 7 h in a gas mixture of 70% H_2 -30% Ar under a constant pressure of 10 mbar. The properties of the boride layer were evaluated by optical microscopy, X-ray diffraction, Vickers micro-hardness tester and the growth kinetics of the boride layers. X-ray diffraction analysis of boride layers on the surface of the steel revealed FeB and Fe_2B phases. Depending on temperature and layer thickness, the activation energies of boron in steel were found to be 124.7 kJ/mol for 100% B_2O_3.
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An investigation on borided AISI 1020 steel
2013Co-Authors: I. Altinsoy, Ibrahim Ozbek, Mediha Ipek, F.g. Celebi Efe, S. Zeytin, Cuma BindalAbstract:In this study, we investigated some properties of borided AISI 1020 steel. Boronizing heat treatment was carried out at 800°C, 875°C and 950°C for 2, 4, 6 and 8 h using Ekabor 1 powders. The hardness of Borides formed on the steel substrate measured via Vickers indenter was about 1500 HVN. The thickness of boride layers depending on the process temperature and time was ranged from 20.5 to 216 μm. The presence of Fe2B boride was determined by XRD analysis. SEM microscope studies showed that the Borides formed on the AISI 1020 steel have columnar nature. Kinetics studies reveal a parabolic relationship between layer depth and process time, and the activation energy is calculated as 164,356 kJ/mol. Moreover, an attempt was made to investigate the possibility of predicting the iso-thickness of boride layer and to establish an empirical relationship between process parameters of boriding and boride layer for industrial applications.
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Kinetics of borided 31CrMoV9 and 34CrAlNi7 steels
Materials Characterization, 2008Co-Authors: Gozde Celebi Efe, Ibrahim Ozbek, Mediha Ipek, Cuma BindalAbstract:Abstract In this study, kinetics of Borides formed on the surface of 31CrMoV9 and 34CrAlNi7 steels borided in solid medium consisting of Ekabor II at 850–900–950 °C for 2, 4, 6 and 8 h were investigated. Scanning electron microscopy and optical microscopy examinations showed that Borides formed on the surface of borided steels have columnar morphology. The Borides formed in the coating layer confirmed by X-ray diffraction analysis are FeB, Fe2B, CrB, and Cr2B. The hardnesses of boride layers are much higher than that of matrix. It was found that depending on process temperature and time the fracture toughness of boride layers ranged from 3.93 to 4.48 MPa m1/2 for 31CrMoV9 and from 3.87 to 4.40 MPa m1/2 for 34CrAlNi7 steel. Activation energy, growth rate and growth acceleration of boride layer calculated according to these kinetic studies revealed that lower activation energy results in the fast growth rate and high growth acceleration.
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a comparison of Borides formed on aisi 1040 and aisi p20 steels
Materials & Design, 2007Co-Authors: I Uslu, Mediha Ipek, H Comert, F G Celebi, O Ozdemir, Cuma BindalAbstract:Abstract In this study, some properties of Borides formed on the AISI 1040 and AISI P20 steel substrates were investigated. Boronizing was performed at 800, 875, and 950 °C for 2, 4, 6, and 8 h by using Ekabor 2 powders. The hardness of Borides was about 1500 HVN. The depth of boride layers was ranged from 10 μm to 180 μm. The presence of Borides (e.g. FeB, Fe2B, MnB, and CrB) was confirmed by X-ray diffraction (XRD) analysis technique. XRD studies indicated that Borides formed on the AISI 1040 are dominantly FeB and Fe2B. Whereas, Borides formed on the AISI P20 mold steel are MnB and CrB in addition to FeB and Fe2B. Optical and SEM cross-sectional examinations revealed that boride formed on the AISI 1040 has columnar morphology and the AISI P20 has columnar and dense structure. The fracture toughness of Borides formed on AISI 1040 steel ranged from 3.2 MPa m1/2 to 5.1 MPa m1/2, and from 2.79 MPa m1/2 to 4.79 MPa m1/2 for AISI P20 mold steel. Kinetic studies show a parabolic relationship between layer thickness and process time, and the activation energy is 168 kJ/mol K for AISI 1040 and 200 kJ/mol K for AISI P20 mold steel. Growth kinetics of the borided layer was analyzed by measuring the extent of penetration of the FeB and Fe2B to substrates as a function of boriding time and temperature. The distribution of alloying elements from surface to interior was determined by using energy-dispersive X-ray spectroscopy (EDS).
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Evaluation of Borides formed on AISI P20 steel
Materials & Design, 2007Co-Authors: I Uslu, Mediha Ipek, H Comert, O Ozdemir, Cuma BindalAbstract:Abstract This study reports on an evaluation of Borides formed on AISI P20 steel substrate. Boronizing was performed at 800, 875 and 950 °C for 2, 4, 6 and 8 h by using Ekabor 2 powders. The hardness of Borides measured by means of Vickers indenter was about 1500 HVN. The depth of boride layers depending on temperature and process time was ranged from 10 to 180 μm. The presence of Borides (e.g., FeB, Fe2B, MnB, CrB) was confirmed by X-ray diffraction (XRD) analysis technique. SEM cross-sectional examinations revealed that Borides formed on AISI P20 has columnar morphology. Depending on the process time, fracture toughness of Borides formed on the surface of AISI P20 mold steel ranged from 2.79 to 4.79 MPa m1/2. Kinetic studies show a parabolic relationship between layer thickness and process time, and the activation energy is calculated as 200 kJ/mol. 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 of boriding and boride layer.
Aleksandra Pertek - One of the best experts on this subject based on the ideXlab platform.
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Microstructure and properties of laser-borided 41Cr4 steel
Optics and Laser Technology, 2013Co-Authors: Michael Kulka, Natalia Makuch, Aleksandra PertekAbstract:Abstract Laser-boriding, instead of diffusion-boriding, was applied to formation of boride layers on 41Cr4 steel. The microstructure and properties of these layers were compared to those obtained after typical diffusion-boriding. Three zones characterized the microstructure of laser-borided layer: laser-borided zone, hardened medium-carbon zone (heat affected zone) and medium-carbon substrate without heat treatment. The through-hardened laser-borided steel was also analyzed. In this case two zones characterized the microstructure: laser-borided zone and hardened medium-carbon substrate. The microstructure of laser-borided zone consisted of eutectic mixture of Borides and martensite. This phase composition (especially martensite presence) was the reason for microhardness decrease at the surface in comparison with diffusion-borided steel. However, the use of laser-boriding causes the decrease in microhardness gradient between the surface and the substrate in comparison with typical diffusion-boriding process. The value of mass wear intensity factor of the hardened laser-borided layer was comparable to that obtained in case of diffusion-boriding and through-hardening. The use of laser-borided layers instead of typical diffusion-borided layers may be advantageous under conditions of high abrasive wear of mating parts. For the experimental condition used, the laser-boriding process presented worst results concerning the fatigue strength. The cracks formed on the surface during laser re-melting were the reason for relatively quick first fatigue crack. In case of elements, which require high fatigue strength, the use of modified laser processing parameters would be necessary. The better results should be obtained by increasing of tracks overlapping. Although the cohesion of laser-borided layer was sufficient, the diffusion-borided layer showed a better cohesion.
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Microstructure and properties of borocarburized and laser-modified 17CrNi6-6 steel
Optics and Laser Technology, 2012Co-Authors: Michael Kulka, Natalia Makuch, Aleksandra Pertek, Adam PiaseckiAbstract:Abstract Two-step process: carburizing followed by boriding was applied to the formation of borocarburized layers. The boride layer formed on the substrate of changeable chemical and phase composition (e.g. borocarburized layer) was called “gradient boride layer”, in contrast to “typical boride layer”, formed on the substrate of constant chemical and phase composition. Until now, the typical heat treatment of borocarburized layer consisted of treatment through hardening: quenching in oil and low-temperature tempering. In this paper, instead of treatment through hardening, laser-heat treatment was employed. The properties of such layer were compared to the properties of typical carburized layer. Three zones characterized the microstructure of laser-modified borocarburized layer: iron Borides (FeB+Fe 2 B) of modified morphology, hardened carburized zone (heat affected zone) and carburized layer without heat treatment. X-ray microanalysis indicated the increased boron concentration close to the surface due to the occurrence of a mixture of FeB and Fe 2 B Borides. Near to the hardened carburized zone, Fe 2 B phase occurred in the laser-modified boride zone. Laser-heat treated borocarburized layer was characterized by higher microhardness at the surface than that obtained in case of carburized layer. It was caused by the iron Borides (FeB+Fe 2 B) occurrence at the surface, as a consequence of boriding process. However, the carburized layer was characterized by considerably larger hardened zone. Higher abrasive wear resistance, but lower low-cycle fatigue strength in comparison with the carburized layer, characterized the gradient boride layer formed by borocarburizing and laser surface modification. The indentation craters obtained on the surface of laser-heat treated borocarburized layer revealed sufficient cohesion (HF3 standard). The use of laser-modified borocarburized layers may be advantageous under conditions of high abrasive wear of mating parts. In case of parts, which require high resistance to fatigue, the carburized layer is irreplaceable.
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the importance of carbon concentration depth profile beneath iron Borides for low cycle fatigue strength
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011Co-Authors: Michael Kulka, Aleksandra Pertek, Natalia MakuchAbstract:Abstract Two-step process: carburizing followed by boriding was applied to the formation of borocarburized layers. The boride layer formed on the substrate of changeable chemical and phase composition (e.g. borocarburized layer) was called “gradient boride layer”, in contrast to “typical boride layer”, formed on the substrate of constant chemical and phase composition. Two borocarburized layers, of different carbon concentration–depth profiles in carburized zone, were investigated. Higher abrasive wear resistance, but lower low-cycle fatigue strength characterized both layers in comparison with the carburized layer. The influence of carbon concentration–depth profile beneath iron Borides on low-cycle fatigue strength was analyzed. The results showed that carburized zone beneath iron Borides had to meet the same requirements, which are characteristic of carburized layers of high fatigue resistance. The “ideal” carbon concentration–depth profile beneath iron Borides should be characterized by: relatively low carbon concentration beneath iron Borides, providing a limited amount of retained austenite; adequately low core carbon content; and relatively high case depth. As a result, the fatigue performance of borocarburized layer can approach a limit obtained for carburized layer.
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Gradient formation of boride layers by borocarburizing
Applied Surface Science, 2008Co-Authors: Michael Kulka, Aleksandra PertekAbstract:Abstract In this study borocarburizing was used for the formation of gradient boride layers. The microstructure, microhardness profiles and the low-cycle fatigue strength during radial compression of carburized, borided and borocarburized layer have been compared. The gradient borocarburized layers, formed by boriding of previously carburized substrate, are characterized by two zones in diffusion layer: iron Borides zone and carburized zone. After borocarburizing the iron Borides show a tendency towards a loss of the needle-like nature. The hardness gradient between iron Borides and low-carbon substrate is reduced. The microhardness beneath the iron Borides decreases to 900 HV in carburized zone and next gradually decreases to 400–450 HV in the core of steel. The highest resistance to low-cycle fatigue during radial compression has been observed in case of carburized and through hardened layer. The fatigue strength of gradient boride layer (borocarburized and through hardened) is a little lower. The typical borided and through hardened layer is characterized by the lowest resistance to low-cycle fatigue during radial compression. The profiles of stresses after boriding and borocarburizing have been compared. The obtained profile of stresses and the lower values of tensile stresses at the surface can be the reason for higher frictional wear resistance of borocarburized layers and for higher fatigue strength of these layers, too.
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laser surface modification of carburized and borocarburized 15crni6 steel
Materials Characterization, 2007Co-Authors: Michael Kulka, Aleksandra PertekAbstract:The paper presents the results of laser heat treatment (LHT) of carburized and borocarburized 15CrNi6 low-carbon steel. Laser tracks were arranged by CO{sub 2} laser beam as multiple tracks formed in the shape of a helical line. The microstructure and properties of these diffusion layers were compared with those obtained after through-hardening. The microstructure after carburizing and LHT consists of adjacent characteristic zones: re-melted zone (coarse-grained martensite), carburized layer with heat affected zone (fine acicular martensite), carburized layer without heat treatment and the substrate (ferrite and pearlite). The highest measured microhardness (about 820 HV) was observed in re-melted and heat affected zones. The increase of distance from the surface was accompanied by a gradual decrease of microhardness up to 400 HV beneath the HAZ and up to 250 HV in the core of steel. The carburized layer after LHT exhibited a higher resistance to frictional wear compared to a carburized layer after through-hardening. The microstructure after borocarburizing and LHT consists of the following characteristic zones: iron Borides of laser-modified morphology (FeB and Fe{sub 2}B), carburized layer with heat affected zone (martensite and alloyed cementite), carburized layer without heat treatment and the substrate (ferrite and pearlite). The highest microhardness was obtainedmore » in the iron boride zone. The microhardness of FeB boride extended up to 2200 HV and for the Fe{sub 2}B boride up to about 1300-1600 HV. With increased distance from the surface, the microhardness gradually decreases to 800 HV in HAZ, 400-450 HV in the carburized layer without heat treatment and to 250 HV in low-carbon substrate. The iron Borides after LHT assume a globular shape, which leads to a lower texture and porosity of the borided layers. The increased resistance to friction wear of the borocarburized layers is certified in comparison with the borided layer after conventional heat treatment (through-hardening)« less
Michael Kulka - One of the best experts on this subject based on the ideXlab platform.
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Liquid Boriding of Cp-Ti and Ti6Al4V Alloy: Characterization of Boride Layers and Tribological Properties
Surface Engineering and Applied Electrochemistry, 2020Co-Authors: Mourad Keddam, Natalia Makuch, Adam Piasecki, Andrzej Miklaszewski, B. Boumaali, Michael KulkaAbstract:Commercially pure titanium Cp-Ti and Ti6Al4V alloy were liquid borided using a borate bath consisting of 70% borax and 30% SiC at 1000°C for 3, 6, and 12 h. The borided materials were characterized by scanning electron microscopy to reveal the produced microstructures. Two kinds of titanium Borides were identified by the X-ray diffraction analysis (TiB2 on the top of the surface followed by TiB whiskers penetrating into the substrate). The kinetics of formation of titanium Borides was also investigated. The hardness of titanium Borides was measured by means of the Vickers indenter. The generated Ti Borides were characterized by high values of surface hardness. The wear resistance of borided materials (at 1000°C for 12 h) was analyzed by measuring the relative mass loss in comparison with that of the untreated materials. In addition, the wear mechanism was elucidated for both borided and untreated materials. As a result, liquid boriding was found efficient for improving the wear resistance of both materials.
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Corrosion Behavior of Hard Boride Layer Produced on Nimonic 80A-Alloy by Gas Boriding
Transactions of the Indian Institute of Metals, 2017Co-Authors: Natalia Makuch, Michael Kulka, D. MikołajczakAbstract:The gas boriding in N_2–H_2–BCl_3 atmosphere was applied in order to produce a wear resistant surface layer on Nimonic 80A-alloy samples. The microstructure, microhardness and corrosion resistance of the boride layer were investigated. The produced layer consisted mainly of the compact boride zone (with average thickness 71 μm), including the mixture of nickel and chromium Borides of high hardness (up to 1861 HV). In order to evaluate the corrosion behavior, the two methods of corrosion tests were used: potentiodynamic corrosion test in 5% NaCl solution and immersion corrosion test in a boiling solution of H_2O, H_2SO_4 and Fe_2(SO_4)_3. The results showed that gas boriding could provide the excellent corrosion resistance if the whole surface of a Nimonic 80A-alloy sample was covered by the continuous boride layer. Otherwise, as a consequence of selective boriding, the significant difference in electrochemical potentials caused an accelerated uniform corrosion of the base material. Graphical Abstract
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Microstructure and properties of laser-borided 41Cr4 steel
Optics and Laser Technology, 2013Co-Authors: Michael Kulka, Natalia Makuch, Aleksandra PertekAbstract:Abstract Laser-boriding, instead of diffusion-boriding, was applied to formation of boride layers on 41Cr4 steel. The microstructure and properties of these layers were compared to those obtained after typical diffusion-boriding. Three zones characterized the microstructure of laser-borided layer: laser-borided zone, hardened medium-carbon zone (heat affected zone) and medium-carbon substrate without heat treatment. The through-hardened laser-borided steel was also analyzed. In this case two zones characterized the microstructure: laser-borided zone and hardened medium-carbon substrate. The microstructure of laser-borided zone consisted of eutectic mixture of Borides and martensite. This phase composition (especially martensite presence) was the reason for microhardness decrease at the surface in comparison with diffusion-borided steel. However, the use of laser-boriding causes the decrease in microhardness gradient between the surface and the substrate in comparison with typical diffusion-boriding process. The value of mass wear intensity factor of the hardened laser-borided layer was comparable to that obtained in case of diffusion-boriding and through-hardening. The use of laser-borided layers instead of typical diffusion-borided layers may be advantageous under conditions of high abrasive wear of mating parts. For the experimental condition used, the laser-boriding process presented worst results concerning the fatigue strength. The cracks formed on the surface during laser re-melting were the reason for relatively quick first fatigue crack. In case of elements, which require high fatigue strength, the use of modified laser processing parameters would be necessary. The better results should be obtained by increasing of tracks overlapping. Although the cohesion of laser-borided layer was sufficient, the diffusion-borided layer showed a better cohesion.
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Microstructure and properties of borocarburized and laser-modified 17CrNi6-6 steel
Optics and Laser Technology, 2012Co-Authors: Michael Kulka, Natalia Makuch, Aleksandra Pertek, Adam PiaseckiAbstract:Abstract Two-step process: carburizing followed by boriding was applied to the formation of borocarburized layers. The boride layer formed on the substrate of changeable chemical and phase composition (e.g. borocarburized layer) was called “gradient boride layer”, in contrast to “typical boride layer”, formed on the substrate of constant chemical and phase composition. Until now, the typical heat treatment of borocarburized layer consisted of treatment through hardening: quenching in oil and low-temperature tempering. In this paper, instead of treatment through hardening, laser-heat treatment was employed. The properties of such layer were compared to the properties of typical carburized layer. Three zones characterized the microstructure of laser-modified borocarburized layer: iron Borides (FeB+Fe 2 B) of modified morphology, hardened carburized zone (heat affected zone) and carburized layer without heat treatment. X-ray microanalysis indicated the increased boron concentration close to the surface due to the occurrence of a mixture of FeB and Fe 2 B Borides. Near to the hardened carburized zone, Fe 2 B phase occurred in the laser-modified boride zone. Laser-heat treated borocarburized layer was characterized by higher microhardness at the surface than that obtained in case of carburized layer. It was caused by the iron Borides (FeB+Fe 2 B) occurrence at the surface, as a consequence of boriding process. However, the carburized layer was characterized by considerably larger hardened zone. Higher abrasive wear resistance, but lower low-cycle fatigue strength in comparison with the carburized layer, characterized the gradient boride layer formed by borocarburizing and laser surface modification. The indentation craters obtained on the surface of laser-heat treated borocarburized layer revealed sufficient cohesion (HF3 standard). The use of laser-modified borocarburized layers may be advantageous under conditions of high abrasive wear of mating parts. In case of parts, which require high resistance to fatigue, the carburized layer is irreplaceable.
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the importance of carbon concentration depth profile beneath iron Borides for low cycle fatigue strength
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011Co-Authors: Michael Kulka, Aleksandra Pertek, Natalia MakuchAbstract:Abstract Two-step process: carburizing followed by boriding was applied to the formation of borocarburized layers. The boride layer formed on the substrate of changeable chemical and phase composition (e.g. borocarburized layer) was called “gradient boride layer”, in contrast to “typical boride layer”, formed on the substrate of constant chemical and phase composition. Two borocarburized layers, of different carbon concentration–depth profiles in carburized zone, were investigated. Higher abrasive wear resistance, but lower low-cycle fatigue strength characterized both layers in comparison with the carburized layer. The influence of carbon concentration–depth profile beneath iron Borides on low-cycle fatigue strength was analyzed. The results showed that carburized zone beneath iron Borides had to meet the same requirements, which are characteristic of carburized layers of high fatigue resistance. The “ideal” carbon concentration–depth profile beneath iron Borides should be characterized by: relatively low carbon concentration beneath iron Borides, providing a limited amount of retained austenite; adequately low core carbon content; and relatively high case depth. As a result, the fatigue performance of borocarburized layer can approach a limit obtained for carburized layer.
Ibrahim Ozbek - One of the best experts on this subject based on the ideXlab platform.
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An investigation on borided AISI 1020 steel
2013Co-Authors: I. Altinsoy, Ibrahim Ozbek, Mediha Ipek, F.g. Celebi Efe, S. Zeytin, Cuma BindalAbstract:In this study, we investigated some properties of borided AISI 1020 steel. Boronizing heat treatment was carried out at 800°C, 875°C and 950°C for 2, 4, 6 and 8 h using Ekabor 1 powders. The hardness of Borides formed on the steel substrate measured via Vickers indenter was about 1500 HVN. The thickness of boride layers depending on the process temperature and time was ranged from 20.5 to 216 μm. The presence of Fe2B boride was determined by XRD analysis. SEM microscope studies showed that the Borides formed on the AISI 1020 steel have columnar nature. Kinetics studies reveal a parabolic relationship between layer depth and process time, and the activation energy is calculated as 164,356 kJ/mol. Moreover, an attempt was made to investigate the possibility of predicting the iso-thickness of boride layer and to establish an empirical relationship between process parameters of boriding and boride layer for industrial applications.
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Kinetics of borided 31CrMoV9 and 34CrAlNi7 steels
Materials Characterization, 2008Co-Authors: Gozde Celebi Efe, Ibrahim Ozbek, Mediha Ipek, Cuma BindalAbstract:Abstract In this study, kinetics of Borides formed on the surface of 31CrMoV9 and 34CrAlNi7 steels borided in solid medium consisting of Ekabor II at 850–900–950 °C for 2, 4, 6 and 8 h were investigated. Scanning electron microscopy and optical microscopy examinations showed that Borides formed on the surface of borided steels have columnar morphology. The Borides formed in the coating layer confirmed by X-ray diffraction analysis are FeB, Fe2B, CrB, and Cr2B. The hardnesses of boride layers are much higher than that of matrix. It was found that depending on process temperature and time the fracture toughness of boride layers ranged from 3.93 to 4.48 MPa m1/2 for 31CrMoV9 and from 3.87 to 4.40 MPa m1/2 for 34CrAlNi7 steel. Activation energy, growth rate and growth acceleration of boride layer calculated according to these kinetic studies revealed that lower activation energy results in the fast growth rate and high growth acceleration.
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The characterization of borided pure tungsten
Surface and Coatings Technology, 2005Co-Authors: Metin Usta, Ibrahim Ozbek, Cuma Bindal, Mediha Ipek, A.h. UcisikAbstract:This study reports on mechanical properties of borided pure tungsten. Boronizing heat treatment was performed in a solid medium consisting of Ekabor powders at 940 °C for 2, 4, and 8 h. The presence of WB on the surface of pure tungsten was confirmed by XRD analysis. Metallographic studies revealed an almost uniform and compact boride layer on the surface of the pure tungsten. The thickness of boride layer ranged from 10 to 42 μm with some scatters. The hardness of borided specimens decreased with the distance from the surface to the interior of the test material. The hardness of the boride on the substrate was 2500 HV while the hardness of the substrate was 445 HV.
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Kinetics of boriding of AISI W1 steel
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2002Co-Authors: Kenan Genel, Ibrahim Ozbek, Cuma BindalAbstract:Abstract A technologically interesting characteristic of boriding is the production of a hard, wear-resistant coating layer on the steel substrate. In this study, case properties of borided AISI W1 steel has been investigated by conducting a series of experiments in Ekabor-I powders at the process temperature of 1123–1323 K at 50 K intervals for periods of 1–8 h. The presence of Borides FeB and Fe 2 B formed on the surface of steel substrate was confirmed by optical microscopy and X-ray diffraction. Cross-sectional observation in the optical microscope revealed smooth and compact morphology of the borided layer. The distribution of alloy elements from the surface to the interior was confirmed by energy dispersive X-ray spectroscopy. The hardness of the boride layer formed on the surface of the steel substrate was higher than 1500 HV. It was concluded that the optimum temperature for AISI W1 steel borided in Ekabor-I powders was approximately 1223 K for hardness in 10 μm depth, and the hardness change with boriding temperature was related to the grain size of the treated steel. The kinetics of boriding show a parabolic relationship between layer thickness and process time, and the activation energy for the process is 171.2±16.6 kJ mol −1 . 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 of boriding and boride layer.
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Boriding response of AISI W1 steel and use of artificial neural network for prediction of borided layer properties
Surface and Coatings Technology, 2002Co-Authors: Kenan Genel, Ibrahim Ozbek, Akif Kurt, Cuma BindalAbstract:Abstract In the present study, boriding response of AISI W1 steel and prediction of boride layer properties were investigated by using artificial neural network (ANN). Boronizing heat treatment was carried out in a solid medium consisting of Ekabor-I powders at 850–1050 °C at 50 °C intervals for 1–8 h. The substrate used in this study was AISI W1. The presence of Borides FeB and Fe 2 B formed on the surface of steel substrate was confirmed by optical microscope and X-ray diffraction analysis. The hardness of the boride layer formed on the surface of the steel substrate was over 1500 VHN. Experimental results indicated that there is a nearly parabolic relationship between boride layer and process time for higher temperatures. Optical microscope cross-sectional observation of the borided layer revealed columnar and compact morphology. Moreover, an attempt was made to investigate possibility of predicting the hardness and depth of boride layer variation and establish some empirical relationship between process parameter of boriding and boride layer, and hardness changes using back-propagation learning algorithm in ANN. Modelling results have shown that hardness and depth of boride layer were predicted with high accuracy by ANN.
Saduman Sen - One of the best experts on this subject based on the ideXlab platform.
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an approach to kinetic study of borided steels
Surface & Coatings Technology, 2005Co-Authors: Saduman Sen, Ugur Sen, Cuma BindalAbstract:Abstract In present study, kinetic studies on borided AISI 5140, AISI 4340 and AISI D2 steels are reported. Steels were borided in a salt bath consisting of borax, boric acid and ferro-silicon between 1073 and 1273 K for 2, 4, 6 and 8 h. The morphology and types of Borides formed on the surface of steel substrates were confirmed by optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. Boride layer thickness formed on the borided steels ranged from 21 to 238 μm depending on process temperature, treatment time and alloying elements of the substrates. The hardness of Borides formed on the samples changes between 1077 and 2140 HV0.1 according to treatment time and temperature. Layer growth kinetics were analyzed by measuring the extent of penetration of FeB and Fe2B sublayers as a function of boronizing time and temperature in the range of 1123–1273 K. The depth of the tips of the most deeply penetrated FeB and Fe2B needles are taken as measures for diffusion in the growth directions. The kinetics of the reaction, K=Ko exp (−Q/RT), have also been determined by varying the boriding temperature and time. The results showed that K increase with boriding temperature. Activation energies (Q) of borided AISI 5140, AISI 4340 and AISI D2 steels at present study were determined as 223, 234 and 170 kJ/mol, respectively. Moreover, an attempt was made to investigate the possibility of predicting the contour diagrams of boride layers variation and to establish some empirical relationships between process parameters and boride layer thicknesses.
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the growth kinetics of Borides formed on boronized aisi 4140 steel
Vacuum, 2005Co-Authors: Saduman Sen, Ugur Sen, C BindalAbstract:Abstract The growth kinetics of boride layer on boronized AISI 4140 steel is reported. Steel samples were boronized in molten borax, boric acid and ferro-silicon bath at 1123, 1173 and 1223 K for 2, 4, 6 and 8 h, respectively. The morphology and types of Borides formed on the surface of AISI 4140 steel substrate were analyzed by means of optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction analysis (XRD). The boride layer thickness ranged from 38.4 to 225 μm. Iso-thickness diagrams for pre-determined thickness according to treatment time and temperature, were graphed by MATLAB 6.0 software. The hardness of Borides formed on the samples changed between 1446 and 1739 HV0.1, according to treatment time and temperature. Layer growth kinetics way analyzed by measuring the extent of penetration of FeB and Fe2B sublayers as a function of treatment time and temperature in the range of 1123–1223 K. For practical use, an iso hardness diagram was established as a function of treatment time, temperature and boride layer thickness. The depth of the tips of the most deeply penetrated FeB and Fe2B needles were taken as measures for diffusion in the growth directions. The kinetics of the reaction, K = K o exp ( - Q / RT ) were also determined by varying the treatment temperature and time. The results show that K increased with boronizing temperature. The activation energy (Q) was formed to be 215 kJ mol−1. The growth rate constant (K) ranged from 3×10−9 to 2×10−8 cm2s−1.
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the fracture toughness of Borides formed on boronized cold work tool steels
Materials Characterization, 2003Co-Authors: Ugur Sen, Saduman SenAbstract:Abstract In this study, the fracture toughness of boride layers of two borided cold work tool steels have been investigated. Boriding was carried out in a salt bath consisting of borax, boric acid, ferro-silicon and aluminum. Boriding was performed at 850 and 950 °C for 2 to 7 h. The presence of boride phases were determined by X-ray diffraction (XRD) analysis. Hardness and fracture toughness of Borides were measured via Vickers indenter. Increasing of boriding time and temperature leads to reduction of fracture toughness of Borides. Metallographic examination showed that boride layer formed on cold work tool steels was compact and smooth.
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Mechanical behavior of Borides formed on borided cold work tool steel
Surface and Coatings Technology, 2001Co-Authors: Saduman Sen, Ibrahim Ozbek, Ugur Sen, Cuma BindalAbstract:Abstract In this study, some mechanical properties of borided cold work low-alloy tool steels were investigated. Boronizing was performed in a solid medium consisting of Ekabor-I powders at 1000°C for 2, 4 and 6 h. The substrate used in this study was high-carbon, low-alloy tool steel essentially containing 1.18 wt.% C, 0.70 wt.% Cr, 0.30 wt.% Mn, 0.10 wt.% V and 0.25 wt.% Si. The presence of Borides (FeB+Fe 2 B) formed on the surface of steel substrate was confirmed by optical microscope and X-ray diffraction (XRD) analysis. The hardness of the boride layer formed on the surface of the steel substrate and unborided steel substrate were 1854 and 290 kg/mm 2 , respectively. Experimental results revealed that longer boronizing time resulted in thicker boride layers. Optical microscope cross-sectional observation of the borided layers revealed denticular morphology. The fracture toughness of the boride layers measured by means of a Vickers indenter with a load of 3 N was in the range of 2.52–3.07 MPa m 1/2 .