I. Ozbek

Mechanical properties of boronized AISI W4 steel

Abstract A series of experiments was performed to evaluate some mechanical properties of boronized AISI W4 steel. Boronizing was carried out in a solid medium consisting of EKabor powders at 850, 950 and 1050°C for 2, 4, 6 and 8 h. After boronizing, FeB and Fe 2 B phases were formed on the surface of the steel substrate. A boride layer was revealed by a classical metallographic techniques and X-ray diffraction (XRD) analysis. Depending on the process temperature and boronizing time, the thickness of the coating layers ranged from 8 to 386 μm. Metallographic studies revealed that the boride layer has a lenticular morphology. The hardness of the boride layer was measured using a Vickers indenter with loads of 0.5 and 1 N. It was found that the hardness of the boride layers ranged from 1407 to 2093 HV. The fracture toughness of borided surfaces was measured via a Vickers indenter with a load of 10 N. It was observed that the fracture toughness of the boride layer ranged from 1.39 to 6.40 MPa m 1/2 . A longer boronizing time results in a greater boride layer thickness. Lengthwise cracks were formed on the samples that were borided at 1050°C for 6 and 8 h. The distribution of alloying elements from the surface to the interior was determined using energy-dispersive X-ray spectroscopy (EDS). The main aim of present study was to increase the service life of AISI W4 plain carbon tool steel.

Mechanical behavior of borides formed on borided cold work tool steel

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 .

Kinetics of boriding of AISI W1 steel

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.

Boriding response of AISI W1 steel and use of artificial neural network for prediction of borided layer properties

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.

The characterization of borided 99.5% purity nickel

Abstract A series of experiments were performed to evaluate some properties of borided 99.5% purity nickel. Boronizing was carried out in a solid media consisting of Ekabor powders at 950°C for 2, 4, and 8 h, respectively. Data on intermetallic silicides and borides (Ni 5 Si 2 , Ni 2 B) that formed on the surface of nickel substrate during boronizing were confirmed by a classical metallographic technique and X-ray diffraction (XRD) analysis. It was observed that the predominant phase in the coating layer was a silicide. It is probable that the formation of the nickel silicide layer was due to silicon in the boronizing powder. The hardness of silicides was measured by using a Vickers indenter with a load of 0.5 N. The microhardness of silicides formed on the surface of the nickel substrate reached up to 805 HV. Metallographic studies revealed that the silicide layer has an equiaxed granular morphology, whereas the boride layer formed had a needle-shaped structure. Depending on process temperature and boronizing time the thickness of coating layers ranged from 123 to 281 μm. The thickness of silicide and boride layers depended strongly on the processing time at 950°C. The longer boronizing time resulted in the thicker surface layer. The distribution of alloying elements from the surface to the interior was determined using energy dispersive X-ray spectroscopy (EDS).

An investigation on borided AISI 1020 steel

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.