Effect of microstructure on mechanical properties and abrasive wear behavior of low carbon dual-phase steels

The mechanical properties and wear behavior of Dual Phase (DP) steels have been investigated and compared with those observed in normalized (N) steel that has the same chemical composition. The DP steels having different content and morphology of martensite were produced by varying intercritical annealing temperature and initial microstructures. Mechanical properties of four different DP steels and N steel have been investigated by carrying out tensile and macrohardness tests. Dry sliding wear tests have been conducted on four different the DP steels and the N steel using pin-on-plate to investigate their wear characteristics. It has been found that the yield and tensile strengths and macrohardness increase with increasing martensite content and decreasing martensite size. The yield and tensile strengths and macrohardness of the N steel were significantly lower than the DP steels whereas percentage of total elongation was higher. Wear properties are improved by increasing martensite volume fraction and size in the DP steels. The N steel specimen showed the highest wear rate

Design and analysis of lightweight automotive component for turbocharger units

Nowadays global warming in parallel with air pollution is a significant problem. One of the major causes is the conventional fuel-powered automobile. This study focuses on reducing global warming caused by automobiles. This paper presents the results of redesign and analysis of piping component of a turbocharger unit from a new material in order to reduce the weight and unify the component from only one material. The existing component is composed of three different parts and materials. With the new design, in addition to the lightweight property, the component is designed in such a way that two separate parts of existing design are unified in a single part which simplifies the assembly of the component to the turbocharger unit. The design starts with choosing the convenient material to satisfy the necessary service conditions such as high temperature and pressure. Two different materials are considered for the analyses which are aluminium alloy and PA66+PA6-HI glass fiber reinforced plastic matrix composite material. Firstly, finite element analyses were performed by using a commercial software. The results of the finite element analyses showed that both materials showed resistance to tensile load of 4000 N and pressure of 0.4 MPa at 22°C. However, if two separate parts were unified with a single part made of aluminium alloy, this component would fail under pressure of 0.4 MPa at 150°C and 210°C, while the component made of PA66+PA6-HI glass fiber reinforced plastic matrix composite material resisted the pressure at higher temperatures. Tensile tests under 4000 N and pressure tests under 0.4 MPa at temperatures of 22°C, 150°C and 210°C were carried out on the component produced by PA66+PA6-HI glass fiber reinforced plastic matrix composite material. The same results were observed with those obtained by the finite element analyses. The design with the composite material satisfies both the mechanical and lightweight considerations.This work is supported by TUBITAK-Turkish Scientific and Technological Research Council under the project number: 7130723

Sprey döküm

Bu makalede sprey döküm yöntemi incelendi. Sprey dökümün özet olarak tarihsel gelişimi ve proses hakkında bilgi verildi. Daha sonra sprey dökümle üretilmiş alaşımların metalurjik özellikleri, proses parametreleri ve sprey döküm yönteminin katılaşma mekanizması detaylı olarak tartışıldı. Son olarak bazı sprey dökülmüş Al-Zn-Mg-Cu alaşımlarının mikroyapı ve mekanik özellikleri verildi ve bu sonuçlar geleneksel döküm yöntemi ve toz metalurjisiyle üretilmiş 7xxx serisi alüminyum alaşımlarının özellikleri ile kıyaslandı.This paper is designed to provide a basic review of spray casting. A brief overview of the historical development of spray casting and the description of plant and equipment have been given. Following metallurgical characteristics of spray formed alloys, process parameters and solidification mechanism of spray deposition have been discussed in detail. Finally, microstructure and mechanical properties of the selected spray cast Al-Zn-Mg-Cu alloys have been presented and compared with conventionally and powder metallurgy processed 7xxx aluminium alloys

Sprey dökülmüş Al-Zn-Mg-Cu alaşımlarının yaşlanma davranışı

Bakır, çinko ve magnezyum içeren 7xxx serisi alüminyum alaşımları SS70, N707 ve 7075 hızlı katılaştırma yöntemi olan sprey dökümle üretildiler. 7075 alaşımının 175°C, 130°C ve 120°C de yaşlandırılması sonucunda sırasıyla 2, 24 ve 48 saat sonra maksimum sertlik değerlerine ulaşıldı. Bu değerler sırasıyla 147, 186 ve 191 MPa dır. Diğer iki alaşım SS70 ve N707'in 120° C de yaşlandırılmasında maksimum sertliğe 24 saat sonra ulaştılar. SS70'in ulaştığı maksimum sertlik 229 MPa ve N707'in ulaştığı değer 228 MPa dır. 7075 alaşımı 105° C de 5 saat yaşlandırmadan sonra 175° C de 1 saat yaşlandırma şeklinde uygulanan çifte yaşlandırma sonucunda 185,6 MPa sertlik değerine ulaştı. Bu değer 7075 alaşımına 175°C de uygulanan yaşlandırmayla elde edilen sertlikten daha yüksektir. Yaşlandırılmış alaşımlardan hazırlanan TEM numunelerinin incelenmesi sonucunda sertleşmeyi $\eta^{'}$ ve $\eta$ çökeltilerinin sağladığı ortaya çıkarıldı.Three 7xxx series aluminium SS70, N707 and 7075 alloys containing copper, zinc and magnesium were spray deposited using rapid solidification. Ageing of the 7075 alloy resulted in a peak hardnesses of 147, 186 and 191 MPa after 2, 24 and 48 h at temperatures of 175oC, 130oC and 120oC respectively. The other two alloys, SS70 and N707, were aged at 120oC, and both reached peak hardness after 24 h; SS70 had a peak hardness of 229 MPa and N707 of 228 MPa. A double ageing treatment at 105oC for 5 h then at 175oC for 1 h significantly increased the peak hardness to 185.6 MPa compared to a single stage of ageing at the higher temperatures in the 7075 alloy. TEM analysis of aged specimens revealed two types of precipitate that contributed to age hardening: $\eta^{'}$ and $\eta$ (MgZn2)

Mechanical properties of spray cast 7XXX series aluminium alloys

Mechanical properties of spray deposited and extruded 7xxx series aluminium alloys were investigated in peak aged condition. To study the influence of Zn additions on the mechanical behaviour of spray deposited materials, three alloy compositions were selected, namely: SS70 (11.5% Zn), N707 (10.9% Zn) and 7075 (5.6% Zn). After ageing treatment, notched and unnotched specimens of spray deposited alloys were subjected to tensile tests at room temperature. Experimental results showed that the SS70 alloy exhibited the highest strength. Spray deposited Al alloys showed a very high strength as compared to conventionally processed 7xxx series Al alloys. Compared with the PM processed 7xxx series Al alloys, fracture toughness values of these alloys were higher.Mechanical properties of spray deposited and extruded 7xxx series aluminium alloys were investigated in peak aged condition. To study the influence of Zn additions on the mechanical behaviour of spray deposited materials, three alloy compositions were selected, namely: SS70 (11.5% Zn), N707 (10.9% Zn) and 7075 (5.6% Zn). After ageing treatment, notched and unnotched specimens of spray deposited alloys were subjected to tensile tests at room temperature. Experimental results showed that the SS70 alloy exhibited the highest strength. Spray deposited Al alloys showed a very high strength as compared to conventionally processed 7xxx series Al alloys. Compared with the PM processed 7xxx series Al alloys, fracture toughness values of these alloys were higher

Enhancing mechanical properties of bolted carbon/epoxy nanocomposites with carbon nanotube, nanoclay, and hybrid loading

The effects of adding nanoclay (NC), carbon nanotube (CNT), and a hybrid of both on bending, tensile and bearing strengths of nanocomposite plates were investigated in this study. Sonication method was used to ensure dispersion of the nanoparticles in epoxy homogeneously. The nanocomposite plates were produced by a vacuum assisted resin transfer molding (VARTM) process. Mechanical properties were investigated by applying bending and tensile testing as well as tensile test with bolted joints on the nanocomposite plates. According to the bearing strength, 5.2%, 3.9%, and 0.8% improvements were obtained in NC, CNT and hybrid (NC + CNT) loaded specimens respectively while much more improvement range from 47.7% to 57.1% was obtained in tensile strength. In addition, the impact of nanoparticle loading on the porosity was determined by applying the burning test and its effect on the mechanical properties was discussed

Investigation of the relationship between flexural modulus of elasticity and functionally graded porous structures manufactured by AM

There is an increased interest to produce open porous metallic lattice structures with regular unit cell architectures by additive manufacturing processes, which were impossible or difficult to manufacture using conventional techniques. In this study, the physical and mechanical properties of functionally graded porous structures were investigated to establish a relationship between porosity and elastic modulus of the cellular structure. Three different unit cell structures of diamond, cubic, and octahedroid and three different strut thicknesses of 0.3 mm, 0.5 mm, and 0.7 mm were designed for the experimental and theoretical study. A functionally graded porous structure was formed by using three different unit cell sizes (1.8 mm, 2 mm, and 2.2 mm) in each model. The specimens were produced by laser powder bed fusion (L-PBF) using Ti‐6Al‐4V powder and subjected to a three-point bending test after heat treatment. A mathematical model was created to determine the modulus of elasticity of the porous structures. Experimental results were compared with the theoretical calculations. As a result of this study, a correlation was established between the flexural modulus of elasticity and the porosity of the three different cell structures.Türkiye Bilimsel ve Teknolojik Araştırma Kurumu (TÜBİTAK), MAG-116R02

Additive manufacturing design approach to strut-based functionally graded porous structures for personalized implants

This study aims to create mathematical models (MMs) and maps that will facilitate personalized implant design and provide the selection of design parameters that give desired mechanical and physical properties. For this purpose, strut-based functionally graded porous structures (FGPSs) were designed using three different unit cell structures, unit cell sizes, and strut thicknesses. A total of nine specimens were produced by L-PBF using Ti-6Al-4V. The porosities were measured by dry weighing and Archimedes methods. In addition, three MMs were derived that give the effective porosity of the specimens based on the unit cell structures. A relationship was established between the modulus of elasticity obtained from the compression test and the design parameters. MMs that give the elastic modulus and porosity of FGPSs depending on unit cell size and strut thickness have been derived. By using these models, maps giving the mechanical and physical properties of the functionally graded porous structures were generated. Thanks to these models and maps, personalized implant design will be facilitated, and biocompatibility will be increased. Thus, undesired problems such as early revision and repetitive surgeries will be minimized and the quality of life of the patients will be increased.TÜBİTAK - MAG-116R02

Effect of Nanoparticles on Carbon Fiber/Epoxy Nanocomposite Laminates Fiber, Matris and Void Volume Fraction

Bu çalışmada farklı oranlardaki nanopartikül takviyesinin fiber, matris ve boşluk hacim oranlarına etkisi incelenmiştir. Karbon fiber/epoksi nanokompozit plakalar vakum infüzyon yöntemi (VİY) ile üretilmiştir. Üretim öncesinde matris elemanı olan epoksi içerisine farklı oranlarda nanopartikül katılmıştır. Üretilen nanokompozitler standartlarda verilen ölçülerde hazırlandıktan sonra yakma testine tabi tutulmuştur. Nanopartikül katkısı arttıkça hem epoksinin viskozitesi hem de epoksi içerisinde nanopartikül kümelenmeleri artmıştır. Bunun sonucunda üretim esnasında epoksinin basınç altında vakumlanması ve fiberleri ıslatması zorlaşmıştır. Yakma testi sonucunda %5 nanopartikül katkısının boşluk hacim oranını %221 arttırdığı sonucuna ulaşılmıştır

Investigation of tensile properties of glass fiber/ nanocomposites laminates enhanced with graphene nanoparticles

In this study, mechanical properties of graphene nanoparticles (GNP) added glass fiber/epoxy nanocomposite specimens and the effect of GNP were investigated by applying the tensile test. Specimens were produced by vacuum assisted resin transfer molding (VARTM) method on the CNC device in standard sizes. The results obtained from the tensile test of the specimens prepared with the addition of GNP at the rates of 0.15%; 0.25%; 0.35%; 0.45% and 0.75% were compared with the sample without GNP. According to the test results, the tensile strength increases with the increase in the rate of GNP. The highest tensile strength was found when the GNP rate was 0.45%. At this rate, the tensile strength increases by 31.29% compared to the specimens without additives. However, increasing the rate of GNP more than 0.45% affects the mechanical properties negatively and causes a decrease in tensile strength. Finally, finite element analysis (FEA) was made by designing the produced specimens. FEA results were compared and found to be compatible with the experimental results