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Papers by yunus turen

Journal of Polymer Engineering

Production methods are changing day by day with the developing technology. Based on this idea, a ... more Production methods are changing day by day with the developing technology. Based on this idea, a new production logic and machine have been developed owing to polymer-supported powder injection molding (PIM). The ability of this newly designed machine (newPIM) to mold metal or ceramic powders supported by polymer binders is discussed in this study. By taking advantage of the polymer properties such as fluidity and sticking, powders are molded with a specially developed machine with high gas pressure in certain sizes. In this study, in which many parameters are processed from feedstock (FS) production to molding; metals Mg/316L and ceramics SiC/SiO2 powders have been used in different powder sizes and structures. In the newPIM process, polymers were included in four different recipes. Paraffin wax (PW), polyethylene glycol (PEG), polypropylene (PP), ethylene-vinyl acetate (EVA), poly-methyl methacrylate (PMMA) and low-density polyethylene (LDPE) have been employed in the FS with diff...

Journal of Materials Engineering and Performance

Biointerphases

In this study, casting, extrusion, biocorrosion, and corrosive wear properties of 0.5 wt. % (Zn, ... more In this study, casting, extrusion, biocorrosion, and corrosive wear properties of 0.5 wt. % (Zn, Ca, and Nd) element added Mg—3 wt. % Ag alloys were investigated. According to the test results, it was observed that the grain refinement occurred with the effect of Zn and Ca element additions in the as-cast alloys and thus some mechanical properties of the alloys improved. Similarly, the extrusion process provided grain refinement and improved mechanical properties. As a result of in vitro corrosion tests, similar results were also obtained in the as-cast alloys, while this situation became more apparent in the extruded alloys and exhibited more homogeneous corrosion properties. In the corrosive wear tests, the wear rate of the extruded alloys generally showed a decreasing trend. However, both the as-cast and extruded Mg—3 wt. %Ag—0.5 wt. % Ca alloys exhibited the lowest wear rate.

In this study, the effects of B₄C and SiC particle reinforcements on wear ... more In this study, the effects of B₄C and SiC particle reinforcements on wear properties of magnesium matrix metal composites produced by pressure infiltration method were investigated. AZ91 (9%Al-1%Zn) magnesium alloy was used as a matrix. AZ91 magnesium alloy was melted under an argon atmosphere. The melt was infiltrated to the particles with an appropriate pressure. Wear tests, hardness tests were performed respectively. Microstructure characterizations were examined by light optical (LOM) and scanning electron microscope (SEM). The results showed that uniform particle distributions were achieved in both B₄C and SiC reinforced composites. Wear behaviors of magnesium matrix metal composites changed as a function of type of particles. SiC reinforced composite has better wear performance and higher hardness than B₄C reinforced composite.

This study aimed for improving wear resistance of AM60 magnesium alloy by Ti addition (0, 0.2, 0.... more This study aimed for improving wear resistance of AM60 magnesium alloy by Ti addition (0, 0.2, 0.5, 1wt%Ti). An electric resistance furnace was used to produce alloys. Pure Mg together with Al, Al-Ti and Al-Mn were melted at 750 ⁰C in a stainless steel crucible under controlled Ar gas atmosphere and then poured into a metal mould preheated at 250 ⁰C. Microstructure characterizations were performed by light optical (LOM) and scanning electron microscope (SEM) after the wear test. Wear rates and friction coefficients were measured with a pin-on-disk type UTS-10 Tribometer test device under a load of 20N. The results showed that Ti addition altered the morphology and the amount of b-Mg₁₇Al₁₂ phase in the microstructure of AM60 alloy. b-Mg₁₇Al₁₂ phases on the grain boundaries were refined with increasing amount of Ti. An improvement in wear resistance...

Bilecik Şeyh Edebali Üniversitesi Fen Bilimleri Dergisi, 2021

Bu çalışmada ZM21 Magnezyum (Mg) alaşımına La ve Ca ilavesinin döküm ve hadde sonrası mikroyapı, ... more Bu çalışmada ZM21 Magnezyum (Mg) alaşımına La ve Ca ilavesinin döküm ve hadde sonrası mikroyapı, mekanik ve korozyon özellikleri incelenmiştir. Mikroyapı sonuçları incelendiğinde haddeleme sonrasında La ilaveli alaşımda taneler incelirken ikincil fazların bir miktar hadde yönünde uzadığı görülmüştür. Bundan farklı olarak Ca ilaveli alaşımda oluşan fazların haddeleme esnasında kırıldığı tespit edilmiştir. XRD sonuçlarına göre alaşımlarda MgZn, MgZn 2 , MgZn 3 , C5Zn 3 , Ca 2 Mg 6 Zn 3 , LaZn 2 , LaMg 3 fazlarının oluştuğu görüldü. Daldırma korozyon özelliğine bakıldığında ZM21 Mg alaşımına kıyasla ZM21+0,5(La) Mg alaşımının hem döküm hem hadde olarak daha az ağırlık kaybı yaşanmıştır. Fakat döküm halinde ZM21+0,5(Ca) alaşımı daha düşük, haddelenmiş olarakta çok daha fazla ağırlık kaybı sergilemiştir.

Engineering, Technology & Applied Science Research, 2020

In this study, the effect of Shot Peening (SP) and Micro Arc Oxidation (MAO) process on the corro... more 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.

Advanced Science, Engineering and Medicine, 2019

Engineering, Technology & Applied Science Research, 2020

In this study, AZ31 Mg alloys with added Ca and Ce were produced by low pressure die casting and ... more 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.

Engineering Science and Technology, an International Journal, 2018

In this work we aim to investigate fatigue strengths of the steel filaments in diameter of 0.25 m... more In this work we aim to investigate fatigue strengths of the steel filaments in diameter of 0.25 mm with three different Carbon (0.70%C, 0.80%C and 0.90%C) and with four different drawing strains (3.25, 3.37, 3.71 and 3.76) by the pure bending test method. All fatigue tests have been carried out at room temperature and at a frequency of 10 Hz via a custom manufactured pure bending testing machine of which the fully reserved strain value, R = emin/emax, is −1. The applied value of cyclic deformation, e, has been chosen from the range 0.20%–1.07% as bending strain. The plots of S-N (Strain–Cycle) curves are based on high cycle fatigue (HCF) life is greater than or equal to 104 cycles. The fatigue deformation limit values have been determined as 0.55% units and 0.20% units for the steels of the 0.25NT-70C and 0.25UT-90C quality, respectively. The increase in hardness resulting from the microstructural thinning (due to drawing strain) increases the fatigue deformation limit of the steels...

Nevşehir Bilim ve Teknoloji Dergisi, 2020

In this study, in the range of 0.2% to 0.5% Nd elements were added to AZ31 alloys produced by low... more In this study, in the range of 0.2% to 0.5% Nd elements were added to AZ31 alloys produced by low pressure die casting method. The hot rolling process was applied to these produced alloys at 400 °C with 4,7 and 10 meter per minute rolling speeds at 30% deformation rate per pass. Micro arc oxidation (MAO) were applied to produced alloys. The wear resistance of samples extracted from sheets that have included different surface morphology after various Nd adding were investigated at dry condition according to ASTM G-133 of the standard test method for linearly reciprocating ball-on-flat sliding wear. The effect of MAO coating and Nd addition on wear resistance of investigated alloys was studied systematically on the base of microstructure analysis.

International Journal of Materials Science and Applications, 2018

In this study, the effect of Pb element addition varied between 0.2-0.4 wt.% on the microstructur... more In this study, the effect of Pb element addition varied between 0.2-0.4 wt.% on the microstructure and casting properties of AZ91 magnesium alloy were investigated. The microstructural results showed that as increasing Pb additions into the AZ91 alloy, the grains and the Mg 17 Al 12 intermetallic phase becomes thinner. When examining the effect on casting properties; It was observed that the fluidity of AZ91 alloy increased as the increasing of Pb additions. In the hot tear tests two different mold systems were used. Hot tearing were observed in the longest section in the tests using "the mold same diameter, different lengths" and when the "the mold different diameter, same lengths" were used, hot tears were observed in all of the molds with diameters of 6, 8, 10 mm. Hot tearings were observed in 0.2 wt.% and 0.3 wt.% Pb additions, while hot tearing was not observed when this ratio increased to 0.4% for the 12 mm diameter test specimens. There was also not hot tearing were observed in any sample when the sample diameter was 16 mm.

Materials Research Express, 2019

In this study, the microstructure, mechanical properties and corrosion resistance of as-cast and ... more In this study, the microstructure, mechanical properties and corrosion resistance of as-cast and as-extruded WE43-xZn (x = 0, 0.5, 1.0 wt%) magnesium alloys were investigated. The microstructure of the as-cast alloys showed that the WE43-xZn alloys contained Mg41Nd5 and Mg24Y5 intermetallic compounds. Besides, LPSO (Long-period stacking ordered) type Zn-rich phases were also originated in the microstructure with increasing Zn content. Furthermore, LPSO structure was observed both in the α-Mg grain and at the grain boundaries in Zn-containing WE43 alloys. The Vickers hardness values increased by the raising Zn content in the as-cast, solution treated and as-extruded WE43-xZn alloys. It was observed that yield strength (YS) increased gradually by the addition of Zn content, but 0.5 wt% Zn addition to as-cast WE43 alloy resulted in much more improvements on the ultimate tensile strength (UTS) and elongation % (EL) values compared to as-cast WE43-1.0Zn alloy. It was seen that mechanical properties improved with increasing Zn content for the as-extruded alloys. The as-cast specimens showed that corrosion resistance improved by increasing Zn content due to the presence of LPSO structures, but in the extruded alloys it varied in relation to the presence and distribution of second phases and also the morfologies of LPSO structures.

Journal of Materials Engineering and Performance, 2019

Microstructure, tensile and wear properties of as-cast A4 (Mg-4Al), AE41 (Mg-4Al-0.5Ce-0.5La), AS... more Microstructure, tensile and wear properties of as-cast A4 (Mg-4Al), AE41 (Mg-4Al-0.5Ce-0.5La), AS41 (Mg-4Al-1Si) and AJ41 (Mg-4Al-1Sr) alloys were investigated, and the results were compared with each other in this study. Microstructures were investigated by XRD, optical and scanning electron microscopes. Tensile tests were conducted at both room and elevated temperatures. Tribological properties were examined by pin-on-disk wear tests under different applied loads. Microstructure characterizations revealed that the volume fraction of second phases considerably increased by alloying additions of 1 wt.% Ce/ La, Si and Sr. The microstructure of A4 alloy consisted of a-Mg grains and divorced b-Mg 17 Al 12 phases. After individual alloying additions of 1 wt.% Ce/La, Si and Sr, the secondary phases were primarily replaced by needle-shaped and massive blocky-shaped Al 11 (Ce,La) 3 phases in AE41 alloy, Chinese-scripttype Mg 2 Si phases in AS41 alloy and divorced globular-like and massive blocky-shaped Al 4 Sr and (Mg,Al) 17 Sr 2 phases in AJ41 alloy. The tensile tests showed that at both room and elevated temperatures alloying additions of 1 wt.% Ce/La, Si and Sr resulted in an increase in the strength but a decrease in the ductility. Among the studied alloys, AS41 alloy exhibited the best strength. Wear test results showed that AE41 and AJ41 alloys similarly exhibited the best wear resistance owing to the presence of hard and dense intermetallics. Abrasion was the main wear mechanism under low applied loads while delamination, adhesion and oxidation mechanisms were majorly observed under high applied loads.

Materials Research Express, 2019

Universal Journal of Materials Science, 2019

Heat treatment is the most commonly used production step which can change the overall mechanical ... more Heat treatment is the most commonly used production step which can change the overall mechanical properties of the material without changing the chemical composition. Among the heat treatment methods, accelerated cooling has been regarded as one of the most important method for obtaining good mechanical properties. Today, this method is used in the manufacture of thin pearlitic steel, double phase steel, bainitic steel in the production process of many different quality and size products from construction bar to profile. In the scope of this study, investigations were carried out on S355J2 equal angles section profiles produced by hot rolling method. It was observed that intensive inclusions were found in all of the materials and the mechanical strength could not be met at low rolling ratios. Particularly, these materials with low impact resistance have been subjected to accelerated cooling process in order to increase their impact strength. As a result of the accelerated cooling process, significant increases in impact strength have been observed, particularly with the change of microstructure.

Uluslararası Muhendislik Arastirma ve Gelistirme Dergisi, 2019

Öz Mevcut kullanım alanları gün geçtikçe artış gösteren Mg alaşımlarının, teknolojik gelişmelere ... more Öz Mevcut kullanım alanları gün geçtikçe artış gösteren Mg alaşımlarının, teknolojik gelişmelere uyum sağlayabilmesi için mekanik özellikler bakımından daha fazla geliştirilmesi gerekliliği ortaya çıkmıştır. Günümüzde çözünebilir biyo-malzeme olarak sağlık alanında da kullanılmaya başlayan Mg ve alaşımlarına kazandırılan fiziksel ve mekanik özellikler malzemenin kullanım ömrünü tayin etmektedir. Dolayısıyla bu çalışmada, AZ91 serisi Mg alaşımına farklı oranlarda (%0.2-%0.5 ve %1.0) Sb elementi ilavesi ve katılaşma hızının da etkisiyle mekanik özelliklerinin geliştirilmesi amaçlanmıştır. Yapılan çalışmanın neticesinde sonuçlar incelendiğinde; AZ91 alaşımının genel olarak tane yapısının α-Mg ve tane sınırları boyunca yayılan β-Mg17Al12 fazından oluştuğu saptanmıştır. Hızlı soğumanın tane yapısında küçülmelere sebep olduğu bununla birlikte tane sınırlarında bulunan Mg17Al12 intermetalik fazının incelip parçalandığı tespit edilmiştir. Tespit edilen bu etkilerin neticesinde de alaşımın çekme, akma ve uzama değerlerinde artışın olduğu gözlenmiştir. Bununla birlikte AZ91 alaşımına ilave edilen Sb ile yapıda Mg3Sb2 fazı oluşmuştur. Bu intermetalik fazın yapıda meydana getirdiği değişiklikler ile alaşımın mekanik özelliklerinde artış izlenmiştir. AZ91 alaşımının çekme dayanımı Sb ilavesi ile 163 MPa seviyelerinden 217 MPa seviyelerine kadar iyileşmiştir. Sb ilavesiyle AZ91 alaşımında sertlik değerleri yaklaşık 57 HV değerlerinden 81 HV değerlerine yükselmiştir.

Rare Metals, 2018

Microstructure, mechanical properties and corrosion resistance of as-cast and as-extruded Mg–4 wt... more Microstructure, mechanical properties and corrosion resistance of as-cast and as-extruded Mg–4 wt% Zn–1 wt% La magnesium alloys were investigated. The alloys were produced by low-pressure die casting method and extruded at 350 °C after homogenization at 400 °C for 24 h. The results show that the as-cast alloy mainly consists of primary α-Mg matrix and Mg–Zn–La ternary second phases (also called T-Phase) along grain boundaries and isolated spherical particles inside the grains. After extrusion at 350 °C, the average grain size decreases by 81% due to dynamic recrystallization mechanism and T-phase particles are distributed along the extrusion direction. The elongation, yield strength and tensile strength of the as-cast Mg–4Zn–1La alloy increase by 179%, 90% and 40%, respectively, as a result of the extrusion process. The as-extruded Mg–4Zn–1La alloy shows better corrosion resistance than the as-cast alloy due to increased grain boundaries and decreased content of T-phase.

Materials Research Express, 2018

Materials Chemistry and Physics, 2018

The microstructure, texture and mechanical properties of Mg-6wt%Zn-0.5wt%Zr (ZK60) alloys with di... more The microstructure, texture and mechanical properties of Mg-6wt%Zn-0.5wt%Zr (ZK60) alloys with different La contents (0, 0.5 and 1 wt%) were investigated. The alloys were produced by lowpressure die casting and extruded at 300 °C and 400 °C, following homogenization at 400 °C for 24 h. La addition to ZK60 alloy resulted in a formation of Mg-Zn-La ternary phase, generating a semicontinuous network structure in their as-cast state. After extrusion, secondary phases were broken into fine particles distributed along the extrusion direction. These fragmented particles led to a nucleation of new grains around them i.e. particle stimulated nucleation (PSN), and promoted dynamic recrystallization (DRX) during extrusion. Therefore, increasing La content led to an increase in DRX fraction. Higher extrusion temperature resulted in larger DRXed grains and higher DRX fraction. The basal texture intensity was also decreased with increasing La addition and extrusion temperature by PSN mechanism and solute atoms of La. The ZK60-1La alloy extruded at 300 °C showed a superior yield strength of 311 MPa and ultimate tensile strength of 360 MPa as a result of significant grain refinement and dispersion strengthening. Increasing extrusion temperature resulted in a decrease in yield and ultimate tensile strengths and increase in ductility.

Journal of Polymer Engineering

Production methods are changing day by day with the developing technology. Based on this idea, a ... more Production methods are changing day by day with the developing technology. Based on this idea, a new production logic and machine have been developed owing to polymer-supported powder injection molding (PIM). The ability of this newly designed machine (newPIM) to mold metal or ceramic powders supported by polymer binders is discussed in this study. By taking advantage of the polymer properties such as fluidity and sticking, powders are molded with a specially developed machine with high gas pressure in certain sizes. In this study, in which many parameters are processed from feedstock (FS) production to molding; metals Mg/316L and ceramics SiC/SiO2 powders have been used in different powder sizes and structures. In the newPIM process, polymers were included in four different recipes. Paraffin wax (PW), polyethylene glycol (PEG), polypropylene (PP), ethylene-vinyl acetate (EVA), poly-methyl methacrylate (PMMA) and low-density polyethylene (LDPE) have been employed in the FS with diff...

Journal of Materials Engineering and Performance

Biointerphases

In this study, casting, extrusion, biocorrosion, and corrosive wear properties of 0.5 wt. % (Zn, ... more In this study, casting, extrusion, biocorrosion, and corrosive wear properties of 0.5 wt. % (Zn, Ca, and Nd) element added Mg—3 wt. % Ag alloys were investigated. According to the test results, it was observed that the grain refinement occurred with the effect of Zn and Ca element additions in the as-cast alloys and thus some mechanical properties of the alloys improved. Similarly, the extrusion process provided grain refinement and improved mechanical properties. As a result of in vitro corrosion tests, similar results were also obtained in the as-cast alloys, while this situation became more apparent in the extruded alloys and exhibited more homogeneous corrosion properties. In the corrosive wear tests, the wear rate of the extruded alloys generally showed a decreasing trend. However, both the as-cast and extruded Mg—3 wt. %Ag—0.5 wt. % Ca alloys exhibited the lowest wear rate.

In this study, the effects of B₄C and SiC particle reinforcements on wear ... more In this study, the effects of B₄C and SiC particle reinforcements on wear properties of magnesium matrix metal composites produced by pressure infiltration method were investigated. AZ91 (9%Al-1%Zn) magnesium alloy was used as a matrix. AZ91 magnesium alloy was melted under an argon atmosphere. The melt was infiltrated to the particles with an appropriate pressure. Wear tests, hardness tests were performed respectively. Microstructure characterizations were examined by light optical (LOM) and scanning electron microscope (SEM). The results showed that uniform particle distributions were achieved in both B₄C and SiC reinforced composites. Wear behaviors of magnesium matrix metal composites changed as a function of type of particles. SiC reinforced composite has better wear performance and higher hardness than B₄C reinforced composite.

This study aimed for improving wear resistance of AM60 magnesium alloy by Ti addition (0, 0.2, 0.... more This study aimed for improving wear resistance of AM60 magnesium alloy by Ti addition (0, 0.2, 0.5, 1wt%Ti). An electric resistance furnace was used to produce alloys. Pure Mg together with Al, Al-Ti and Al-Mn were melted at 750 ⁰C in a stainless steel crucible under controlled Ar gas atmosphere and then poured into a metal mould preheated at 250 ⁰C. Microstructure characterizations were performed by light optical (LOM) and scanning electron microscope (SEM) after the wear test. Wear rates and friction coefficients were measured with a pin-on-disk type UTS-10 Tribometer test device under a load of 20N. The results showed that Ti addition altered the morphology and the amount of b-Mg₁₇Al₁₂ phase in the microstructure of AM60 alloy. b-Mg₁₇Al₁₂ phases on the grain boundaries were refined with increasing amount of Ti. An improvement in wear resistance...

Bilecik Şeyh Edebali Üniversitesi Fen Bilimleri Dergisi, 2021

Bu çalışmada ZM21 Magnezyum (Mg) alaşımına La ve Ca ilavesinin döküm ve hadde sonrası mikroyapı, ... more Bu çalışmada ZM21 Magnezyum (Mg) alaşımına La ve Ca ilavesinin döküm ve hadde sonrası mikroyapı, mekanik ve korozyon özellikleri incelenmiştir. Mikroyapı sonuçları incelendiğinde haddeleme sonrasında La ilaveli alaşımda taneler incelirken ikincil fazların bir miktar hadde yönünde uzadığı görülmüştür. Bundan farklı olarak Ca ilaveli alaşımda oluşan fazların haddeleme esnasında kırıldığı tespit edilmiştir. XRD sonuçlarına göre alaşımlarda MgZn, MgZn 2 , MgZn 3 , C5Zn 3 , Ca 2 Mg 6 Zn 3 , LaZn 2 , LaMg 3 fazlarının oluştuğu görüldü. Daldırma korozyon özelliğine bakıldığında ZM21 Mg alaşımına kıyasla ZM21+0,5(La) Mg alaşımının hem döküm hem hadde olarak daha az ağırlık kaybı yaşanmıştır. Fakat döküm halinde ZM21+0,5(Ca) alaşımı daha düşük, haddelenmiş olarakta çok daha fazla ağırlık kaybı sergilemiştir.

Engineering, Technology & Applied Science Research, 2020

In this study, the effect of Shot Peening (SP) and Micro Arc Oxidation (MAO) process on the corro... more 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.

Advanced Science, Engineering and Medicine, 2019

Engineering, Technology & Applied Science Research, 2020

In this study, AZ31 Mg alloys with added Ca and Ce were produced by low pressure die casting and ... more 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.

Engineering Science and Technology, an International Journal, 2018

In this work we aim to investigate fatigue strengths of the steel filaments in diameter of 0.25 m... more In this work we aim to investigate fatigue strengths of the steel filaments in diameter of 0.25 mm with three different Carbon (0.70%C, 0.80%C and 0.90%C) and with four different drawing strains (3.25, 3.37, 3.71 and 3.76) by the pure bending test method. All fatigue tests have been carried out at room temperature and at a frequency of 10 Hz via a custom manufactured pure bending testing machine of which the fully reserved strain value, R = emin/emax, is −1. The applied value of cyclic deformation, e, has been chosen from the range 0.20%–1.07% as bending strain. The plots of S-N (Strain–Cycle) curves are based on high cycle fatigue (HCF) life is greater than or equal to 104 cycles. The fatigue deformation limit values have been determined as 0.55% units and 0.20% units for the steels of the 0.25NT-70C and 0.25UT-90C quality, respectively. The increase in hardness resulting from the microstructural thinning (due to drawing strain) increases the fatigue deformation limit of the steels...

Nevşehir Bilim ve Teknoloji Dergisi, 2020

In this study, in the range of 0.2% to 0.5% Nd elements were added to AZ31 alloys produced by low... more In this study, in the range of 0.2% to 0.5% Nd elements were added to AZ31 alloys produced by low pressure die casting method. The hot rolling process was applied to these produced alloys at 400 °C with 4,7 and 10 meter per minute rolling speeds at 30% deformation rate per pass. Micro arc oxidation (MAO) were applied to produced alloys. The wear resistance of samples extracted from sheets that have included different surface morphology after various Nd adding were investigated at dry condition according to ASTM G-133 of the standard test method for linearly reciprocating ball-on-flat sliding wear. The effect of MAO coating and Nd addition on wear resistance of investigated alloys was studied systematically on the base of microstructure analysis.

International Journal of Materials Science and Applications, 2018

In this study, the effect of Pb element addition varied between 0.2-0.4 wt.% on the microstructur... more In this study, the effect of Pb element addition varied between 0.2-0.4 wt.% on the microstructure and casting properties of AZ91 magnesium alloy were investigated. The microstructural results showed that as increasing Pb additions into the AZ91 alloy, the grains and the Mg 17 Al 12 intermetallic phase becomes thinner. When examining the effect on casting properties; It was observed that the fluidity of AZ91 alloy increased as the increasing of Pb additions. In the hot tear tests two different mold systems were used. Hot tearing were observed in the longest section in the tests using "the mold same diameter, different lengths" and when the "the mold different diameter, same lengths" were used, hot tears were observed in all of the molds with diameters of 6, 8, 10 mm. Hot tearings were observed in 0.2 wt.% and 0.3 wt.% Pb additions, while hot tearing was not observed when this ratio increased to 0.4% for the 12 mm diameter test specimens. There was also not hot tearing were observed in any sample when the sample diameter was 16 mm.

Materials Research Express, 2019

In this study, the microstructure, mechanical properties and corrosion resistance of as-cast and ... more In this study, the microstructure, mechanical properties and corrosion resistance of as-cast and as-extruded WE43-xZn (x = 0, 0.5, 1.0 wt%) magnesium alloys were investigated. The microstructure of the as-cast alloys showed that the WE43-xZn alloys contained Mg41Nd5 and Mg24Y5 intermetallic compounds. Besides, LPSO (Long-period stacking ordered) type Zn-rich phases were also originated in the microstructure with increasing Zn content. Furthermore, LPSO structure was observed both in the α-Mg grain and at the grain boundaries in Zn-containing WE43 alloys. The Vickers hardness values increased by the raising Zn content in the as-cast, solution treated and as-extruded WE43-xZn alloys. It was observed that yield strength (YS) increased gradually by the addition of Zn content, but 0.5 wt% Zn addition to as-cast WE43 alloy resulted in much more improvements on the ultimate tensile strength (UTS) and elongation % (EL) values compared to as-cast WE43-1.0Zn alloy. It was seen that mechanical properties improved with increasing Zn content for the as-extruded alloys. The as-cast specimens showed that corrosion resistance improved by increasing Zn content due to the presence of LPSO structures, but in the extruded alloys it varied in relation to the presence and distribution of second phases and also the morfologies of LPSO structures.

Journal of Materials Engineering and Performance, 2019

Microstructure, tensile and wear properties of as-cast A4 (Mg-4Al), AE41 (Mg-4Al-0.5Ce-0.5La), AS... more Microstructure, tensile and wear properties of as-cast A4 (Mg-4Al), AE41 (Mg-4Al-0.5Ce-0.5La), AS41 (Mg-4Al-1Si) and AJ41 (Mg-4Al-1Sr) alloys were investigated, and the results were compared with each other in this study. Microstructures were investigated by XRD, optical and scanning electron microscopes. Tensile tests were conducted at both room and elevated temperatures. Tribological properties were examined by pin-on-disk wear tests under different applied loads. Microstructure characterizations revealed that the volume fraction of second phases considerably increased by alloying additions of 1 wt.% Ce/ La, Si and Sr. The microstructure of A4 alloy consisted of a-Mg grains and divorced b-Mg 17 Al 12 phases. After individual alloying additions of 1 wt.% Ce/La, Si and Sr, the secondary phases were primarily replaced by needle-shaped and massive blocky-shaped Al 11 (Ce,La) 3 phases in AE41 alloy, Chinese-scripttype Mg 2 Si phases in AS41 alloy and divorced globular-like and massive blocky-shaped Al 4 Sr and (Mg,Al) 17 Sr 2 phases in AJ41 alloy. The tensile tests showed that at both room and elevated temperatures alloying additions of 1 wt.% Ce/La, Si and Sr resulted in an increase in the strength but a decrease in the ductility. Among the studied alloys, AS41 alloy exhibited the best strength. Wear test results showed that AE41 and AJ41 alloys similarly exhibited the best wear resistance owing to the presence of hard and dense intermetallics. Abrasion was the main wear mechanism under low applied loads while delamination, adhesion and oxidation mechanisms were majorly observed under high applied loads.

Materials Research Express, 2019

Universal Journal of Materials Science, 2019

Heat treatment is the most commonly used production step which can change the overall mechanical ... more Heat treatment is the most commonly used production step which can change the overall mechanical properties of the material without changing the chemical composition. Among the heat treatment methods, accelerated cooling has been regarded as one of the most important method for obtaining good mechanical properties. Today, this method is used in the manufacture of thin pearlitic steel, double phase steel, bainitic steel in the production process of many different quality and size products from construction bar to profile. In the scope of this study, investigations were carried out on S355J2 equal angles section profiles produced by hot rolling method. It was observed that intensive inclusions were found in all of the materials and the mechanical strength could not be met at low rolling ratios. Particularly, these materials with low impact resistance have been subjected to accelerated cooling process in order to increase their impact strength. As a result of the accelerated cooling process, significant increases in impact strength have been observed, particularly with the change of microstructure.

Uluslararası Muhendislik Arastirma ve Gelistirme Dergisi, 2019

Öz Mevcut kullanım alanları gün geçtikçe artış gösteren Mg alaşımlarının, teknolojik gelişmelere ... more Öz Mevcut kullanım alanları gün geçtikçe artış gösteren Mg alaşımlarının, teknolojik gelişmelere uyum sağlayabilmesi için mekanik özellikler bakımından daha fazla geliştirilmesi gerekliliği ortaya çıkmıştır. Günümüzde çözünebilir biyo-malzeme olarak sağlık alanında da kullanılmaya başlayan Mg ve alaşımlarına kazandırılan fiziksel ve mekanik özellikler malzemenin kullanım ömrünü tayin etmektedir. Dolayısıyla bu çalışmada, AZ91 serisi Mg alaşımına farklı oranlarda (%0.2-%0.5 ve %1.0) Sb elementi ilavesi ve katılaşma hızının da etkisiyle mekanik özelliklerinin geliştirilmesi amaçlanmıştır. Yapılan çalışmanın neticesinde sonuçlar incelendiğinde; AZ91 alaşımının genel olarak tane yapısının α-Mg ve tane sınırları boyunca yayılan β-Mg17Al12 fazından oluştuğu saptanmıştır. Hızlı soğumanın tane yapısında küçülmelere sebep olduğu bununla birlikte tane sınırlarında bulunan Mg17Al12 intermetalik fazının incelip parçalandığı tespit edilmiştir. Tespit edilen bu etkilerin neticesinde de alaşımın çekme, akma ve uzama değerlerinde artışın olduğu gözlenmiştir. Bununla birlikte AZ91 alaşımına ilave edilen Sb ile yapıda Mg3Sb2 fazı oluşmuştur. Bu intermetalik fazın yapıda meydana getirdiği değişiklikler ile alaşımın mekanik özelliklerinde artış izlenmiştir. AZ91 alaşımının çekme dayanımı Sb ilavesi ile 163 MPa seviyelerinden 217 MPa seviyelerine kadar iyileşmiştir. Sb ilavesiyle AZ91 alaşımında sertlik değerleri yaklaşık 57 HV değerlerinden 81 HV değerlerine yükselmiştir.

Rare Metals, 2018

Microstructure, mechanical properties and corrosion resistance of as-cast and as-extruded Mg–4 wt... more Microstructure, mechanical properties and corrosion resistance of as-cast and as-extruded Mg–4 wt% Zn–1 wt% La magnesium alloys were investigated. The alloys were produced by low-pressure die casting method and extruded at 350 °C after homogenization at 400 °C for 24 h. The results show that the as-cast alloy mainly consists of primary α-Mg matrix and Mg–Zn–La ternary second phases (also called T-Phase) along grain boundaries and isolated spherical particles inside the grains. After extrusion at 350 °C, the average grain size decreases by 81% due to dynamic recrystallization mechanism and T-phase particles are distributed along the extrusion direction. The elongation, yield strength and tensile strength of the as-cast Mg–4Zn–1La alloy increase by 179%, 90% and 40%, respectively, as a result of the extrusion process. The as-extruded Mg–4Zn–1La alloy shows better corrosion resistance than the as-cast alloy due to increased grain boundaries and decreased content of T-phase.

Materials Research Express, 2018

Materials Chemistry and Physics, 2018

The microstructure, texture and mechanical properties of Mg-6wt%Zn-0.5wt%Zr (ZK60) alloys with di... more The microstructure, texture and mechanical properties of Mg-6wt%Zn-0.5wt%Zr (ZK60) alloys with different La contents (0, 0.5 and 1 wt%) were investigated. The alloys were produced by lowpressure die casting and extruded at 300 °C and 400 °C, following homogenization at 400 °C for 24 h. La addition to ZK60 alloy resulted in a formation of Mg-Zn-La ternary phase, generating a semicontinuous network structure in their as-cast state. After extrusion, secondary phases were broken into fine particles distributed along the extrusion direction. These fragmented particles led to a nucleation of new grains around them i.e. particle stimulated nucleation (PSN), and promoted dynamic recrystallization (DRX) during extrusion. Therefore, increasing La content led to an increase in DRX fraction. Higher extrusion temperature resulted in larger DRXed grains and higher DRX fraction. The basal texture intensity was also decreased with increasing La addition and extrusion temperature by PSN mechanism and solute atoms of La. The ZK60-1La alloy extruded at 300 °C showed a superior yield strength of 311 MPa and ultimate tensile strength of 360 MPa as a result of significant grain refinement and dispersion strengthening. Increasing extrusion temperature resulted in a decrease in yield and ultimate tensile strengths and increase in ductility.