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A comparative study of thermal sprayed Al₂ O₃-TiO₂ coatings on PM AISI 316L
(Elsevier, 2024-11-25) Tankal, Kenan; Güney, Bekir; Erden, Mehmet Akif
The widespread use of stainless steels (SS) in various applications is hindered by their inadequate wear resistance, hardness and high density. Structural metallic components fabricated via powder metallurgy (PM) exhibit lower densities compared to those produced by conventional methods due to their inherent high porosity. However, this compromises their mechanical and corrosion performance. This study has investigated the application of pure Al2O3 and Al2O3 + 13 %TiO2 powders with varying particle sizes on PM AISI 316L substrates to enhance their mechanical and wear properties. The phase composition, microhardness, coating morphology, surface roughness, porosity and wear rate of coated and uncoated samples were comparatively analysed to elucidate the influence of both TiO2 addition and coating powder particle size on the mechanical properties and surface morphology of the samples. Microstructural and XRD studies confirmed good mechanical and metallurgical bonding of the coatings to the substrate. All of the coated samples exhibited 24 to 34 times higher surface roughness and 1.3 to 2.1 times lower porosity values compared to the substrate. The finer sized TiO2 added alumina-based coating powder reduced the surface roughness and porosity value to 1.8 and 1.4 times respectively while the use of the coarser sized one reduced these values to 1.3 and 1.2 times respectively compared to the pure Al2O3 coated surface. 8-times higher hardness and 70-times lower wear rate values compared to the substrate were the most significant improvements observed in the pure Al2O3 coated surface among all coated samples. Although TiO2 addition to the coating powder decreased hardness by 1.1 times and increased wear rate by 1.8 times, spraying finer TiO2 added coating powders resulted in a slight improvement in both hardness and wear resistance compared to the coarser one.
Dynamic Strain Aging Behaviour in AISI 316L Austenitic Stainless Steel under As-Received and As-Welded Conditions
(Mdpi, 2017) Muhamed, Guma Alnaji; Gunduz, Suleyman; Erden, Mehmet Akif; Tastemur, Demet
In the current study, dynamic strain ageing (DSA) phenomena in 316L austenitic stainless steel was investigated under as-received and as-welded conditions. A tensile test was carried out on as-received and as-welded samples for the temperatures of 25-800 degrees C at a strain rate of 1 x 10(-3) s(-1). Microstructure and fracture surfaces were investigated by optic and scanning electron microscopes (SEM). 316L austenitic stainless steel showed different DSA behavior under as-received and as-welded conditions, which are discussed in terms of microstructure and mechanical properties.
Effect of c content on microstructure and mechanical properties of nb-v added microalloyed steel produced by powder metallurgy method
(2016) Erden, Mehmet Akif
In this work, the effect of C content on the microstructures and tensile behaviors of Nb-V added microalloyed powder metallurgy (PM) steels were investigated. The samples pressed at 700 MPa and sintered at 1450°C temperature in the sintering argon atmosphere for 1 h were produced. Nb-V added PM microalloyed steels with different carbon ratio were analyzed in terms of tensile test. Results indicated that the images of microstructure that as the proportion of the C in the PM samples increases, the volume of the perlite gets increase gradually and 0.35 wt. % C added Nb-V PM steel showed the highest values in yield strength (YS) and ultimate tensile strength (UTS).
The effect of cr and ni addition on mechanical properties of plain carbon steel
(2019) Demırtaş, Hüseyin; Erden, Mehmet Akif
In this study, the effect of Cr-Ni addition on the mechanical properties of plain carbon steel was investigated. Forthis purpose, Cr-Ni (wt. % 0.5-3) was added to the matrix containing 0.5 C with powder metallurgy method. Thetensile test, micro hardness measurement and microstructure analysis were performed to investigate the effect ofthe additions on the mechanical properties. As a result, it was determined that the added alloying elementsincreased the mechanical properties, but the mechanical properties decreased with the amount of alloyingelements increasing after 1% wt. due to the powder metallurgy process.
Effect of Cr Limits on Microstructure and Mechanical Properties of P/M 316L Austenitic Steel
(Int Inst Science Sintering (I I S S), 2024) Erden, Mehmet Akif; Demirtas, Hueseyin; Oleiwi, Fadhil Hussein
This study investigated the effect of the Cr limits on the microstructure and mechanical properties of 316L alloy. Five 316L alloys with varying Cr contents (16.8, 17.1, 17.3, 17.8 and 18.8 wt.%) were produced by the powder metallurgy (P/M) method. Microstructure studies and phase analysis were performed with a scanning electron microscope (SEM), optical microscopy (OM), and energy dispersive spectrometry (EDS). Tensile tests and hardness measurements were performed to evaluate the hardness, strength, and ductility of the alloys. The results showed that Cr addition affected the porosity and grain size of the alloys, as well as the formation of precipitates. The ultimate tensile strength reached a maximum at 17.3 wt.% Cr and then decreased with further Cr addition. Ductility decreased with increasing Cr under the influence of precipitates formed and changes in microstructure. On the other hand, the hardness increased with increasing Cr inversely to the ductility.
Effect of Different Current Values on Microstructure and Mechanical Properties of Microalloyed Steels Joined by the Submerged Arc Welding Method
(Mdpi Ag, 2016) Karabulut, Hasan; Turkmen, Mustafa; Erden, Mehmet Akif; Gunduz, Suleyman
In this study, microalloyed steels were joined by using the submerged arc welding method at different welding currents of 350 A, 400 A and 450 A. The effects of selected welding parameters on the microstructure and mechanical properties of welded materials were investigated. Tensile tests and microhardness measurements were performed. Microstructural changes have been identified in the welding zone. The results showed an increase in hardness and tensile strength depending on the current intensity. The heat affected zone was observed much wider with the increase in welding current.
The Effect of Mn and Ti Ratio on Microstructure and Mechanical and Machinability Properties of 316 L Stainless Steel Used in Biomedical Applications
(Mdpi, 2023) Turkmen, Mustafa; Tanouz, Alla Muhammed; Akgun, Mahir; Erden, Mehmet Akif
In this study, titanium (Ti) and manganese (Mn) element powders in determined amounts (0.35-0.75 and 1.5 wt %) were added into the 316 L stainless steel matrix by means of powder metallurgy (PM) technology, either individually or in pairs, and the desired composition was obtained as a powder mixture. The powders used in the study were cold-pressed tensile sample molds prepared in ASTM E8M standards, unidirectionally cold-pressed under 750 MPa compression pressure and formed into blocks. After pressing, the raw strength samples were sintered in an atmosphere-controlled tube furnace at 1250 degrees C for two hours in an argon atmosphere. The microstructure and mechanical properties of the produced PM steels were characterized using an optical microscope, SEM, EDS, tensile test, and hardness test. The results showed that the stainless steel samples with 0.35 (Ti and Mn) added to 316 L stainless steel had the highest yield strength, tensile strengths, and hardness strengths. However, with the addition of 0.75-1.5 Ti, 0.75-1.5 Mn and 0.75-1.5 (Ti and Mn) to 316 L stainless steel, a decrease was observed in the mechanical properties. Moreover, the stainless steel sample with 0.35 (Ti and Mn) added to 316 L stainless steel is better than other samples in terms of surface quality.
The Effect of Ni on the Microstructure and Mechanical Properties of Nb-V Microalloyed Steels Produced by Powder Metallurgy
(Gazi Univ, 2016) Erden, Mehmet Akif; Tasci, Muhammed Taha
In this work, the effect of Ni (wt. % 2-3-5) on the microstructures and tensile behaviours of Fe matrix metarials including graphite 0.55 wt. % and (Nb-V) 0.15 wt. % were investigated. The samples pressed at 750 MPa were produced by sintered at 1350 degrees C temperature in the argon atmosphere for 1 h. The microstructure of the producted PM steels was characterised by optic microscope, SEM and EDS. Results indicated that 5 wt. % Ni added PM steel showed the highest values in yield strength (YS) and ultimate tensile strength (UTS).
The Effect of Nickel on the Microstructure, Mechanical Properties and Corrosion Properties of Niobium-Vanadium Microalloyed Powder Metallurgy Steels
(Mdpi, 2020) Ahssi, Mohamed Ahmed Mohamed; Erden, Mehmet Akif; Acarer, Mustafa; Cug, Harun
In this study, the effects of adding Ni in different ratios to Fe-matrix material containing C-Nb-V produced by powder metallurgy on microstructure, tensile strength, hardness and corrosion behaviors were investigated. Fe-C and Fe-C-Nb-V powders containing 5%, 10%, 13%, 15%, 20%, 30% and 40% nickel were pressed at 700 MPa and then sintered in an Ar atmosphere at 1400 degrees C. Microstructures of the samples were characterized with optical microscope, scanning electron microscope (SEM) and XRD. Corrosion behaviors were investigated by obtaining Tafel curves in an aqueous solution containing 3.5% NaCl. Mechanical properties were determined by hardness and tensile testing. While Fe-C alloy and Fe-C-Nb-V microalloyed steel without Ni typically have a ferrite-pearlite microstructure, the austenite phase has been observed in the microstructures of the alloys with 10% nickel and further. Yield and tensile strength increased with nickel content and reached the highest strength values with 13% Ni content. The addition of more nickel led to decrease the strength. Analysis of Tafel curves showed that corrosion resistance of alloys increased with increasing nickel concentration.
EFFECT OF THE ADDITION OF NIOBIUM AND ALUMINIUM ON THE MICROSTRUCTURES AND MECHANICAL PROPERTIES OF MICRO-ALLOYED PM STEELS
(Inst Za Kovinske Materiale I In Tehnologie, 2016) Gunduz, Suleyman; Erden, Mehmet Akif; Karabulut, Hasan; Turkmen, Mustafa
In this work, the effects of the addition of Nb and Al on the microstructures and tensile behaviours of micro-alloyed powder metallurgy (PM) steels were investigated. The microstructure of the micro-alloyed PM steels was examined by light microscope, SEM, XRD, XRF and EDS. The results indicated that the addition of (0.1, 0.15 or 0.2) % of Nb-Al increases the yield strength (YS) and the ultimate tensile strength (UTS) of the PM sintered steels. Elongation also tends to improve with an increasing Nb and Al content. In addition, the Nb and Al limit the grain growth during austenitization.
The Effect of the Sintering Temperature and Addition of Niobium and Vanadium on the Microstructure and Mechanical Properties of Microalloyed PM Steels
(Mdpi, 2017) Erden, Mehmet Akif
In this work, the effect of the sintering temperature on the microstructure and mechanical properties of Nb-V added powder metallurgy (PM) steels was investigated. The microstructure and mechanical properties of the Nb-V added PM microalloyed steel were examined by optical microscopy, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), optical emission spectrometer (OES), tensile and hardness tests. Results indicated that the optimal sintering temperature was 1350 degrees C and the addition of 0.1%, 0.15% or 0.2% of Nb-V increases the yield strength (YS), ultimate tensile strength (UTS) and hardness of the PM sintered steels. 0.2 wt % Nb-V added PM steel showed the highest values in yield strength (YS), ultimate tensile strength (UTS) and the highest hardness. Elongation also tends to improve with adding Nb-V content. In addition, Nb-V limited grain growth during austenitization.
Effect of TiC, TiN, and TiCN on Microstructural, Mechanical and Tribological Properties of PM Steels
(Int Inst Science Sintering (I I S S), 2021) Erden, Mehmet Akif; Tasliyan, Mehmet Furkan; Akgul, Yasin
Developments in sintering of powder mixtures contributed growth of steel production via powder metallurgy. This study aims to improve the mechanical and tribological properties of carbon steels produced via powder metallurgy. For this purpose, P/M carbon steel was alloyed with 3 % Manganese. Then, this alloyed steel was reinforced with particles such as titanium carbide (TiC), titanium nitride (TiN) and titanium carbonitride (TiCN) in different proportions (0.5 and 1 %) and combinations. The effect of these additives on the mechanical properties of PM steels was determined by conducting tensile and hardness tests. Wear tests were performed to understand the tribological properties of samples. Also, microstructural properties, fracture surfaces, and worn surfaces of samples were examined using a Scanning Electron Microscope. Results show that the hardness and tensile strength of carbon steel increased by nearly 158 % and 62 % respectively, while the wear resistance improved by 4 times with the addition of 3 % Mn and 0.5 % TiCN.
Effect of vanadium addition on the microstructure and mechanical properties of low carbon micro-alloyed powder metallurgy steels
(Carl Hanser Verlag, 2016) Erden, Mehmet Akif; Gunduz, Suleyman; Karabulut, Hasan; Karabuk; Turkmen, Mustafa
In the present experimental work, the effects of vanadium additions on the microstructures and mechanical properties of powder metallurgy (PM) steel and microalloyed powder metallurgy (PM) steels were investigated. The microstructures of the PM steel and microalloyed PM steels were characterized by optic microscope, SEM and EDS. Experimental results showed that vanadium microalloyed steels can be produced by PM technology. The addition of vanadium limits grain growth during austenitization prior to air cooling and increases the strength in the sintered conditions. By limiting austenite grain growth, the precipitates result in significant improvement in strength.
Effects of compaction pressure on microstructure, mechanical properties, and machining characteristics of sintered AISI 316L steel
(Walter De Gruyter Gmbh, 2024) Erden, Mehmet Akif; Koklu, Ugur; Guldibi, Ahmet Serdar; Elitas, Muhammed
In this study, the effect of compaction pressure on the properties of AISI 316L and its machining performance was evaluated. AISI 316L powders were subjected to three different compaction pressures (550, 650, and 750 MPa). Subsequently, the samples were sintered in an argon atmosphere at a constant temperature of 1523.15 K. The microstructure, hardness, and mechanical properties of the materials were investigated. To examine the effect of compaction pressure on drilling characteristics (thrust force, torque, surface roughness, chip formation, and burr formation), the samples were subjected to dry drilling at different feed rates and cutting speeds. It was observed that increasing the compaction pressure resulted in smaller grain sizes in the microstructure, increased hardness, and higher tensile strength. Higher compaction pressure led to higher thrust force and torque, whereas lower compaction pressure resulted in improved hole surface quality and shorter chips. Additionally, at higher cutting speeds, the color of the chips changed due to the elevated temperatures associated with increased cutting speeds.
The Effects of Hot Rolling Process on Mechanical Properties, Corrosion Resistance, and Microstructures of Mo-Ni Alloyed Steels Produced by Powder Metallurgy
(Int Inst Science Sintering (I I S S), 2024) Elkilani, Rajab Hussein Rajab; Cug, Harun; Erden, Mehmet Akif
This study examined the effects of hot rolling on the microstructure, tensile strength, and corrosion behaviors of three different alloy steels made by powder metallurgy: Fe -0.55C, Fe-0.55C-3Mo, and Fe-0.55C-3Mo-10Ni. 700 MPa pressure was applied to press the particles. The cold pressed samples were sintered in a mixed -gas atmosphere (90% nitrogen, 10% hydrogen) at 5 degrees C/min up to 1400 degrees C for 2 hours. Then, the produced steels were hot rolled with a deformation rate of 80%. The microstructures show that deformed Mo and MoNi steels have finer microstructures, better mechanical properties than undeformed Mo and Mo-Ni steels, and MoC, MoN, or MoC(N) was formed in the Mo-Ni steels. The highest mechanical properties were obtained in rolled steel samples containing Mo-Ni, followed by rolled Mo steel and rolled carbon steel samples, and then unrolled samples. Additionally, Tafel curve analysis demonstrated that alloy corrosion resistance rose as Ni concentration increased. It has also been observed that the hot rolling process improves corrosion resistance. The increase in the density value with the rolling process emerged as the best supporter of corrosion resistance.
Evaluation of the mechanical properties and machinability of chromium and molybdenum-added powder metallurgy steels
(Sage Publications Ltd, 2024) Vassouf, Abdul Rahman; Akgun, Mahir; Erden, Mehmet Akif
The present study focuses on the microstructure, mechanical properties, and machining aspects of powder metallurgy (PM) steel containing different rates of chromium (Cr) and molybdenum (Mo). PM steel alloys were pressed at 700 MPa and sintered at 1400 degrees C in a mixture of nitrogen and hydrogen atmosphere for 1 hour. While the precipitates and fracture surfaces of the samples obtained were examined by scanning electron microscope (SEM) and EDS analyzes, the grain size and phase distributions were also examined with an optical microscope. Moreover, tensile and hardness measurement tests were carried out to determine the mechanical properties of the samples with different ratios of Cr and Mo content. The milling experiments were also performed without using coolant in a CNC milling machine at different cutting parameters. The surface roughness (Ra), tool wear (Vb), and wear mechanism were investigated under these conditions. The outcomes of this study reveal that the yield and tensile strength values of the samples with the addition of Cr and Mo increased but the elongation value decreased. The results also stated that the most effective process parameter for both Vb and Ra was the workpiece material and the regression models developed to estimate the output parameters (Vb and Ra) give successful results with high determination coefficients (R-2) of 98.05% and 98.11%, respectively.
Hydrothermal carbon effect on iron matrix composites produced by powder metallurgy
(Elsevier Science Sa, 2020) Simsir, Hamza; Akgul, Yasin; Erden, Mehmet Akif
In this work, hydrothermal carbons (HTC) were obtained from glucose at 200 degrees C for 30 h. HTC and its calcinated product (HTC*) were added to pure iron powder with different ratios (0.25, 0.50 and 0.75 wt%) to obtained HTC reinforced iron composites by powder metallurgy. To our knowledge, this is the first study that investigates the effect of HTC on iron matrix composites. Microstructure, hardness, compression and corrosion behaviors of composites were investigated. According to the results, mechanical properties of composites were enhanced with the increasing of HTC/HTC* amount. However, high corrosion resistances were gained with the using of the low amount of HTC (0.25 and 0.50 wt%) and HTC* (0.25 wt%).
Influence of carbon fiber content on bio-tribological performances of high-density polyethylene
(Iop Publishing Ltd, 2019) Akgul, Yasin; Ahlatci, Hayrettin; Turan, Muhammet Emre; Erden, Mehmet Akif; Sun, Yavuz; Kilic, Ali
The present study aims to investigate the effect of short carbon fiber (SCFs) content on wear performance of high-density polyethylene (HDPE). SCFs reinforced composites with different weight fractions (5 wt%, 10 wt%, 15 wt% and 20 wt%) were fabricated by melt compounding and compression molding. To evaluate bio- tribological performance of the samples, three different loads (20 N, 40 N and 60 N) were applied to simulate body fluid (SBF) environment against stainless steel counterface. The scanning electron microscope was used to investigate the morphology of composite granules and worn surfaces of samples. Also, the hardness test was conducted for all samples. The results show that the hardness of high-density polyethylene increases significantly depending on the short carbon fiber content. 20 wt% SCFs reinforced composite exhibited the highest hardness, which is 34% improvement compared to the pure HDPE. However, the same trend was not observed for wear resistance of composites. Composites containing 10 wt% SCFs showed best wear performance in SBF fluid conditions.
Influence of NbC Addition on the Sintering Behaviour of Medium Carbon PM Steels
(Mdpi Ag, 2017) Ozdemirler, Dogan; Gunduz, Suleyman; Erden, Mehmet Akif
In this work, the effects of NbC additions on the microstructure and mechanical properties were examined. In order to do this, NbC compounds were added into the Fe matrix at the weight percentage of 0.1-2 with individually to obtain powder mixture. The microstructure of the powder metallurgy (PM) steels were characterized by optic microscope, scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). Experimental results indicated that NbC alloyed steels can be produced by PM technology. An increase in strength was observed when the amount of NbC compounds increased for all PM steels. The precipitation of carbides and nitrides in these steels limits austenite grain growth and increases the precipitation hardening or clustering hardening that results in significant improvement in strength.
Influence of the heat treatment on the microstructure and machinability of AISI H13 hot work tool steel
(Springer London Ltd, 2018) Demir, Halil; Gunduz, Suleyman; Erden, Mehmet Akif
In this work, the influence of heat treatment on the microstructure and machinability of AISI H13 tool steel was investigated for the as-received (AR), water-quenched (Q), quenched and single-tempered (QST) and quenched and double-tempered (QDT) conditions. The machining tests were carried out through turning method at various cutting speeds. The results indicated that heat treatment conditions and the cutting speed affected the surface roughness of samples. However, cutting forces were not affected by steel microstructure and cutting speed except to those of water-quenched samples.

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