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Öğe Ca and Ce Effect on the Corrosion Resistance of Hot-Rolled AZ31 Mg Alloys(Dr D. Pylarinos, 2020) Kara, I.H.; Ahlatci, H.; Issa, Yousef, T.A.; Turen, Y.In this study, AZ31 Mg alloys with added Ca and Ce were produced by low pressure die casting and were rolled at 400°C. The corrosion properties of the materials were determined by immersion test for 72 hours at a 3.5% NaCl solution. The microstructure of the samples was investigated by light optical microscopy (LOM) and scanning electron microscopy (SEM) before the corrosion test. Twins, dynamic recrystallization (DRX), and the alloying elements have an important role in imparting the final corrosion resistance of the investigated materials. © 2020, Dr D. Pylarinos. All rights reserved.Öğe Characterization and Reduction Behavior of Cold-Bonded Composite Pellets for Direct Reduction Using an Organic Binder(Springer, 2013) Cevik, E.; Ahlatci, H.; Sun, Y.The purpose of this study was to investigate the reduction behavior of cold-bonded composite pellets produced from low-grade hematite iron ore using molasses solution at various concentrations, as well as their physical and chemical properties. Direct-Reduction Iron (DRI) technology makes it possible to assess low-grade iron ores and convert them into scrap at facilities that have electric arc furnaces. The reductant used was coke with fixed carbon of 86.04%. The alkalinity rate was adjusted to 0.7 by adding calcium carbonate. In the composite pellets produced, the 300 N/pellet compression strength recommended in the literature was achieved with a Fe-tot/C-fix ratio of 2.5 and 3 using a 50% concentrated molasses solution. Composite pellets prepared with a Fe-tot/C-fix ratio of 3.5 using a 40% concentrated molasses solution reached a compression strength of 496 N/pellet. The porosity is inversely proportional to the increase in compression strength and binder concentration. Reduction experiments were conducted by applying different temperatures and durations to samples possessing optimum conditions for each Fe-tot/C-fix ratio: the best result was achieved with a 88% reduction rate in composite pellets with a Fe-tot/C-fix ratio of 3.5 at the end of 1 h. Pig iron nuggets were characterized using an optical microscopy (LOM) and a scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS).Öğe Corrosion resistance of powder injection moulded titanium in physiologic serum and artificial saliva(Chinese Acad Sciences, Inst Metal Research, 2010) Candan, S.; Turkmen, M.; Ahlatci, H.; Candan, E.Most of dental implants are made from titanium or titanium based alloys. However, one of the drawback of such implants is high cost due to the technological difficulties in casting method or machining. In this work, powder injection moulding (PIM) method has been used in order to explore lower cost implants without minimising the biocorrosion resistance of the titanium. Corrosion resistance of titanium specimens, produced by powder injection moulding method (PIM-Ti), in physiologic serum and artificial saliva was investigated. Commercially pure bulk Ti (CP-Ti) was used as control sample. Surface oxidation was also carried out to both PIM-Ti and CP-Ti samples. Microstructure and corrosion resistance were investigated using microhardness, X-ray diffraction (XRD), scanning electron microscopy (SEM) and potentiodynamic polarization experiments. Resulting microstructure of PIM-Ti samples contained porosity as compared to CP-Ti control samples. Microhardness of PIM-Ti samples varied with varying applied load whereas it was free from applied load for CP-Ti control samples. Polarisation measurements and SEM analysis revealed that corrosion behaviour of PIM-Ti was reasonably as good as CP-Ti both in as-produced and oxidized conditions in physiologic serum and artificial saliva in spite of its porous structure.Öğe Corrosion resistance of powder injection moulded titanium in physiologic serum and artificial saliva(2010) Candan, S.; Turkmen, M.; Ahlatci, H.; Candan, E.Most of dental implants are made from titanium or titanium based alloys. How- ever, one of the drawback of such implants is high cost due to the technological di°culties in casting method or machining. In this work, powder injection moulding (PIM) method has been used in order to explore lower cost implants without min- imising the biocorrosion resistance of the titanium. Corrosion resistance of titanium specimens, produced by powder injection moulding method (PIM-Ti), in physiologic serum and artificial saliva was investigated. Commercially pure bulk Ti (CP-Ti) was used as control sample. Surface oxidation was also carried out to both PIM- Ti and CP-Ti samples. Microstructure and corrosion resistance were investigated using microhardness, X-ray diffraction (XRD), scanning electron microscopy (SEM) and potentiodynamic polarization experiments. Resulting microstructure of PIM-Ti samples contained porosity as compared to CP-Ti control samples. Microhardness of PIM-Ti samples varied with varying applied load whereas it was free from applied load for CP-Ti control samples. Polarisation measurements and SEM analysis re- vealed that corrosion behaviour of PIM-Ti was reasonably as good as CP-Ti both in as-produced and oxidized conditions in physiologic serum and artificial saliva in spite of its porous structure.Öğe Dry sliding wear behaviour of Fe-0.4C-25Cr-XNi cast steels(Elsevier Science Sa, 2006) Sun, Y.; Ahlatci, H.; Ozdogru, E.; Cimenoglu, H.The effect of composition and heat treatment (solutionizing at 1200 degrees C and aging at 750 degrees C) on the room temperature mechanical properties (hardness and impact toughness) and dry sliding wear resistance of Fe-0.4C-25Cr-XNi steels (where nominal Ni contents were 4, 12 and 20 wt.%) have been investigated. The steel containing 4 wt.% Ni had ferritic and others (12 and 20 wt.% Ni) had austenitic matrixes along with M23C6 type chromium carbides. The applied heat treatment resulted in precipitation of sigma phase in austenitic matrix, which was accompanied by an improvement in hardness and a decrease in impact toughness. Ferritic matrix steel exhibited higher hardness and lower impact toughness than austenitic matrix steels. The results of the wear tests conducted on an unlubricated M2 quality tool steel disc revealed that at test pressures lower than 2.2 N/mm(2), the dominant wear mechanism was mild wear. However, at high test pressures (> 2.2 N/mm(2)) severe wear mechanism was operative. Increase of hardness and decrease of toughness resulted in a decrease in wear resistance under mild wear conditions. However, these mechanical properties were not effective on wear resistance under severe wear testing conditions. (c) 2005 Elsevier B.V. All rights reserved.Öğe Effect of Ca and Ce on Wear Behavior of Hot-Rolled AZ31 Mg Alloys(Polish Acad Sciences Inst Physics, 2020) Kara, I. H.; Yousef, T. A. I.; Ahlatci, H.; Turen, Y.In this study, Ca and Ce added AZ31 Mg alloys were produced by low pressure die casting method and the following materials were rolled at 400 degrees C. The wear properties of materials were investigated by wear test method according to ASTM-G133 in a dry condition at room temperature. The microstructure of samples investigated by light optical microscopy and scanning electron microscopy both before and after corrosion tests. The twins and dynamic recrystallization (DRX) and the alloying elements play an important role to impart the final wear resistance of investigated materials.Öğe Effect of copper addition on wear and corrosion behaviours of Mg2Si particle reinforced composites(Elsevier Sci Ltd, 2012) Palta, A.; Sun, Y.; Ahlatci, H.The purpose of this study is to investigate the effect adding Cu has on the wear and corrosion properties of in situ'' Mg2Si particle reinforced Al-12Si-20Mg matrix composites, produced with help of the nucleation and growth of the reinforcement from the source matrix, in order to overcome the disadvantages of composites produced by externally reinforcing ceramic particles. Composites known as Al-12Si-20Mg-XCu were produced by adding Cu, at the rate of 1%, 2%, and 4%, to the Al-12Si-20Mg alloy in order to achieve this purpose. The microstructural characterisation, hardness, wear and corrosion properties of composites, produced using the casting method, were analysed. Dry environment wear experiments for investigated alloys were conducted using a pin-on-disc type wear device under different loads and at different sliding distances. The change in weight loss of the solution containing 30 g/l NaCl + 10 ml/l HCl, and the tafel extrapolation method were used to analyse corrosion behaviour. Results of microstructural characterisation concluded that as the amount of Cu added to the Al-12Si-20Mg alloy increased, the size and volume of the Mg2Si particle, formed within the matrix, decreased, and CuAl2 intermetallics formed within the matrix. Results of wear experiments concluded that adding Cu developed wear resistance under small loads; however, reduced wear resistance under high loads. According to results of corrosion experiment, corrosion resistance increased with the addition of Cu. (C) 2011 Elsevier Ltd. All rights reserved.Öğe Effect of indium addition on microstructure and mechanical properties of AS-CAST and hot-rolled AM60 magnesium alloy(TANGER Ltd., 2017) Zengin, H.; Turen, Y.; Ahlatci, H.; Sun, Y.In this study, effect of indium (In) addition on microstructure and mechanical properties of AM60 magnesium alloys was investigated. In additions were made by 0.2, 0.5 and 1 wt.%. Alloys were produced by conventional gravity casting in a steel mould. A homogenization treatment at 350 °C for 24 h was performed after casting processes. Homogenized samples were 1 pass hot-rolled by 40 % thickness reduction at 350 °C. The results showed that the average grain size of as-cast and hot-rolled AM60 alloys decreased with In addition. SEM analysis revealed that In addition led to formation of tiny Mg-In binary second phases at triple junctions. Tensile strength of as-cast AM60 alloy increased with increasing amount of In up to 0.5 wt.% above which it decreased. However, after hot-rolling process, AM60 alloy containing 0.2 wt.% In showed the best tensile properties. These improvements were attributed to the refinement of microstructure and dispersion strengthening by Mg- In intermetallic phases. © 2017 TANGER Ltd., Ostrava.Öğe Effect of Lanthanum on the Microstructure and Mechanical Properties of Hot-Rolled Magnesium Alloy AZ31(Springer, 2019) Kara, I. H.; Ahlatci, H.; Turen, Y.; Sun, Y.The effect of lanthanum additions (0.2 - 1.0%) on the microstructure and mechanical properties of magnesium alloy AZ31 is studied after hot rolling with deformation of 15 and 30%. The microstructure is analyzed by the methods of x-ray diffractometry, optical microscopy and scanning electron microscopy. The mean values of the ultimate strength, elongation and contraction are determined in tensile tests.Öğe Effect of Magnesium Additions on Composites with Al and Al-12% Si Matrices Strengthened with B4C and Prepared by Infiltration Under Pressure(Springer, 2016) Cevik, E.; Sun, Y.; Ahlatci, H.; Turen, Y.Metallographic and x-ray phase analyses are used for metal-matrix composites Al - B4C and (Al - 12% Si) - B4C with a volume fraction of 60% boron carbide prepared by infiltrating a pressed workpiece with metal under pressure. It is shown that with introduction of 1 to 4% Mg into a metal matrix composite porosity is reduced from 7 to 1%.Öğe EFFECT OF PEAK-AGED HEAT TREATMENT ON CORROSION BEHAVIOR OF THE AA6063 ALLOY CONTAINING Al3Ti(Polska Akad Nauk, Polish Acad Sciences, Inst Metall & Mater Sci Pas, 2012) Cevik, E.; Sun, Y.; Ahlatci, H.The purpose of this study is to analyse the microstructure and corrosion properties of homogenised and aged AA 6063 aluminium alloys, containing up to 2% Ti, after the conventional casting technique. The microstructure of the homogenised and aged alloys was examined using an optic microscope, and scanning electron microscope. The micro-hardness test was used for the hardness measurements of the investigated alloys. Corrosion tests were performed by suspending samples of certain sizes into 30 gr/l NaCl + 10 ml/l HCl solutions, measuring the mass loss; potentiodynamic polarisation measurements were carried out in the same solution. The microstructure characterization of the investigated alloys shows the Al (matrix), non-shaped dark globular grey-coloured phase and rod-shaped phases formed at the grain boundaries. The non-shaped dark grey-coloured phase is Mg2Si. The rod-shaped phase, formed in the microstructure of the Ti-added AA 6063 alloys, is Al3Ti. The Ti content of the alloy increases, the Al3Ti phase tends to elongate and become plated. The results of the corrosion tests proved that the corrosion rate decreased in alloys containing less than 1% Ti, and the rate of corrosion increased in alloys containing more than 1% Ti, regardless of whether the alloys were homogenised and aged. Another observation was that aging heat treatment improved corrosion resistance.Öğe Effect of sn addition on corrosion properties of As-Cast and Hot-Rolled AZ31 magnesium alloys(Trans Tech Publications Ltd, 2017) Turen, Y.; Guzel, D.; Zengin, H.; Sun, Y.; Ahlatci, H.In this study, the effect of Sn addition on corrosion resistance of as-cast and hot rolled AZ31 magnesium alloy was investigated. Sn additions were made by 0.2 wt%, 0.5 wt% and 1 wt%. An electric resistance furnace was used to produce alloys. Hot rolling process was performed at 350 °C by 40% thickness reduction at one rolling pass. Microstructure characterizations were performed by optical (OM) and scanning electron microscope (SEM). Immersion tests and electrochemical analyses were performed to investigate the corrosion resistance of the alloys. A 3.5% NaCl working solution at room temperature was used in both corrosion tests. The results showed that Sn addition decreased the primary dentrite size and restricted the growth of secondary dentritic arm. The as-cast structures transformed to dynamically recrystallized grain structures after hot-rolling process in all the alloys. Corrosion resistance of AZ31 magnesium alloy tended to decrease with Sn addition. This decrease was more clear in homogenized and hot-rolled states while there were some flactuations in as-cast states. © 2017 Trans Tech Publications, Switzerland.Öğe Effect of the particle size on the mechanical properties of 60 vol.% SiCp reinforced Al matrix composites(Walter De Gruyter Gmbh, 2002) Ahlatci, H.; Candan, E.; Cimenoglu, H.The effect of the reinforcing particle size on the mechanical properties of 60 vol.% SiC reinforced aluminium matrix composites produced by the pressure infiltration technique was examined by compression, impact and wear tests. The compression strength and the impact resistance decreased with increasing reinforcing particle size. The composites exhibited different abrasion behaviour depending on the size of abrasive Al2O3 grains. On fine abrasive Al2O3 grains (85 mu m), the abrasion resistance increased with increasing reinforcing SiC particle size. The contrary result was obtained on coarse abrasive Al2O3 grains (250 mu m). The wear tests conducted on M2 quality tool steel revealed that reinforcing of aluminium with coarse SiC particles has a very beneficial effect on the wear resistance with respect to fine reinforcing SiC particles.Öğe Effect of Ti addition on corrosion properties of As-Cast and Hot-rolled AM60 magnesium alloys(Trans Tech Publications Ltd, 2017) Sun, Y.; Aydin, N.U.; Turen, Y.; Ahlatci, H.; Zengin, H.This study investigates the effect of Ti addition (0.2, 0.5, 1wt%) on corrosion resistance of as-cast and hot rolled AM60 magnesium alloy. The results showed that Ti addition resulted in an alteration of the microstructure of as-cast AM60 magnesium alloy by decreasing the amount of-Mg17Al12 eutectic phase. Homogenization treatment resulted in the dissolution of the most of the-Mg17Al12 phases. Corrosion behaviors were investigated by immersion tests and electrochemical analysis. Homogenized samples exhibited the lowest corrosion rate in immersion test while the best corrosion resistance was found for hot-rolled samples in electrochemical test. In hot-rolled state, Ti addition led to a slight change in the corrosion behaviour of AM60 magnesium alloy. © 2017 Trans Tech Publications, Switzerland.Öğe Effect of Ti on the Corrosion Behaviour of In-Situ Mg2Si Particle Reinforced Al-12Si-20Mg-XTi Alloys(Trans Tech Publications Ltd, 2010) Ahlatci, H.; Durmaz, A.; Balta, A.; Acarer, M.; Candan, E.In this study, corrosion behaviour of Al-12Si-20Mg-XTi alloys (Ti content varied between 0 and 4 wt.%) was investigated. Characterizations of the alloys were carried out by microstructural examinations and corrosion tests. Microstructural results showed that precipitation of the Mg2Si phases was observed in Al-12Si-20Mg-XTi alloy matrix as two different morphologies; i.e. as a polyhedral primary particle and as a chinese script. Upon addition of Ti, Al3Ti intermetallic precipitated in the alloy. Corrosion tests were carried out by immersing the alloys in 30 g/l NaCl+10 ml/l HCl solution. Evaluation of corrosion was determined by measuring weight loss for 24 hours and by potentiodynamic polarization tests. Corrosion resistance of the alloy was approximately constant with 1 wt % Ti addition whereas at higher additions, the corrosion rate increased.Öğe Effects of 1WT.% Ti, In, and Sn Additions on the Microstructure, Mechanical and Corrosion Properties of the As-Cast and Hot-Rolled AM60 Magnesium Alloys(Springer, 2019) Turen, Y. U.; Zengin, H.; Sun, Ya.; Ahlatci, H.; Unal, M.We study the influence of 1 wt.% Ti, In and Sn additions on the microstructure, mechanical properties and corrosion resistance of the as-cast and hot-rolled AM60 magnesium alloys. The analysis of microstructure was performed by using optical and scanning electron microscopes The phase composition of the alloys and grain sizes are analyzed. We also determine the ultimate strength, yield limit, relative elongation, and corrosion resistance of the alloys. The efficiency of alloying of AM60 alloy with titanium and tin (for the improvement of the mechanical characteristics) and with indium (for the improvement of corrosion resistance) is demonstrated.Öğe Effects of bismuth (bi) additions on microstructure and mechanical properties of AZ91 alloy(TANGER Ltd., 2015) Elen, L.; Zengin, H.; Turen, Y.; Turan, M.E.; Sun, Y.; Ahlatci, H.In this study, the effects of bismuth additions of 0.2, 0.5 and 1 wt% on microstructure and mechanical properties of AZ91 alloy were examined. A permanent mold casting procedure was carried out to produce the alloy billets under a mixed gas atmosphere of SF6 and CO2. Microstructural investigations showed that Mg3Bi2 intermetallic phases were formed in all the samples and it coarsened with increasing amount of Bi in AZ91 alloy. Furthermore, a finer dispersion of Mg17Al12 intermetallic phases was observed in the structures as the amount of Bi in AZ91 increased. It was also showed that increasing Bi addition increased the hardness of AZ91 alloy. However, the highest hardness value was found for the alloy having 0.5wt% Bi addition that means high amount of Bi can decrease the hardness of AZ91 alloy. On the other, there were no considerable changes in the tensile strengths and yield strengths of the alloys as the amount of Bi increased although a slight increase in both strengths were observed with increasing amount of Bi. Percent elongation at break showed a decrease as Bi addition increased.Öğe The Immersion Corrosion Resistance of Shot Peening and MAO Applied on AZ31?0.5% La Sheets(Dr D. Pylarinos, 2020) Elmansouri, G.; Ahlatci, H.; Kara, I.H.; Turen, Y.In this study, the effect of Shot Peening (SP) and Micro Arc Oxidation (MAO) process on the corrosion resistance of 0.5% La with added AZ31 Mg alloy, hot rolled at different rolling speeds, was investigated. It was found that the surface of the rolled material at a rolling speed of 4.7m/min had higher surface smoothness values than the one rolled at 10m/min. It was observed that the corrosion rate changed in the first 40 of 168 hours. In the following hours, the corrosion rate showed different results according to the initial microstructure properties of the base materials. Initially, pore size was the dominant factor determining corrosion resistance, although, after coating, the corrosion rate was affected by the twins formed, based on rolling speed, which enhanced the corrosion rate between 48 and 168 hours. © 2020, Dr D. Pylarinos. All rights reserved.Öğe Investigation of corrosion properties of box boring din 20MnCr5 steel bars(EDP Sciences, 2023) Sahin, N.; Isikgül, A.; Ziyamukhamedova, U.; Ahlatci, H.; Acarer, M.; Sevim, M.In this study, boriding process was carried out on ? 11 mm diameter DIN 20MnCr5 quality steel bars, used in chain elements such as links and rings, and fasteners such as bolts, at 950oC boronizing temperature, boriding times of 2.5 and 7.5 hours. In this study, the formation and growth of the boride layer and the metallographic structure, the coating thickness and corrosion properties of the boronized steels were investigated depending on the boriding conditions. In the box boriding process, Ekabor-II powder mixture, with its commercial name, was used as boriding powder. According to the optical microstructure results made as a result of box boriding, the coating thickness was 371.5 ?m in the ? 11 mm diameter boronized DIN 20MnCr5 steel bar for 7.5 hours boriding times while it was 195.6 ?m in that steel bar for 2.5 hours boriding times. Corrosion experiments were carried out in solutions prepared by adding 3.5% NaCl to distilled water. According to the results of the immersion test, the lowest corrosion rate in mdd was measured as 112 mg/(dm2 x day) in the ? 11 mm diameter, 7.5 hour boronized sample, and the highest corrosion rate in mdd was 1456.75 mg/(dm2 x day) in the untreated ? 11mm diameter sample. In the potentiodynamic polarization test, parallel results were obtained for immersion corrosion. Corrosion rate values (icor) were measured at the highest value of 209 x 10- 6 A/cm2 in the untreated ? 11 diameter sample, while the lowest icor value was 0.0039 x 10- 6 A/cm2 in the ? 11 mm diameter sample borided for 7.5 hours. © 2023 EDP Sciences. All rights reserved.Öğe INVESTIGATION OF MECHANICAL PROPERTIES OF ACCELERATED COOLED AND SELF-TEMPERED H-TYPE STRUCTURAL SECTIONS(Polska Akad Nauk, Polish Acad Sciences, Inst Metall & Mater Sci Pas, 2023) Isikgul, A.; Ahlatci, H.; Esen, I.; Turen, Y.; Yagiz, O.This study investigates mechanical properties of accelerated cooled and self-tempered (AC-ST) H-type S275JR quality steel sections in HEA120 and HEB120 sizes. The cooling process is conducted with a specially manufactured system that sprays a coolant consisting of a water + compressed air mixture on the section surfaces. Cooling times were applied as 10 and 30 seconds using 4 and 12 bar compressed air + water at an average constant pressure of 5 bar and a constant flow rate of 0.08 kg/s. In the HEA120 sections, the highest cooling rate was obtained with 83 degrees C/s in the web region under the cooling time of 30 s and the air pressure cooling condition of 12 bar. At the cooling rate up to 6 degrees C/s, the microstructure is transformed to acicular ferrite and polygonal ferrite phase from Ferrite+Pearlite. But upper bainite phase was formed at a cooling rate of 30 degrees C/s, and a small amount of martensite and lower bainite microstructures were observed at a cooling rate of 60 degrees C/s and above. The hardness in the untreated sections, in the range of 106-120 HB, was increased to 195 HB at a cooling rate of 83 C/s in the web region of the HEA120 section. For a cooling rate of 23 degrees C/s, the maximum compressive residual stresses of -352 MPa are measured in the crotch region of the HEB120. And for a cooling rate of 6 degrees C/s, the maximum tensile residual stresses of 442 MPa were determined in the flange region of the HEA120 section.
