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Öğe Ca and Ce Effect on the Corrosion Resistance of Hot-Rolled AZ31 Mg Alloys(Eos Assoc, 2020) Kara, Ismail Hakki; Yousef, Taher Ali Issa; Ahlatci, Hayrettin; Turen, YunusIn this study, AZ31 Mg alloys with added Ca and Ce were produced by low pressure die casting and were rolled at 400 degrees 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.Öğe Corrosion Resistance of Interstitial Free Steel and Mg Alloys Sheets Joined by Mechanical Clinching(Springer, 2023) Mhawesh, Ziadoon Tareq; Kara, Ismail Hakki; Zeyveli, MetinThe corrosion resistance of mechanically clinched interstitial free (IF) steel-Mg joints was investigated by potentiodynamic and immersion corrosion tests in 3.5% NaCl solution at 25 C. The initial microstructure influenced the corrosion performance of studied joints due to the formation of secondary phases and their volume fraction changed the galvanic corrosion response of Mg materials. Nd-La addition enhanced the corrosion resistance of IF-Mg joints, where two times higher corrosion resistance was obtained by IF-AZ31B-0.5Nd-0.1La (1110 mils/year (mpy)) joint than IF-AZ31B (3670 mpy). The cross section locations had different secondary phase (SP) volume fraction, SP-distribution and grain orientations which altered the corrosion behavior of joined materials. After the clinching process, the deformed section of IF-AZ31B-0.5Nd-0.1La and IF-AZ31B showed lower corrosion rate than undeformed sections 1040 and 1110 mpy and 2820 and 3670 mpy, respectively.Öğe The Effect of Homogenization Parameters on the Corrosion Rate of Mg-Al-Sn-Mn-La-Gd Alloys(Springer, 2022) Kara, Ismail Hakki; ozsoy, EsraThe corrosion behavior of Mg-2.5Al- 1.0Sn- 0.3Mn- 0.4La-0.16Gd and Mg-2.5Al- 1.0Sn- 0.3Mn- 0.4La-1.33Gd alloys was studied by considering of different homogenization parameters such as 4-16 h durations and 300-350 degrees C temperatures. Potentiodynamic and immersion corrosion tests were carried out in the 3.5 %NaCl medium to homogenized specimens. It was discovered that the higher amount of Gd influenced the corrosion rate of investigated samples positively, where the higher density of secondary phases possessed an important role on corrosion resistance. 0.0051 mils per year value was obtained by the specimen of Mg-2.5Al- 1.0Sn- 0.3Mn- 0.4La-1.33Gd alloy (12 h-at 350 degrees C) due to the formed Mg-5(Gd, La) type secondary phases. To understand the relationship between corrosion resistance and microstructure properties, scanning electron microscopy and x-ray diffraction methods were employed. Furthermore, energy dispersive spectroscopy was applied to secondary phases of investigated specimens to obtain which corrosion mechanism is dominant and how effect the corrosion resistance. Corroded surfaces have demonstrated that the pitting corrosion morphology dominantly has occurred on the highly corroded specimens, however corrugated-like morphology has resulted in the excellent corrosion resistance.Öğe The effect of hot rolling process on macro-texture and high-temperature mechanical properties of AZ31B alloy modified by Ca and Ce(Sage Publications Ltd, 2023) Kara, Ismail Hakki; Demirtas, HuseyinThis study examines the high-temperature tensile properties of AZ31 and AZ31-1.0Ca-0.2Ce alloys in different rolling directions. Tensile test results at 250 degrees C showed that the ductility of AZ31-1.0Ca-0.2Ce alloy increased threefold in the 90 degrees perpendicular direction to rolling direction. Moreover, both strength and elongation values of AZ31-1.0Ca-0.2Ce alloy were higher than those of AZ31. Macro-texture measurements revealed that AZ31 and AZ31-1.0Ca-0.2Ce alloys showed strong and weakened basal texture in the rolling direction, respectively. The combined effect of secondary phases and texture weakening increased the high-temperature ductility (49%) of AZ31-1.0Ca-0.2Ce. In the rolling direction, yield (YS) and ultimate tensile strength of AZ31-1.0Ca-0.2Ce were obtained as 115 and 121 MPa, respectively. These values were higher than AZ31 alloy due to the stronger texture of the non-basal planes. The fracture surface of AZ31 samples proved that the rough and crack-dominated surface led to brittle fracture formation. However, fine-sized dimples resulted in a ductile fracture in AZ31-1.0Ca-0.2Ce samples.Öğe The Immersion Corrosion Resistance of Shot Peening and MAO Applied on AZ31-0.5% La Sheets(Eos Assoc, 2020) Elmansouri, Galal; Kara, Ismail Hakki; Ahlatci, Hayrettin; Turen, YunusIn 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.Öğe Mechanical Properties of Pattern Welded 1075-15N20 Steels(Carl Hanser Verlag, 2014) Ozkan, Furkan; Kirdan, Hakan; Kara, Ismail Hakki; Husem, Fazil; Ozcelik, Sait; Akinay, Yuksel; Cug, HarunForged welded (damascus) steels are produced by traditional methods and mostly used in the design of decorative tools. These steels are well-known for their good mechanical properties. The process for making forged welded (damascus) steel consists of stacking alternating sheets of different kinds of steel on top of each other and then forge welding them together. In this study, the steels 1075 and 15N20 were used for the forging and folding procedure. The effect of fold numbers on the microstructure and mechanical behavior were investigated. The steel consisted of both materials, 54 and 250 layers, respectively, produced by forge welding. The pattern layers are homogeneous and regular, but after the process sections with up to 54 pattern layers were irregular. Steel 1075 has a pearlitic microstructure, while steel 15N20 has a ferritic microstructure. The impact toughness and tensile strength of the folded steels improved with increasing the number of folds.Öğe Microstructural, Mechanical, and Tribological Properties of Mg-3Al-1Sn-1Nd-Mn Alloy(Springer, 2021) Kara, Ismail Hakki; Incesu, AlperIn this study, Mg-3Al-1Sn-1Nd-Mn alloy was produced by low-pressure die casting method and homogenization heat treated (HHT) at 400 degrees C for 16 hrs. Microstructural characterization of the alloy was done by XRF, XRD, LOM and SEM-EDS analyses. The microstructure of the alloy was composed of alpha-Mg, Al2Nd and Al11Nd3 phases. Hot rolling was applied to the HHT alloy at two different speeds 13.78 rpm [low speed rolling (LSR)] and 26.96 rpm [high-speed rolling (HSR)] at 350 degrees C. Microstructural changes were also carried out by LOM and SEM analyses. Mechanical properties (hardness and tensile properties) and wear performances of HHT, LSR and HSR samples were compared. SEM fractography was conducted on tension test samples to visualize the deformation and fracture behaviors. Also, worn surfaces of samples were investigated by SEM-EDS analysis. Abrasive, oxidation and delamination mechanisms were observed for worn surfaces of samples. To sum up, the mechanical properties of the HSR sample were higher compared to the HHT and LSR samples, and the wear rate was lower than HHT and LSR samples.Öğe Microstructure and corrosion properties of lanthanum-added AZ31 Mg alloys(Springer Heidelberg, 2018) Kara, Ismail Hakki; Ahlatci, Hayrettin; Turen, Yunus; Sun, YavuzIn this study, the effect of lanthanum (La) on microstructure and corrosion properties of hot-rolled AZ31 Mg alloys was investigated. Light optical microscopy, scanning electron microscopy, and X-ray diffraction were applied for microstructure analysis. Potentiodynamic corrosion and immersion tests were being tried to assess the La effect on corrosion behavior. Moreover, how the rolling parameters and surface smoothness were changed of the corrosion rate was evaluated. Corrosion performance was developed by adding La and the corrosion rate was changed with the rolling speed.Öğe Wear Behavior of Hot Rolled AZ31B and AZ31B-Nd-La Mg Alloys Tested at Different Angles to Rolling Direction(Springer, 2022) Kara, Ismail HakkiThe aim of this study is to investigate the direction-based dry wear behavior of hot rolled AZ31B and AZ31B-0.5wt.%Nd-0.1wt%La alloys which were deformed with two rolling speeds of 4.4 and 29.5 rpm. The twins and dynamic recrystallization mechanisms were introduced on microstructure of studied specimens dependent on the rolling speeds, where 4.4 rpm rolling imparted to higher hardness than 29.5 rpm due to twinning. Linear reciprocating ball-on flats wear tests were employed to measure the wear rate of 90 degrees, 45 degrees and 0 degrees ways to the rolling direction. To understand the relationship between wear behavior and microstructure properties, the light optical microscopy (LOM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) methods were employed. AZ31B-0.5wt.%Nd-0.1wt%La alloy was diverse from AZ31B because of dense fiber-like Al-11(Nd, La)(3) and Al-2(Nd, La) secondary phases. AZ31B demonstrated more wear rate than AZ31B-0.5wt.%Nd-0.1wt%La alloy at 90 degrees, 45 degrees and 0 degrees direction of wear tests. However, the wear rates order was obtained as 45 degrees>90 degrees>0 degrees for both alloys rolled at 29.5rpm rolling speed. Thus, the pole figure analysis was studied to obtain the effect of macro-texture on the wear behavior of alloys, where the orientation distribution of (0002) texture around the normal direction is wider than TD (90 degrees) than RD (0 degrees) for both investigated specimens. Furthermore, the worn surfaces were investigated by SEM and energy-dispersive spectroscopy (EDS) to obtain which wear mechanism is dominant and how affect the wear resistance. Commanding wear mechanisms were obtained as abrasion, oxidation and delamination.Öğe Wear Resistance of Sheet Magnesium Alloy AZ31 with Micro Arc Oxidation Coatings After Shot Peening(Springer, 2021) Elmensouri, Galal; Kara, Ismail Hakki; Ahlatci, Hayrettin; Turen, YunusThe wear resistance of sheet magnesium alloy AZ31 (Mg - 2.90% Al - 0.98% Zn - 0.13% Mn) with microarc oxidation coatings after shot peening is determined. The microstructure of the alloy is studied by scanning electron microscopy. The effect of the shot peening on formation of cracks and pores in the alloy after microarc oxidation and on the roughness of the surface is determined in order to predict the wear resistance of the alloy under dry friction.
