Browsing by Author "Hacisalihoglu, Ilyas"

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Characterization of the Structural and Tribological Properties of Medical Ti6Al4V Alloy Produced in Different Production Parameters Using Selective Laser Melting
(Mary Ann Liebert, Inc, 2019) Kaya, Gurkan; Yildiz, Fatih; Hacisalihoglu, Ilyas
The tribological properties of the parts produced by the selective laser melting (SLM) are greatly influenced by the parameters/strategies used in the production and the postproduction heat treatments. Therefore, it is very important to know and control the parameters to be used in production on the tribological properties of the material. In this study, the effects of build orientation, hatch spacing, and heat treatment on the wear performance of medical Ti6Al4V alloy were investigated. The tribological properties of the samples produced by SLM were compared with the tribological characteristics of the parts produced by conventional method (casting). It was determined that the wear resistance of Ti6Al4V alloy increased with the decreasing of hatch spacing in SLM and the wear resistance of the 45 degrees angle on the production table positively affected the relative density rate. The highest surface hardness among the samples was obtained as similar to 360 HV0.3 for the sample produced at the 60 mu m hatch spacing and 45 degrees build orientation, which was the highest densification rate obtained. The lowest wear rate value was obtained for the sample produced at 60 mu m hatch spacing and 45 degrees build orientation where the highest densification rate and highest surface hardness were obtained. The wear rate of this sample was 26% lower than the wear rate of the sample produced by the casting method. The most suitable build orientation was determined as 45 degrees in terms of wear resistance of the alloy.
The Effect of Geometry on Joint Strength in Adhesively Bonded Joints with the Same Adhesive Area
(Taylor & Francis Inc, 2024) Akpinar, Salih; Hacisalihoglu, Ilyas; Calik, Ahmet
Studies to increase the joint strength of adhesively bonded joints used in the aerospace and automotive sectors are met with interest in the field of engineering. Many different methods are used to increase the strength of the bonded joint, and one of these methods is to change the joint geometry. This study aims to increase the joint strength by changing the geometry of the joint with the same adhesive area condition. In the study, the DP460 structural adhesive was used as the adhesive, the AA2024-T3 aluminum alloy was used as the adherend, and the One Step-Lap Joint (OSLJ), Double-Strap Joint (DSJ), and Stepped Double-Strap Joint (SDSJ) was used as the joint types. The joint strengths of the joints obtained by using different step lengths and different patch lengths for these three types of joints with the same adhesive area were investigated experimentally and numerically. Firstly, the strengths of the SLJ type obtained by using four different step lengths and the DSJ type obtained by using patches of four different lengths were investigated. In the light of these investigations, the mechanical properties of the joints obtained by changing the step length and patch length in the SDSJ type, a new joint type with the same adhesive area, were obtained. As a result, compared to the OSLJ type with the same adhesive area, the joint strength of the DSJ type increases by approximately 45% to 67%. In addition, while the strength of the new type of joint (SDSJ) obtained in the presented study increases between 7% and 35% according to the DSJ type, it increases between 56% and 126% according to the OSLJ type. These increases in the joint strength vary according to the bonding area. Additionally, in the presented study, experimental data were compared with numerical analysis, and it was observed that the data were quite consistent with each other.
The Effect of Selective Laser Melting Process on the Microstructure, Density, and Electrical Conductivity of Silver-Coated Copper Cores
(Springer, 2021) Varol, Temel; Hacisalihoglu, Ilyas; Kaya, Gurkan; Guler, Onur; Yildiz, Fatih; Aksa, Huseyin Can; Akcay, Serhatcan Berk
In this study, compact materials were fabricated by selective laser melting (SLM) method using copper-silver core-shell particles obtained by electroless coating method. The effect of SLM parameters such as laser power, scanning speed and hatch spacing on the important properties such as microstructure, density and electrical conductivity of compacts produced from core-shell particles was investigated. This study significantly contributes to the fact that the parameters used in the fabrication of copper-silver-based materials with the SLM method directly affect the properties of the compacts. The results showed that the silver shell thickness obtained on the core of copper powders by electroless plating method varied between 1 and 3 mu m and was distributed homogeneously. It was also found that the highest apparent density value among all samples was obtained above about 99% from the sample where 100 W power, 250 mm/s scanning speed and 45% hatch spacing values were used. In addition the highest electrical conductivity value was obtained for these conditions.
The Effect of Stepped Notches and Recesses on Joint Strength in Adhesive Bonded Joints: Experimental and Numerical Analysis
(Elsevier, 2022) Hacisalihoglu, Ilyas; Akpinar, Salih
In this study, the strengths of single-lap joints (SLJ) obtained by creating stepped notches and recesses of different number of steps, lengths and depths in the adhered material were investigated experimentally and numerically. In the study, the DP460 structural adhesive was used as the adhesive, and the AA2024-T3 aluminum alloy was used as the adherend. Firstly, the strengths of the SLJ obtained by creating two-stepped and threestepped recesses of different lengths and thicknesses in the adhered were examined. Then, the strengths of the SLJ obtained by creating two-stepped and three-stepped notches of different lengths and thicknesses were examined. As a result of these examinations, the mechanical properties of the new SLJ geometry, in which the best two-stepped and three-stepped recessed and protruding joints were formed together, were obtained. As a result, while making two or three-stepped of the recess to the adherend in the adhesive joints increases the strength of the joint by approximately 33% to 40%, making two or three-stepped notches increases the strength of the joint by approximately 37% to 38%. However, in the case of gradual recess and notch in the joint being together, the joint strength increases by approximately 50% to 54%.
The Effects of Build Orientation and Hatch Spacing on Mechanical Properties of Medical Ti-6Al Alloy Manufactured by Selective Laser Melting
(Elsevier Science Sa, 2021) Hacisalihoglu, Ilyas; Yildiz, Fatih; celik, Ayhan
The mechanical properties of the parts manufactured by selective laser melting (SLM) method are immensely influenced by the parameters/strategies of manufacturing and the post-treatment. Therefore, it is of importance to determine the effect of parameters used during the manufacturing process on the mechanical properties of the material. In this study, the effects of build orientation and hatch spacing on static mechanical and impact properties of medical Ti-6Al-4V alloy manufactured by the SLM method were investigated, and 12 different hatch spacing were tested with 3 different build orientations. Increasing the hatch spacing resulted in a decline in the ultimate tensile strength values; however, there was a different trend in the elongation values. The elongation values increased up to 67.5 mu m and then decreased with increasing hatch spacing for the elongation values. The highest elongation values were obtained when the hatch spacing was 67.5 mu m for any of the three orientations. Besides, considering the absorbed energies of the samples manufactured by the SLM, the highest dynamic toughness value was obtained from the sample manufactured by horizontal orientation.
Effects of Fabrication Parameters and Post-Processing Treatments on the Mechanical and Tribological Behavior of Surface-Enhanced Copper Based Materials by Selective Laser Melting
(Elsevier Science Sa, 2022) Aksa, Huseyin Can; Hacisalihoglu, Ilyas; Yildiz, Fatih; Varol, Temel; Guler, Onur; Kaya, Gurkan; Akcay, Serhatcan Berk
Selective laser melting (SLM), which is an advanced manufacturing method developed in recent years, produces parts with complex shapes and critical dimensions using metallic powder and laser beam. In this study, copper based conductive materials with silver networks were fabricated by electroless silver coating and SLM. The effects of laser power, scanning speed, hatch spacing, build orientation and post treatments on the mechanical and tribological properties of SLM compacts manufactured from core-shell particles were investigated. After the mechanical tests, higher stress and elongation values were obtained in the sample positioned horizontally on the build platform with a laser power of 100 W, scanning speed of 250 mm/s and hatch spacing value of 45%. After that SLM process, the post-processes were applied to the samples and the physical and mechanical properties improved significantly. The highest density value was obtained by the rolling process at 900 ?, and an increase of approximately 35.6% was obtained compared to the sample without post-processing. The lowest wear rate among all samples was obtained in the hot-pressing process at 750 ?.
Investigation of the Structural and Tribological Properties of 316L Stainless Steel Manufactured Using Variable Production Parameters by Selective Laser Melting
(Springer, 2022) Gencoglu, Ufuk; Kaya, Gurkan; Erguder, T. Oguzhan; Hacisalihoglu, Ilyas; Yildiz, Fatih
The structural, tribological and mechanical properties of the engineering parts manufactured by the selective laser melting (SLM) method are highly affected by the strategies and parameters used in manufacturing. Therefore, it is extremely important to know/control the effect of the parameters to be used in manufacturing on the mechanical and tribological properties of the material and to determine the optimum production conditions. In this study, the effects of these fabrication parameters of SLM process on the structural, mechanical properties and wear performance of 316L stainless steel were investigated. Because many production parameters are involved in the SLM method, it was tried to save material and time by systematically reducing the manufacturing parameters. In experimental studies, the parameters of scanning speed, laser beam power and hatch spacing, which directly affect the laser energy density, were investigated. As a result, it was determined that the manufacturing parameters/strategies used in the SLM method have a significant effect on the mechanical properties and wear performance of 316L stainless steel. The lowest wear rate was obtained for the sample produced with 70% hatch spacing and 0 degrees build orientation. This sample also represented the parameter in which the highest microhardness and density ratio was obtained.
Tribocorrosion Behavior of Duplex Treated Pure Titanium in Simulated Body Fluid
(Elsevier Science SA, 2013) Albayrak, Cigdem; Hacisalihoglu, Ilyas; Vangolu, S. Yenal; Alsaran, Akgun
Commercially pure titanium (CP Ti) is widely used as an implant material, which has excellent corrosion resistance and high biocompatibility. However, pure Ti has poor tribological properties. For this reason, surface modification techniques and/or surface coatings have been applied on implant materials. For instance, plasma nitriding processes have been used to obtain protective coatings on pure Ti implants in order to improve their wear resistance and durability. In this study, a plasma nitriding process was applied on pure Ti substrates, which formed a hard compound layer consisting of TiN and Ti2N phases. An anodizing process was implemented on nitrided samples, which created a porous TiO2 oxide layer. Tribocorrosion tests were carried out with a reciprocating tribometer combined with a three-electrode cell. Tests were performed at open circuit potential (OCP), potentiostatic and potentiodynamic studies condition in Simulated Body Fluid (SBF). The OCP value and friction coefficient of duplex treated specimen under wear conditions were better compared to the other samples; nevertheless it was observed that the wear and the wear products were more effective during tribo-corrosion tests. (C) 2013 Elsevier B.V. All rights reserved.
Tribocorrosion Behavior of Plasma Nitrided Hardox Steels in NaCl Solution
(Elsevier Sci Ltd, 2018) Hacisalihoglu, Ilyas; Yildiz, Fatih; Celik, Ayhan
In this study, the effect of plasma nitriding treatment on structural, wear, corrosion and tribocorrosion properties of different type Hardox steels (400, 450 and 500 type) was investigated using X-ray diffraction, microhardness tester, scanning electron microscope, 3D profilometer and reciprocating wear tester coupled with electrochemical corrosion cell. The plasma nitriding treatments were performed in 50%N-2-50%H-2 gas mixture at 500 degrees C for 1 and 4 h. The tribological tests were carried out in dry and open circuit potential conditions at 10 N normal force in 3.5% wt. NaCl aqueous solution at room temperature. Nitriding changed the electrochemical degradation mechanism of surface to pitting corrosion. Plasma nitriding time of 1 h significantly improved the corrosion and wear resistance of the Hardox steels.
Tribological and Machining Performance of Tungsten Carbide Cutting Tool Material Coated with Different Carbon Nitride Films
(Inderscience Enterprises Ltd, 2022) Dumlu, Firat; Erguder, Tevfik Oguzhan; Kaya, Gurkan; Hacisalihoglu, Ilyas; Yildiz, Fatih
In this study, the tribological properties of tungsten carbide (WC) cutting tools coated with AlTiCN and CrCN ceramic films and their machining performance were investigated in both CNC vertical machining centre and lathe. The coatings were applied on end milling tools, lathe inserts and 12 x 12 x 5 mm sized test samples by cathodic arc physical vapour deposition (CAPVD) method. The plastic injection mould steel workpiece was machined with high-speed dry cutting by CNC vertical machining centre and with coolant by CNC lathe to determine the cutting and wear performance of coated and uncoated tools. According to the results, it was determined that AlTiCN has higher microhardness and adhesion value and lower wear rate value than CrCN. It was also determined that the tools coated with AlTiCN thin film have superior properties in terms of both mass loss and flank wear width after machining processes.
Tribological and Thermal Properties of Plasma Nitrided Ti45Nb Alloy
(Elsevier, 2021) Hacisalihoglu, Ilyas; Kaya, Gurkan; Erguder, T. Oguzhan; Mandev, Emre; Manay, Eyuphan; Yildiz, Fatih
In this study, the effects of plasma nitriding surface treatment on the structural, tribological and thermal properties of Ti45Nb Beta alloy were investigated experimentally. Plasma nitriding process of Ti45Nb alloy was performed in 25% Ar-75% N2 gas mixture, for treatment times of 1-4 hours at the temperatures of 700-750 degrees C. The tribological tests of the plasma nitrided alloy were performed in dry sliding conditions. Thermal property measurements were applied to the plasma nitrided samples to determine their thermal conductivity and specific heat capacity. The TiNbN2 phase was observed in the compound layer formed after the nitriding process, and the compound layer and diffusion layer thicknesses increased depending on the nitriding temperature and duration. The highest microhardness was obtained for the sample nitrided at 750 degrees C for 4 hours and the hardness approximately twice increased compared to the untreated alloy. Due to its high surface hardness and nitride layer with sufficient thickness, the lowest wear rate was obtained for the nitrided sample under these conditions. As a result, the most effective parameter on the wear properties of Ti45Nb alloy after nitriding was determined as the process temperature. After the plasma nitriding process, thermal conductivity, thermal diffusion and specific heat capacity values decreased due to the formation of a nitride layer on the surface with a relatively lower thermal conductivity compared to the untreated alloy.
Wear and Thermal Behavior of TiAlN Thin Films onto Ti6Al4V Alloy Manufactured by Selective Laser Melting Method
(Mary Ann Liebert, Inc, 2023) Kaya, Gurkan; Erguder, Tevfik Oguzhan; Hacisalihoglu, Ilyas; Mandev, Emre; Manay, Eyuphan; Yildiz, Fatih
In this study, it was targeted to enhance the tribological and thermal properties of Ti6Al4V alloys, which were manufactured with three different build orientations and hatch spacing by using the selective laser melting (SLM) method and a traditional method (casting). In addition, the surfaces of the samples produced by these two methods were coated with the TiAlN thin film by using the cathodic arc physical vapor deposition (CAPVD) method. After the experimental investigations, the lowest wear rate was obtained for the 60-90 degrees sample, and the highest microhardness value was measured as similar to 1070 HV0.1 for the 90-45 degrees sample. It was specified that the wear rate rose as the hatch spacing increased among the same build orientation Ti6Al4V alloys produced by SLM method. According to thermal analysis results, among the same hatch spacing values, it was determined that as the build orientation value increased, the specific heat capacity and thermal conductivity values decreased. Among the coated samples, the highest thermal conductivity and specific heat capacity values were obtained for casting samples as 5.63 (W/m center dot K) and 560.4 (J/kg center dot K), respectively.
Wear Performance of Different Nitride-Based Coatings on Plasma Nitrided AISI M2 Tool Steel in Dry and Lubricated Conditions
(Elsevier Science SA, 2017) Hacisalihoglu, Ilyas; Yildiz, Fatih; Alsaran, Akgun
AISI M2 high speed tool steel is one of the widely used materials in the machining industry. The most common problems of this material are wearing of the cutting edge and adhesion of the work materials to the tool during the machining operations. To overcome these disadvantages, single and duplex surface treatments combining a diffusion process and a thin film ceramic coating are performed. In this study, various nitride-based coatings (TiN, TiCN, AITiN and CrN) were deposited on untreated and plasma nitrided AISI M2 high speed tool steel specimens using cathodic arc physical vapour deposition (CAPVD) technique. The plasma nitriding treatment was performed in 50%N-2-50%H-2 gas mixture at 500 degrees C for 2 h. The influences of different surface treatments on structural properties of AISI M2 steel were investigated by means of field emission scanning electron microscope, X-ray diffractometer, focused ion beam milling system, microhardness tester and optical profilometer. The tribological properties of specimens were examined in dry and cutting fluid conditions by using reciprocating sliding wear test with Al2O3 ball as a counter material. According to tribological test results, the solely coating treatment was more effective in improvement of the wear resistance of AISI M2 high-speed tool steel rather than duplex treatment. The lowest worn volume was obtained from the solely CrN coated surface. Whereas under cutting fluid condition, solely TiN and TiCN coated surfaces showed higher wear resistance. It was also observed that the friction coefficients of all specimens tested in boron-containing cutting fluid were lower and quite stable compared with dry sliding condition. (C) 2017 Elsevier B.V. All rights reserved.