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Öğe Casting properties of ASTM A128 Gr. E1 steel modified with Mn-alloying and titanium ladle treatment(Springer Singapore Pte Ltd, 2021) Gurol, Ugur; Karadeniz, Erdal; Coban, Ozan; Kurnaz, Suleyman CanThis work aims to produce a high manganese steel with more refined austenite grains and better wear resistance without sacrificing the toughness and tensile properties by Mn alloying and Ti ladle treatment in comparision to ASTM A128 Gr. E1 steel (1.0C-13Mn) that is mostly used in the mining industry. The 1.0C-17Mn-xTi alloys (x=0, 0.05 and 0.1, in wt.%) were prepared. A relationship was established between the microstructures and mechanical properties of the as-cast and solution annealed alloys. Increasing Ti content increases the stable Ti(CN) phase on and beside the grain boundaries and decreases up to 37% the austenite grain size of the as-cast alloy with 0.10wt.% Ti. Correspondingly, after solution annealed, optimized titanium content (0.05wt.%) results in significant improvements in wear resistance, hardness, elongation, yield and tensile strengths by 44%, 31%, 30%, 8% and 12%, respectively, except 9% decrease in impact toughness compared to ASTM A 128 Gr. E1 steel without modification. These results show that 1.0C-17Mn-0.05Ti alloy can be used for parts exposed to high load wear and applied in conditions where relatively high tensile properties with sufficent ductility is needed.Öğe Characterization of Armour Steel Welds Using Austenitic and Ferritic Filler Metals(Springer India, 2022) Gurol, Ugur; Karahan, Tuba; Erdol, Sevim; Coban, Ozan; Baykal, Hakan; Kocak, MustafaIn this study, fillet welding processes were performed on high strength Miilux Protection 500 (MIL-A-46100) steel, which is used as armour material in defence industry, using GMAW method with austenitic ER307 and ferritic ER110S-G filler metals. The characterization of welded structure was carried out by performing elemental mapping processes as well as microstructural examination and microhardness tests. Results showed that hardness of weld metal was found to be 46% and 78% of the base metal hardness for austenic and ferritic filler metal, respectively. The fine-grained heat-affected zone was found to be the highest hardness while intercrital heat-affected zone was found to be lowest hardness through heat-affected zone. The smoother decrease was obtained in the softening zone with austenitic filler metal due to lower thermal conductivity. Consequently, the hardness values at a distance of 6 mm from the plate edge for both filler metals reached the hardness of base metal and both welded structures met the minimum requirements of the military standards.Öğe Characterization of Fillet Welded Armor Steel Performed by Robotic Gas Metal Arc Welding: Effect of Heat Input on Microstructure and Microhardness(Springer, 2023) Coban, Ozan; Kaymak, Fatih; Gurol, Ugur; Kocak, MustafaIn this research, fillet welding was conducted on 8-mm thick Miilux OY Protection 600 (MIL-A-46100) armor steel using AWS A5.9 GeKa ER307 austenitic filler wire. The welding process involved robotic MIG/MAG with five different heat inputs ranging from 0.3 to 1.2 kJ/mm. The study focused on examining the influence of heat input on the microstructure, elemental changes, microhardness, and dimensions of the weld metal and the heat-affected zone (HAZ). These investigations were conducted to determine the welding parameters that they satisfy the quality requirements of the MIL-STD-1185 standard for this steel grade and weld consumable. Through analysis of macrostructure, microstructure, and microhardness, it was observed that increasing the heat input led to a decrease in hardness for both the weld metal and the HAZ, while expanding the HAZ width. The weld metal exhibited a homogenous hardness distribution at lower and higher heat inputs, but hardness increased from the root to the face for both heat inputs of 0.5 and 0.7 kJ/mm welds. Notably, a significant decrease in hardness occurred in the transition of partial transformation region (intercritical HAZ) and tempering region (subcritical HAZ) for heat inputs above 0.7 kJ/mm, indicating softening. Moreover, the width of the subcritical heat-affected zone substantially increased. Evaluation of the distance required to reach base metal hardness from the welding toe revealed that a heat input of 1.2 kJ/mm exceeded the maximum requirement of 15.9 mm according to the MIL-STD-1185 standard. However, the requirements of the military standard were satisfied for other heat input values. These findings were associated with microstructural changes in grain size, martensite, bainite, martensite/austenite morphology and their fractions, as well as delta ferrite morphology. The results successfully demonstrated that robotic GMAW welding can be applied using lower strength (undermatched) filler metal to satisfy the requirements of the respective standard of MIL-STD-1185.Öğe Combustion Synthesis of B4C-TiB2 Nanocomposite Powder: Effect of Mg Particle Size on SHS and Optimization of Acid Leaching Process(Pleiades Publishing Inc, 2023) Coban, Ozan; Bugdayci, Mehmet; Baslayici, Serkan; Acma, M. ErcanIn this study, composite nanoparticles of B4C-TiB2 were produced by combustion synthesis. Production was carried out by self-propagating high-temperature synthesis (SHS) method in atmospheric conditions by using oxide raw materials (B2O3, TiO2), carbon black and magnesium as a reducing agent. The effect of Mg particle size on SHS efficiency was investigated. Single-stage and 2-stage leaching processes were carried out to remove undesired phases in the SHS product. In the 1st HCl acid leaching process, the leaching temperature and leaching duration were optimized. As a result of the 2nd leaching process with the addition of carbonic acid and H2O2, commercial quality nanoparticle synthesis was performed. Results revealed that the increase in Mg particle size decreased the SHS efficiency, however very fine particle sized Mg usage decreased the SHS efficiency due to the evaporation and scatter of Mg. The optimum Mg particle size was determined as 75-150 mu m. Since it has a significant effect on the removal of Mg-borate phases, 90 degrees C was determined as the optimum leaching temperature. The optimum leaching duration was determined to be 60 min. As a result of optimized leaching processes, 99.11% purity B4C-TiB2 nanoparticle with 193.5 nm particle size and 30.65 m(2)/g surface area was synthesized.Öğe Effect of Mg stoichiometry on self-propagating high temperature synthesis (SHS) of ZrC nanoparticles in ZrO2-Mg-C system(Taylor & Francis Ltd, 2023) Bugdayci, Mehmet; Coban, Ozan; Baslayici, SerkanIt is significant to develop the production processes of Zirconium Carbide (ZrC) nanoparticles due to its superior properties. In this study, self-propagating high-temperature synthesis (SHS) followed by an acid leaching route was used to produce ZrC powder. ZrO2 was used as the zirconium source, C black as the carbon source and Mg as reductant. After modelling thermodynamically with the FactSage 7.1 software in terms of adiabatic temperature and possible phases, SHS processes were carried out with varying reductant stoichiometry (90%, 100%, 110%, 120%) and applying chemical treatment with HCl leaching for purification. The obtained products were characterised by XRD and SEM-EDS analysis. The optimum reductant stoichiometry for the production of ZrC was determined as 110%. As a result of the leaching processes, it was revealed that ZrC powders with an average particle size of 320 nm and containing a small amount of oxide residues could be synthesised. Compared to carbothermal reduction, which is the main production method of the material, the desired compounds were synthesised with much lower energy consumption and in much finer particles.Öğe Effect of the notch location on the Charpy-V toughness results for robotic flux-cored arc welded multipass joints(Walter De Gruyter Gmbh, 2022) Gurol, Ugur; Coban, Ozan; Cosar, Ibrahim Can; Kocak, MustafaIn this study, the effect of the notch locations on the Charpy-V toughness values of the all-welded joint obtained using robotic flux-cored arc welding was investigated with respect to microstructures at the notch locations. Charpy impact tests were performed through the thickness with notch location at the centerline as well as off-set regions of the weld metal in addition to the microhardness measurements conducted. The detailed weld metal characterization was conducted using a stereo microscope, optical microscope, and scanning electron microscope at the same location where the Charpy tests and microhardness tests were performed. The sub-zero impact toughness test results indicated that the columnar weld metal regions exhibited low toughness values while the centerline microstructure consisting of mainly reheated regions displayed much higher toughness values even at the test temperature of -60 degrees C, satisfying the toughness requirement of the requested 47 J value. It is concluded that a small variation of the through-thickness notch position may result in different toughness values for the same weld metal. On this basis, the notching procedure of the Charpy-V samples for the multi-pass weld metal should be conducted with care and obtained results should be explained with respective notch position and microstructure.Öğe FRICTION STIR BUTT WELDABILITY OF DISSIMILAR ALLOYS AA5754 AND AA1050(World Scientific Publ Co Pte Ltd, 2023) Karagoz, Idris; Cakir, Recep; Coban, Ozan; Boumerzoug, ZakariaThe main objective of this study was to assemble by friction stir welding two dissimilar sheets made with AA5754 Al-Mg alloy and AA 1050 aluminum, which are intensely used in the automotive industry. The applied welding speed was 75mm/min with different tool rotational speeds (780, 1330 and 2440rpm). The mechanical properties and the microstructure of the welded joint were investigated by the tensile test, the three-point bending test, the microhardness measurements, the optical microscopy, scanning electron microscopy and energy dispersion spectrometry (EDS). The main zones were observed in the welded joint. Optimum mixing was achieved during the assembly process with a welding tool rotation speed of 2440rpm. It was determined that the microstructures formed had a significant effect on the hardness and tensile strength of welded dissimilar materials such as the precipitated phases in the nugget zone. The best result in terms of tensile strength was obtained at 780rpm with 80% performance.Öğe HYDROMETALLURGICAL NICKEL AND COBALT PRODUCTION FROM LATERITIC ORES: OPTIMIZATION AND COMPARISON OF ATMOSPHERIC PRESSURE LEACHING AND PUG-ROAST-LEACHING PROCESSES(Scicell Sro, 2021) Coban, Ozan; Baslayici, Serkan; Bugdayci, Mehmet; Acma, Mahmut ErcanCorresponding to the technological developments, production and consumption of nickel have increased greatly over time due to its unique mechanical and chemical properties. Therefore, the production of nickel will always keep its importance. The availability of laterite ores, which are oxide type ores, is 86% of the nickel reserves on the Earth, and the processes used in the production of nickel from sulphide type ores have negative environmental effects. Therefore, recovery of nickel from lateritic ores has become increasingly important in recent years. In this study, the aim was to determine the optimum parameters of nickel and cobalt production from limonite type lateritic nickel ores, which were taken from Manisa Caldag region of Turkey, using atmospheric pressure sulfuric acid leaching and pug-roast-leach process. When the results obtained in these processes were compared, it was found that the Ni leaching efficiency is nearly 8% higher and iron leaching efficiency (contamination) is nearly 4% lower in the pug-roastleach process. Furthermore, the pug-roast-leach process was completed in 33% lower time compared to the atmospheric pressure sulfuric acid leaching process.Öğe Production of B4C-TiB2 composite powder by self-propagating high-temperature synthesis(Springer, 2022) Coban, Ozan; Bugdayci, Mehmet; Acma, M. ErcanAdvanced ceramics find significant application areas due to their superior mechanical, electrical, magnetic chemical and thermal properties. By combining these materials, significant properties can be obtained as a result of production of the composites of hard metal compounds in nanoscale dimensions. Self-propagated high-temperature synthesis (SHS) is one of the prominent methods for the production of such nanoparticles. SHS is a combustion synthesis method. In this study, nanocomposite powders of B4C-TiB2 were synthesized by SHS method. FactSage software was used for thermochemical simulation and computational stoichiometric optimization. In the experimental step, 2 different SHS sets were prepared. In the first stage, B4C and TiB2 powders were synthesized. The B4C-TiB2 composite was produced in the final set of experiments. Then, production parameters of B4C-TiB2 composite powders, from B2O3, TiO2, and carbon black, were investigated. Magnesium powder was used as reductant agent. Afterwards, HCl leaching process was performed, and acid concentration was optimized. The effect of carbonic acid and H2O2 addition on dissolution of undesired phases was also been investigated as a new method. Products were characterized by XRD, SEM and BET analysis. B4C-TiB2 composite powder with quite high surface area, fine particle size and high porosity could be synthesized with reasonable purity. According to the results, the optimum molar ratios were determined as TiO2:B2O3:Mg:C = 1:3:12:1.6. Optimum acid concentration was found to be 10.5 M for leaching process, and carbonic acid addition on leaching step found to be effective on TiO2 removal. The highest purity could be obtained with 50%-50% stoichiometry. It has also been determined that the synthesis of B4C-TiB2 composite powder has a positive effect on both the chemical content and the morphology that will increase the sintering ability.