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The main objective of this study is to examine the machinability and the surface quality conditions of the AA7075 material with different temper conditions. For this purpose, various temper treatments are implemented to evaluate the impact of microstructural properties on tool wear and the surface quality of the drilled holes. The drilling operations have been done on 0, F, T4, T6, and T7 temper conditions. Process parameters were three different spindle speeds (715, 1520, and 3030 rev/min) and three feed rates (0.1, 0.2, and 0.3 mm/rev) with HSS-G high-performance ground standard twist drill bit. The present work deals with the effects of temper conditions on thrust force, drilling temperature, tool wear, surface integrity, and chip morphology. Response surface methodology was used in the evaluation of experiment results. The optimization results showed that while thrust force and torque are not significantly affected by a change in spindle speed, they are sensitive to an increase in feed rate. Heat-generation on the drill bit is the lowest at low levels of both the feed rate and spindle speed parameters. The AA7075-T6 condition specimen was machined with continuous chip formation, resulting in the best hole surface quality. The 3D finite element modeling of the drilling process was carried out, and the drilling performance of AA7075-T6 was evaluated in terms of thrust force, heat generation, and chip formation.

The present study reveals for the first time the dry sliding wear behavior of a powder metallurgical pure titanium alloy (Cp-Ti) modified by shot peening. Cp-Ti samples were manufactured via powder metallurgy, and then their surface and subsurface features were modified using a custom-made, fully automated shot-peening system. The texture isotropy rate and the highest orientation angle of the shot-peened samples were 71.5% and 36°, respectively. The Abbott curves of the shot-peened surfaces revealed that the most common areal roughness value was 5.177 μm, with a frequency of 8.1%. Shot-peened surfaces exhibited an ~20% lower wear rate than unpeened surfaces under dry sliding wear, whereas the coefficient of friction was the same for both surfaces. Micro-ploughing, micro-cutting, oxidation, and three-body abrasion wear mechanisms were observed on the shot-peened and unpeened surfaces. High resolution 3D surface topographies of worn unpeened and shot-peened surfaces revealed micro-scratches and inhomogeneities along wear tracks, which are indicative of three-body abrasion mechanisms during contact. In addition, vertical and horizontal microcracks were visible just beneath the wear track, suggesting a clear indication of plastic deformation during contact. The cross-sectional hardness maps of shot-peened samples revealed the formation of a work-hardened surface layer with shot peening, which improved the wear resistance. These findings support that shot peening can be a useful tool to modify the surface and tribological properties of powder metallurgical Cp-Ti alloys.

AA7075 is one of the most suitable materials for aerospace, aircraft, and defense applications with its high yield strength and low-density. In many other modern machining methods, conventional drilling remains the most extensive material removal process in industrial components. The main objective of this study is examining the machinability and surface quality conditions of the AA7075 material with different temper conditions. For this purpose, various temper treatments are implemented to evaluate the impact of microstructural properties on tool wear and surface quality of the drilled holes. The drilling operations have been done on O, F, T4, T6, and T7 temper conditions. Process parameters were three different spindle speeds (715, 1520, and 3030 rev/min) and three feed rates (0.1, 0.2, and 0.3 mm/rev) with HSS-G high-performance ground standard twist drill bit. The present work deals with the effects of temper conditions on thrust force, drilling temperature, tool wear, surface integrity, and chip morphology. Drilling performance is related to the intrinsic microstructural properties of temper conditions. Response surface methodology was used in the evaluation of experiment results. The optimization results showed that while thrust force and torque are not significantly affected by change in spindle speed, they are sensitive to increase in feed rate. Heat-generation on the drill bit is the lowest at low levels of both the feed rate and spindle speed parameters. Among different temper conditions, the AA7075-T6 condition sample is processed with continuous chip formation and resulted in the best hole surface quality. The 3D finite element modelling of the drilling process was carried out, and the drilling performance of AA7075-T6 was evaluated in terms of thrust force, heat generation, and chip formation.

In this study, the effect of cooling rate on microstructure, mechanical properties and residual stress of 7075 aluminum alloy was investigated. The influence of cooling rate on microstructure, hardness, electrical conductivity of 7075 aluminum alloy was investigated using a Jominy end quench test. Water at three different temperatures (20 °C, 50 °C, 75 °C) and polymer solutions of varied concentrations (5vol.-% and 25vol.-%) were used as a quenching medium. The changes of hardness, electrical conductivity and microstructure properties of the specimens with an increase in distance from the quenched surface were investigated comparatively for different quenching mediums. Tensile tests were applied to determine the effect of the quenching rate on mechanical properties of the specimens. Residual stress was measured using the ESPI hole drilling technique to understand the influence of cooling rate. The results show that the cooling rate decreases as the distance from the quenched surface, water temperature and polymer concentration increases. The changes in material properties such as hardness, electrical conductivity along the material profile decrease as water temperature and polymer concentration increase. Although the hardness and mechanical properties of the material decrease as the cooling rate decreases, the values obtained are convenient for conditions of industrial usage. Residual stress was significantly eliminated by quenching in hot water or polymer solution at a high concentration.

High alloy white cast iron materials (Ni-Hard 4/ASTM A532) are widely used in cement, concrete and mining industries due to high wear resistance. In this study, the effect of boron on the microstructure, mechanical properties and wear resistance in white cast iron containing different contents of boron was investigated. For this purpose, ferro-boron was used during cast that boron will occur with the contents of 0.26%, 0.37%, 0.49% and 0.55% in the material. Specimens were austenitized at 850 °C for 5 h, quenched in air and tempered at 250 °C for 4 h. Wear tests were carried out using a pin-on-disc tribometer under dry sliding conditions. Three-point bending tests were performed to determine the toughness properties. Microstructure, fracture and worn surfaces were investigated with scanning electron microscope. The results show that amount of carbide increases as boron content increases. This situation provides positive contribution on materials hardness and wear resistance. Toughness properties decrease as the boron content increases.

In this paper, the effect of nickel content on the mechanical properties of aluminum were investigated. High purity Al and Ni were melted in an induction furnace and cast into a metal mold. Microstructural characteristic and mechanical properties of the alloys were studied in detail. The addition of nickel to pure aluminum increased the tensile strength and decreased the elongation at break value of the specimens. Maximum wear resistance was obtained with the addition of 3 wt.-% Ni. Further addition of nickel caused a decrease in wear resistance.

In this study, the effect of homogenization treatment on the microstructure, toughness and wear resistance of plastic mold steel was investigated. Homogenization heat treatment was performed at 1150 °C for 3 hours. All specimens were austenitized at 850 °C for 1 hour, quenched in oil and tempered at different temperatures. Wear tests were carried out using a pin-on-disc tribometer under dry sliding conditions. Charpy V notch impact tests were performed to determine the toughness properties. Microstructure, fracture and worn surfaces were investigated by scanning electron microscope. The results show that heat treatment conditions have an effect on the microstructure and mechanical properties of materials. It was determined that homogenization heat treatment causes more homogeneous structure, in particular, it has a positive effect on the toughness properties and wear resistance of the materials which were tempered at low temperatures.

Yüksekalaşımlı beyaz dökme demir malzemeler yüksek aşınma dayanımından dolayıçimento, beton ve madencilik sektörlerinde geniş bir kullanım alanına sahiptir.Bu çalışmada, yüksek alaşımlı beyaz dökme demir malzemelerde titanyumkatkısının mikroyapı ve sertlik özelliklerine etkisi incelenmiştir. Bu amaçla,döküm malzemeler % 0.5, % 1 % 1.5 ve % 2oranlarında titanyum içerecek şekilde indüksiyon ocağında ergitilerekalaşımlandırılmış ve metal kalıba dökülerek şekillendirilmiştir. Farklıoranlarda titanyum içeren numunelere 850 ˚C’ de 5 saat süreyle tavlamayapılarak havada sertleştirilmiş ve devamında 250 ˚C’ de 4 saatsüreyle temperleme işlemi uygulanmıştır. Döküm konumundaki ve ısıl işlemuygulanmış numunelerde ışık mikroskobu ve elektron mikroskobu (SEM) ilemikroyapı incelemeleri yapılmıştır. Artan titanyum oranı ve ısıl işlem koşullarına bağlı olarak malzemelerinmikroyapı ve sertlik özelliklerinde meydana gelen değişimler karşılaştırmalıolarak incelenmiştir., High alloy white cast iron materials are widely used in cement, concrete and mining industries due to high wear resistance. In this study, the effect of titanium on microstructure and hardness properties in white cast iron materials was investigated. For this purpose, cast materials were alloyed by melting at in induction furnace to include titanium with the rates of % 0, % 0.5, % 0.1, % 1.5, % 2 and were formed by casting into the metal mould. Specimens with different contents of titanium were applied hardening on air after heat treatment at 850 ˚C for 5 hours and tempered at 250 ˚C for 4 hours. Microstructure of cast and heat treated specimens were investigated by using light microscope and scanning electron microscope (SEM). In the microstructure investigations, it was observed that titanium has a significant effect on carbide morphology. It was seen that the hardness of the material with heat treatment increases significantly according to the casting condition. Also it was observed that highest hardness values were obtained with the specimens that include %1 Ti.

In this study, aluminium–nickel alloys with different Ni ratios ranging from 1 to 5 wt-% were produced by casting method. The effect of nickel on the microstructure and hardness properties was studied. The dry sliding wear response of the Al–xNi alloys against steel and alumina counterfaces was investigated. Worn surfaces of the alloys were examined using scanning electron microscopy. The results showed that the hardness of the alloys increases with increasing nickel content. Severe wear damage was observed at low and high nickel contents. Maximum wear resistance was obtained with the addition of 3 wt-% nickel to the pure aluminium under both loads and against both counterfaces.

Al-Zn-Mg-Cualüminyum alaşımları sahip oldukları düşük yoğunluk, yüksek mukavemet, sertlik,tokluk ve korozyon direnci özelliklerinden dolayı havacılık ve uzayendüstrisinde geniş bir kullanım alanına sahiptir. Bu çalışmada, 7075 serisi alüminyum alaşımınınsu verme hassasiyeti alın su verme yöntemi kullanılarak incelenmiştir. Numuneye480 °C’de 3 sa. süreyle çözeltiye alma işlemi uygulandıktan hemen sonra alın suverme test düzeneğinde oda sıcaklığındaki su ile bir uçtan soğutma işlemiuygulanmıştır. Soğutma işlemi esnasında numunenin boyuna kesiti boyunca meydanagelen soğuma hızındaki değişimler K tipi termo-elemanlar vasıtasıyla eş zamanlıolarak ölçülmüştür. Su verme işlemi sonrası numuneye 120 °C’de 24 sa. süre ilesuni yaşlandırma işlemi uygulanmıştır. Su verilen uçtan uzaklaştıkça malzemeninsertlik, elektriksel iletkenlik ve mikroyapı özeliklerinde meydana gelendeğişimler incelenmiştir., Al-Zn-Mg-Cualuminum alloys are extensively used in aviation and aerospace industries fortheir high strength, hardness, toughness and corrosion resistance. In thisstudy, quench sensitivity of 7075 series aluminum alloy was investigated byusing end quench test. Specimens were solution treated at 480 °C for 3 hoursand then the specimens were immediately transferred to the end quenching rig(

Koc, Funda Gul/0000-0001-6517-1239; WOS: 000375628600012 High-alloyed white-cast-iron materials are commonly used in the manufacturing industry due to their high wear resistance. The aim of this research is to determine the cutting tool and the optimum cutting conditions required for the metal cutting of these materials. In this study, it is proposed to determine the wear and the tool life utilizing the Taguchi optimization method when hard turning the Ni-Hard 4 material, the alloyed cast iron, with cutting tools produced with powder metallurgy (PM) and to improve the performance of the cutting tools. A series of 18 experiments were conducted on a CNC turning machine, using the cutting process parameters such as the cutting speed, the feed and the depth of cut, based on the Taguchi L-9 orthogonal design of experiments. Uncoated cutting tools were utilized to perform these experiments. PM cutting tools with WC grain sizes of 0.8 mu m and 1.25 mu m were selected for the hard-turning experiments. The flank wear of the cutting tools was examined with SEM. Then, the life of each cutting tool was identified based on the cutting length. The performance of the cutting tools in terms of the wear and the tool life was determined with the Taguchi method based on the obtained data. The results of this study contributed to the hard turning of the Ni-Hard 4 material that is mostly employed in the as-cast condition in the manufacturing industry due to its high hardness. The optimum cutting conditions were determined by means of the Taguchi method. Scientific Research Project Unit of the Kocaeli University [KOU-BAP-2012/72] The authors would like to thank Ugur Yucel at the University of Kocaeli and ARMEKSAN, Machine Part Industry Corporation. This study was supported by the Scientific Research Project Unit of the Kocaeli University (KOU-BAP-2012/72).