Yazar "Gülenç, Behçet" seçeneğine göre listele
Listeleniyor 1 - 12 / 12
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Analysis of mechanical and microstructural characteristics of AISI 430 stainless steel welded by GMAW(Redakcia Kovove Materialy, 2022) Acar, İsmail; Çevik, Bekir; Gülenç, BehçetThe use of stainless steels in the machine manufacturing industry is increasing day by day. Due to the poor corrosion properties of especially unalloyed and low-alloy steels, stainless steels are among the preferred materials in industrial applications because of their superiorities such as high corrosion resistance, very good forming and welding capabilities, hygiene and aesthetic appearance. The welding requirements of stainless steels with such widespread use potential are inevitable. For this reason, studies on welding joining stainless steels are important. In this study, AISI 430 ferritic stainless steel materials were joined using different shielding gas combinations through the gas metal arc welding (GMAW) method. In the welding operations, pure argon (100 % Ar), 97 % Ar + 3 % H-2, and 93 % Ar + 7% H-2 gas combinations were used. The effect of shielding gas combined with the mechanical and metallographic tests applied to the welded sheets on the mechanical and microstructural properties of AISI 430 stainless steel was investigated. In the results obtained from the study, a noticeable grain coarsening occurred in the microstructure of the weld metal and HAZs with the addition of H-2 to the Ar gas during the welding process. The highest tensile strength was obtained from the joints welded with 97 % Ar+3 % H-2 mixture gas. As a result of the tensile test, a rupture occurred in the base metal in all welded samples. No crack or tear defect was found in the weld zone due to the bending test.Öğe The effect of cold and hot reformation process to mechanical properties of deformed automobile chassis material(Kaunas Univ Technol, 2016) Gülenç, Behçet; Kocaman, Hamit; Çevik, Bekir; Durgutlu, Ahmet; Fındık, TayfunVehicles are damaged as a result of traffic accidents. Chassis and body parts of damaged vehicles are reformed by using cold and hot deformation methods. High-strength low alloy (HSLA) steel material coated (galvanised) with S320GD+Z quality (DIN EN 10326) zinc, which is used in chassis production, was used in this study. Steel sheet materials were damaged. Damaged automotive chassis material was reformed with cold and hot reformation processes. Tensile, notch impact, bending and hardness tests were applied to the reference material which were not deformed and materials to which reformation process was applied. In the light of obtained results, the effect of reformation process on mechanical properties of automotive sheet was determined.Öğe The Effect of Joining Process on Mechanical Properties of Structural Steels(Natl Acad Sciences Ukraine, Inst Metal Physics, 2010) Gülenç, Behçet; Uygur, I.; Tuncer, E.; Durgutlu, A.; Kap, T.; Uzunoğlu, M.Welding of structural steels is extensively used in various fields. In general, welding of these steels does not pose any problems. They may be welded with almost all well-known welding techniques. Different chemical contents of these steels and their joining methods may affect the mechanical properties and microstructure of the materials. In this study, AISI 1020-ASTM A514 steels have been welded by MMAW (MMAW manual metal arc welding), MIG (MIG-metal inert gas), MAG (MAG-metal arc gas) and TIG (TIG-tungsten inert gas) welding. Tensile tests, bending tests and hardness measurements have been carried out. The material microstructure has been investigated by means of optical microscopy in order to characterize the effect of processing parameters on the joints quality. The highest tensile strength and hardness values have been obtained for the MAG welded couples, while the lowest values have been obtained for the TIG welded materials. These changes have been explained with reference to the microstructure changes.Öğe Effect of Mechanical Properties of AISI 1018 Steel Surface Coating Stellite 6 by GTA Method(Düzce Üniversitesi, 2013) Apay, Serkan; Gülenç, BehçetMetal technology, surface coating operationsplays an important role. The purpose of surface coating operations, modification ofthe covered surface, improve the mechanical propertiesof the surface low, even develop. In this study, Tungsten Inert Gas (TIG) welding method and cobalt-based alloy produced by Deloro Stellite Group Stellite 6 wire made of low-carbon coatingon the surface of AISI 1018 steel. As a result ofthecoating process, the coated surface microstructures examined sections. Scanningelectron microscopy (SEM) images taken, and energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analyzes were conducted. Map of the line element analysis method and analysis covering Stellite 6 alloy, cobalt chrome and diffusion of AISI 1018 steel was investigated. Micro-hardness measurements and wear tests were carried out as a mechanical test specimens.Öğe The effect of shielding gas on weldability of the AISI 420 martensitic stainless steel(Walter De Gruyter Gmbh, 2023) Acar, İsmail; Çevik, Bekir; Gülenç, BehçetMost of weld defects occurring in the welding of martensitic stainless steels are caused by the presence of hydrogen. Thus, the effects of hydrogen in the weld zone need to be well-understood to estimate the quality and service life of martensitic stainless steel joints. In the present study, AISI 420 martensitic stainless steel materials were welded by using different combinations of shielding gas via the gas metal arc welding (GMAW) method. It is known that shielding gases also play a critical role in heat input, cooling rate, microstructure of weld seam, weld defects, and mechanical properties besides drying of molten weld pool. Thus, it is important to investigate the effects of shielding gases and gas combinations on the welding of martensitic stainless steels in the welding process. In the present study, 100 % Ar, 97 % Ar + 3 % H-2 and 93 % Ar + 7 % H-2 gas combinations were employed. The welded sheets were subjected to the metallographic examination as well as hardness, tensile, and bending tests. The effect of the tests and the combination of shielding gas on the mechanical and microstructural properties of AISI 420 stainless steel was investigated. The results indicated that a noticeable grain coarsening occurred in the microstructure of the weld metal and heat affected zones (HAZs) after the addition of H-2 into the Ar gas during the welding process. The highest tensile strength was obtained from the joints with 100 % Ar gas. As a result of the tensile test, rupture occurred in the base metal-HAZ transition zone in all the welded samples. In the joints welded with 97 % Ar + 3 % H-2 and 93 % Ar + 7 % H-2 gas combinations, fracture occurred in the base metal-HAZ transition zone during the bending test.Öğe Effect of tool material on microstructure and mechanical properties in friction stir welding(Carl Hanser Verlag, 2016) Çevik, Bekir; Özçatalbaş, Yusuf; Gülenç, BehçetAlthough the number of experimental studies investigating the effect of friction stir welding (FSW) parameters on joining properties have increased recently, there are not sufficient numbers of studies on the effect of the stirring tool material in friction stir welding. This study investigated the effect of stirring tool materials on microstructure, mechanical properties and residual stress of joints. Samples of 7075-T651 Al alloys were joined by FSW using uncoated and TiN-coated X210Cr12 alloy steel stirring tools. The welding processes were performed at rotational speeds of 900, 1250 and 1600 rpm and at a welding speed of 60 mm x min(-1). Mechanical and metallographic tests were applied to the welded joints and residual stress analysis was performed using the hole drilling method. The best mechanical properties were determined in the welded samples joined by the uncoated tool at a rotational speed of 900 rpm. It was also determined that the TiN-coated tool negatively affected the mechanical and metallurgical properties of the weldements. Moreover, the highest longitudinal residual stresses were specified in the joining performed by the uncoated tool.Öğe The effect of welding speed on mechanical and microstructural properties of 5754 Al (AlMg3) alloy joined by laser welding(Iop Publishing Ltd, 2018) Çevik, Bekir; Gülenç, Behçet5754 (AlMg3) alloys have advantages such as good strength, perfect corrosion resistance and cold forming in addition to the low specific density. Because of these advantages, they are commonly used in automotive, chemical and food industries, and especially in the vessel and yacht industry. However, in spite of having such important and common areas of usage, it is very difficult to join Al and its alloys by traditional welding methods. This study focused on joining of 5754 Al alloy materials, which are hard to be joined by the traditional welding methods but have common areas of usage, by using the laser welding method. Laser welding method has many advantages such as the low heat input, deep penetration, low residual stress, and distortion compared to traditional welding methods. For this purpose, 3 mm thick 5754 Al alloy sheets were joined by using the laser welding method. The welding processes was carried out selecting three welding speeds (3, 4.8, and 6 m min(-1)). The macrostructure, microstructure, hardness, tensile, and impact strength properties of the samples taken from the welded joints were examined. It was observed that micro-porosity and micro-void defects formed in the microstructure of the weld metal. The rate and size of these defects increased with increasing welding speed. The increase in the welding speed decreased the amount of the accumulated metal and the penetration rate. The mechanical properties were also negatively affected by the increase in the welding speed.Öğe Effect of welding speed on the mechanical properties and weld defects of 7075 Al alloy joined by FSW(Redakcia Kovove Materialy, 2016) Çevik, Bekir; Özçatalbaş, Yusuf; Gülenç, BehçetIn this study, 7075-T651 Al alloys were joined by friction stir welding (FSW) at a fixed rotational speed and different welding speeds. The stirring tool used in the welding processes was comprised of a shoulder of 20 mm in diameter and modified M6 x 1 HSS hand taps used as pins. The FSW was performed at a rotational speed of 1600 rpm and at welding speeds of 20, 40, and 60 mm min(-1). Mechanical and metallographic tests were carried out on the welded joints and the effects of the welding speed on the mechanical and metallurgical properties of the welded specimens were investigated. Welding speed significantly affected the microstructure and mechanical properties of the joining. Results showed that the average grain size of the weld nugget was reduced as welding speed was increased. In addition, it was found that high welding speed negatively affected the mechanical properties of the weld nugget.Öğe The Effects of Critical Welding Parameters on Tensile-Shear Properties of Friction Stir Spot Welded Polyethylene(Gazi Univ, 2017) Çevik, Bekir; Gülenç, Behçet; Durgutlu, AhmetThe aim of this study was to investigate the weldability of high density polyethylene via friction stir spot welding method. Polyethylene sheets were joined with dwell times of 60 to 100 s, three different pin profiles (M6x1, M6x1.25, M6x1.5) and pin lengths of 3.75 to 4.75 mm by using rotational speed of 900 rpm and delay time of 45 s. During welding processes, the temperatures were measured under the welding centers. The tensile-shear tests were performed to welded samples. Also, macrostructures of welding nuggets were examined. The small welding nuggets were formed by using the lower dwell time. The melting in welding nugget occurred in the all dwell times during the welding. The dwell time affected on the friction temperature. The key (pin) hole closed when sufficient friction temperature (dwell times of 80 and 100 s). The pin profiles directly affected the welding quality. Large screw pitch range of the pin and the small pin length from 4.5 mm negatively affected the weld fracture load. Pin length of the stirring tool directly affected the quality of welding.Öğe Friction Stir Welding of 7075-T651 Aluminium Alloy(Carl Hanser Verlag, 2016) Çevik, Bekir; Özçatalbaş, Yusuf; Gülenç, BehçetThe microstructural changes, mechanical properties and residual stress distribution of 7075-T651 Al alloy joined using friction stir welding were investigated in this study. Welding was performed at 900, 1 250, and 1 600 rev/min and 20, 40, and 60 mm/min welding speeds. Mechanical tests were carried out on the welded joints in addition to microstructural examinations performed using a scanning electron microscope. Furthermore, residual stress distribution of the joints was determined by the hole drilling method. Generally, higher tensile strength was obtained at medium rotational and welding speeds. Tunnel defects were formed in the root of the weld seam. At high welding speeds, insufficient filling in the joints led to microvoids and large grain bands on the retreating side of the weld seam. The tensile strength of the welded specimens decreased at the rate of 26-45 % compared to the reference material. Lower residual stresses were determined in the specimens joined at a high rotational speed.Öğe Microstructural evolution and weldability of AISI 4042 steel(Trans Tech Publications Ltd, 2011) Gülenç, Behçet; Uygur, İlyas; Bayram, İsmail; Durgutlu, Ahmet; Kap, TuncayHigh carbon content and addition of other elements, such as Mn in steel, causes some difficulties in the weldability of these materials. In this study, pre and post heating processes were applied for the multipass welded specimens. Tensile test, notch impact test and hardness measurements were carried out, and microstructural features were examined. The weldability of these steels can be improved with the pre and post heat treatments. Maximum hardness values were obtained for the non-heat treated specimens due to large grain structure and high volume percentage of the pearlite content. Although applied heat treatments caused decrease in hardness values, an increase in tensile properties and toughness values at all temperatures occurred. Changes in these properties were explained in the light of the microstructure of the AISI 4042 steel specimens.Öğe Wear properties of AISI 1015 steel coated with Stellite 6 by microlaser welding(Elsevier Ltd, 2014) Apay, Serkan; Gülenç, BehçetSurface coating operations have an important place in metal technologies. The aim of surface coating operations is to improve and enhance the inferior properties of a surface through its modification. In this study, low-carbon AISI 1015 steel was coated with cobalt-base alloy Stellite 6 welding wire by microlaser welding. After coating, the microstructures of the coated surface cross-sections were examined. The microstructure, hardness and wear resistance of the surface-alloyed layer were investigated using optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction analysis, and Vickers hardness (HV0.1) and pin-on-disk tests. The chrome and cobalt diffusion from the Stellite coating alloy to the AISI 1015 steel was examined by means of the line analysis method and element mapping analyses. The results obtained from the tests were interpreted and supported by comparison with tests conducted in similar studies reported in the literature. © 2013 Elsevier Ltd.
