In this study, the different heat-treated-state 2024 Al-alloys were friction stir welded. The ten... more In this study, the different heat-treated-state 2024 Al-alloys were friction stir welded. The tensile properties of the joints have a tendency to increase with the precipitation hardening of the base material. The peak tensile properties have been obtained in the T6 (100°C – 10h) joint. It is observed that the weld zone is strengthened by the friction stir welding process
Grain boundary particles of a ternary, a Mn-containing and a Zr-containing Al-Zn-Mg alloys have b... more Grain boundary particles of a ternary, a Mn-containing and a Zr-containing Al-Zn-Mg alloys have been investigated. In the Mn-containing alloy, dispersoids are encountered within the grains as well as at the grain boundaries (GBs) together with the equilibrium η-phase. Large Mn-bearing particles are also present at the grain boundaries in this alloy, however they do not pin the GBs as the Zr-bearing particles. The distribution of the Zr-bearing dispersoids is observed to be irregular both in the grain itself and at the grain boundaries. These particles effectively impede grain growth.
Dry sliding wear of Al-Si cast alloys with three different compositions and different microstruct... more Dry sliding wear of Al-Si cast alloys with three different compositions and different microstructures have been examined. A pin-on-disk machine was used for this purpose with silicon carbide paper counterface. Worn surfaces and microstructures of Al-Si alloys were examined by scanning electron microscopy and optical microscopy, respectively. Optical microscopy examinations revealed that the microstructures of these alloys were altered by heal treatments and with Na additions. The results show that the microhardness and the wear resistance increase as the silicon content increases. Spheroidising heat-treatment and No-modification are observed to enhance the hardness and the wear resistance of these alloys.
The effect of notch angle and depth on the tensile properties of a peak-aged commercial 7075 allo... more The effect of notch angle and depth on the tensile properties of a peak-aged commercial 7075 alloy has been investigated. Although there seems to be little or no effect of the specimen geometry on toughness, there is a notch effect on tensile properties and this is more prono unced when the notch depth is higher. The crack extension has been observed to be predominantly transgranular by dimple formation in this alloy. A relationship between the dimple size measured on the fracture surfaces and the toughness has also been established. It is argued that the fracture toughness at the onset of fracture can be readily measured by using circumferentially notched bar tensile specimens.
A series of Al-Si-Mg-Cu alloys of different Si contents (namely 5%, 8% and 11%) and with and with... more A series of Al-Si-Mg-Cu alloys of different Si contents (namely 5%, 8% and 11%) and with and without Na-modification were cast and heat-trealed for 8 and 24 hours. Microstructures of these alloys were revealed and ofter the determination of the tensile properties, the fracture surfaces were examined. It hase been observed that the crack follows the Si phase in these alloys and therefore, the fracture toughness is not affected by the Si content. However, altering the morphology of the Si phase (i.e. spheroidising) affects the fracture toughness greatly; as the Si phase gets circular the fracture toughness increases, where the highest toughness is attained in the Na-modified alloys for all compositions.
In this investigation, a ball joint, which is the major functional part in a car has been modeled... more In this investigation, a ball joint, which is the major functional part in a car has been modeled to predict its fatigue life. In order to confirm the accuracy of the research, initially a modal analysis was performed, so the natural frequency of the structure was verified. Itb has been found that, the calculated natural frequency of the structure is much lower than its own natural frequency. The results, which were confirmed by experimental studies, have been interpreted by using analysis techniques and compared with theoretical outcomes.
Abstract The wear resistance of a series of Al-Si cast alloys with 5%, 8% and 11% silicon content... more Abstract The wear resistance of a series of Al-Si cast alloys with 5%, 8% and 11% silicon contents have been investigated after spheroidising heat treatments, and after coating these alloys by a plasma electrolytic oxidation (PEO) process for comparison. The alloys were subjected to wear tests by using SiC and steel counterfaces. The most remarkable observation is the increase in the wear resistance of the 5% Si containing alloy against SiC counterface, which is 70 times. However, the increase in the wear resistance is 5 times in the 11% Si containing alloy under same conditions, and only about 50% increase is observed when the counterface is steel. It is argued that, coating of these alloys by plasma electrolytic oxidation improves the wear resistance more effectively if the silicon content of the alloy is low, since the silicates (or aluminosilicates) in the coating layer has deleterious effect on wear resistance.
This collection of 26 papers treats both the basics as well as new developments in governing reso... more This collection of 26 papers treats both the basics as well as new developments in governing resolution, contrast, and 3D image formation and processing. It offers current information about fluorescent molecules, imaging software, and new commercial trends. The applications are in both the medical r
In this study, the different heat-treated-state 2024 Al-alloys were friction stir welded. The ten... more In this study, the different heat-treated-state 2024 Al-alloys were friction stir welded. The tensile properties of the joints have a tendency to increase with the precipitation hardening of the base material. The peak tensile properties have been obtained in the T6 (100°C – 10h) joint. It is observed that the weld zone is strengthened by the friction stir welding process
Grain boundary particles of a ternary, a Mn-containing and a Zr-containing Al-Zn-Mg alloys have b... more Grain boundary particles of a ternary, a Mn-containing and a Zr-containing Al-Zn-Mg alloys have been investigated. In the Mn-containing alloy, dispersoids are encountered within the grains as well as at the grain boundaries (GBs) together with the equilibrium η-phase. Large Mn-bearing particles are also present at the grain boundaries in this alloy, however they do not pin the GBs as the Zr-bearing particles. The distribution of the Zr-bearing dispersoids is observed to be irregular both in the grain itself and at the grain boundaries. These particles effectively impede grain growth.
Dry sliding wear of Al-Si cast alloys with three different compositions and different microstruct... more Dry sliding wear of Al-Si cast alloys with three different compositions and different microstructures have been examined. A pin-on-disk machine was used for this purpose with silicon carbide paper counterface. Worn surfaces and microstructures of Al-Si alloys were examined by scanning electron microscopy and optical microscopy, respectively. Optical microscopy examinations revealed that the microstructures of these alloys were altered by heal treatments and with Na additions. The results show that the microhardness and the wear resistance increase as the silicon content increases. Spheroidising heat-treatment and No-modification are observed to enhance the hardness and the wear resistance of these alloys.
The effect of notch angle and depth on the tensile properties of a peak-aged commercial 7075 allo... more The effect of notch angle and depth on the tensile properties of a peak-aged commercial 7075 alloy has been investigated. Although there seems to be little or no effect of the specimen geometry on toughness, there is a notch effect on tensile properties and this is more prono unced when the notch depth is higher. The crack extension has been observed to be predominantly transgranular by dimple formation in this alloy. A relationship between the dimple size measured on the fracture surfaces and the toughness has also been established. It is argued that the fracture toughness at the onset of fracture can be readily measured by using circumferentially notched bar tensile specimens.
A series of Al-Si-Mg-Cu alloys of different Si contents (namely 5%, 8% and 11%) and with and with... more A series of Al-Si-Mg-Cu alloys of different Si contents (namely 5%, 8% and 11%) and with and without Na-modification were cast and heat-trealed for 8 and 24 hours. Microstructures of these alloys were revealed and ofter the determination of the tensile properties, the fracture surfaces were examined. It hase been observed that the crack follows the Si phase in these alloys and therefore, the fracture toughness is not affected by the Si content. However, altering the morphology of the Si phase (i.e. spheroidising) affects the fracture toughness greatly; as the Si phase gets circular the fracture toughness increases, where the highest toughness is attained in the Na-modified alloys for all compositions.
In this investigation, a ball joint, which is the major functional part in a car has been modeled... more In this investigation, a ball joint, which is the major functional part in a car has been modeled to predict its fatigue life. In order to confirm the accuracy of the research, initially a modal analysis was performed, so the natural frequency of the structure was verified. Itb has been found that, the calculated natural frequency of the structure is much lower than its own natural frequency. The results, which were confirmed by experimental studies, have been interpreted by using analysis techniques and compared with theoretical outcomes.
Abstract The wear resistance of a series of Al-Si cast alloys with 5%, 8% and 11% silicon content... more Abstract The wear resistance of a series of Al-Si cast alloys with 5%, 8% and 11% silicon contents have been investigated after spheroidising heat treatments, and after coating these alloys by a plasma electrolytic oxidation (PEO) process for comparison. The alloys were subjected to wear tests by using SiC and steel counterfaces. The most remarkable observation is the increase in the wear resistance of the 5% Si containing alloy against SiC counterface, which is 70 times. However, the increase in the wear resistance is 5 times in the 11% Si containing alloy under same conditions, and only about 50% increase is observed when the counterface is steel. It is argued that, coating of these alloys by plasma electrolytic oxidation improves the wear resistance more effectively if the silicon content of the alloy is low, since the silicates (or aluminosilicates) in the coating layer has deleterious effect on wear resistance.
This collection of 26 papers treats both the basics as well as new developments in governing reso... more This collection of 26 papers treats both the basics as well as new developments in governing resolution, contrast, and 3D image formation and processing. It offers current information about fluorescent molecules, imaging software, and new commercial trends. The applications are in both the medical r
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Papers by Agah Uguz