Cenk Misirli

Characterization of Properties in Friction Welded Stainless Steel and Copper Materials

The aim of this study is to investigate the metallurgical and mechanical properties of friction welded stainless steel-copper joints. One of the manufacturing methods used to produce parts made from different materials is the friction welding method. Application of classical welding techniques to such materials is difficult because of they have different thermal properties. Stainless steel-copper joints are inevitable for certain applications due to unique performances such as higher electric conductivity, heat conductivity, corrosion resistance, and mechanical properties. In the present study, austenitic stainless steel and copper parts were joined by friction welding. Tensile, fatigue, and notch-impact tests were applied to friction welded specimens, and the results were compared with those for the original materials. Microstructure, energy dispersive x-ray, and x-ray diffraction (XRD) analysis and hardness variations were conducted on the joints. Results showed that various intermetallic phases such as FeCu4 and Cu2NiZn occurred at the interface. It was found from the microstructure and XRD analysis that intermetallic phases formed in the interface which further caused a decrease in the strength of the joints. However, hardness of the copper increased slightly, whereas the hardness of steel decreases slightly on the horizontal distance from the center.

On materials flow using different lubricants in upsetting process

Purpose – The purpose of this paper is to apply the upsetting process to cylindrical specimens using flat end dies in which three types of lubricants were used. In many industrial processes, friction and lubrication have major advantages and are key during the metal forming process. Upset forging is a process which increases the diameter of the work-piece by compressing its length. Design/methodology/approach – The materials flow for various materials using different lubricants in upsetting was investigated in this study. AISI 304 austenitic-stainless steel and commercially pure aluminium (Al99.7) were used as the test materials. The upsetting process was applied to the cylindrical specimens using flat end dies. Three types of lubricants, namely, grease, graphite and SAE 40 oil, were used in this study. Experiments were performed using a hydraulic press, which has 5 mm/s ram speed, with a capacity of 150 metric tons. On the other hand, finite element methods (FEMs) have been carried out to analyse the for...

Mechanical and Metalurgical Properties of Friction Welded Aluminium Joints

Aluminium alloys are alloys in which aluminium (Al) is the predominant metal. The typical alloying elements are copper, magnesium, manganese, silicon and zinc. There are two prin‐ cipal classifications, namely casting alloys and wrought alloys, both of which are further subdivided into the categories heat-treatable and non-heat-treatable. About 85% of alumini‐ um is used for wrought products, for example rolled plate, foils and extrusions. Cast alumi‐ nium alloys yield cost effective products due to the low melting point, although they generally have lower tensile strengths than wrought alloys. The most important cast alumi‐ nium alloy system is Al-Si, where the high levels of silicon (4.0% to 13%) contribute to give good casting characteristics. Aluminium alloys are widely used in engineering structures and components where light weight or corrosion resistance is required [1].

The Effects of Square and Circular Die-Orifices on the Performance of Combined Extrusion-Forging Process

The upper bound (UBM) and finite element methods (FEM) both coupled with experiments have been conducted to analyze forming performance, load prediction, and pressure analyses in a combined extrusion-forging process using square and circular die orifices. The forming load was predicted by the UBM and the pressure distribution was analyzed by FEM and the performance of both the methods was compared to each other. The required extrusion forging force for square die orifice was found to be higher than in the circular die orifice. The highest pressures occurred on the edges of the square and circular orifices and the pressures increased with increasing friction and deformation. Although extrusion force predictions were found to be slightly higher in UBM than FEM, they were in good agreement with experimental results. The present analyses showed that UBM can be used in rapid prediction of required extrusion-forging loads and material flow, and FEM is more suitable to use in pressure distribution analysis for production of square and cylindrical parts.

Properties of Cold Pressure Welded Aluminium and Copper Sheets

Cold pressure welding has been used as an industrial process with an increasing rate for several years. In this study, cold pressure welding has been applied to aluminum and copper alloy sheets having commercial purity. Hydraulic press having 150 metric-ton capacities has been used for welding process. As the surface roughness and the weld deformation ratios of aluminum sheets increased, tensile strength of the joints also increased. Purchased specimens with original roughness had the lowest weld deformation as-is and it was not possible to join these sheets at 30% weld deformations. Hardness increases due to local hardening at the interface as a result of cold deformation. Results showed that the cold pressure welding technique in lap form resulted in strong Al-Al joints and the intermetallic layer formed in Al-Cu joints did not affect the joint strength to a great extent.

Properties of Al/SiC metal matrix composites

Abstract Metal matrix composites have higher resistance compared to ceramic and polymer matrix composites. In this study, an aluminum 5754 alloy was fortified using 10 % SiC to obtain a metal matrix composite with properties superior to the original alloy. An improvement of mechanical properties was obtained by reinforcement with aluminum matrix composites which can be produced with various techniques. Mechanical properties of the composite material (Al/SiCp) were initially investigated, and then, the metallurgical properties were determined using an optical metal microscope and SEM. Furthermore, the percent of elongation, tensile strength and Vickers hardness are the input parameters for the mechanical properties. The tensile strength as an output response parameter of Al/SiCp materials was analyzed using experimental Taguchi technique design as an orthogonal array. In the present investigation, experiments were carried out to compare experimental results with predicted optimal values. ANOVA analysis revealed that the percent elongation-PE (%) was the input parameter having the highest statistical influence on tensile strength. It could be shown that the composite material was resistant against both static and dynamic loads. It was also shown that silicon carbide mixed homogenously with aluminum.

Characteristic properties of AlTiN and TiN coated HSS materials

Purpose – The purpose of this paper is to examine mechanical and metallurgical properties of AlTiN- and TiN-coates high-speed steel (HSS) materials in detail. Design/methodology/approach – In this study, HSS steel parts have been processed through machining and have been coated with AlTiN and TiN on physical vapour deposition workbench at approximately 6,500°C for 4 hours. Tensile strength, fatigue strength, hardness tests for AlTiN- and TiN-coated HSS samples have been performed; moreover, energy dispersive X-ray spectroscopy and X-ray diffraction analysis and microstructure analysis have been made by scanning electron microscopy. The obtained results have been compared with uncoated HSS components. Findings – It was found that tensile strength of TiAlN- and TiN-coated HSS parts is higher than that of uncoated HSS parts. Highest tensile strength has been obtained from TiN-coated HSS parts. Number of cycles for failure of TiAlN- and TiN-coated HSS parts is higher than that for HSS parts. Particularly TiN-...

An Investigation on Plastic Matrix Composite Materials

Composite materials with plastic matrix consist of a fiber material, which is used as the core and a matrix material, which forms the volumetric majority around that fiber material. Glass fiber reinforced plastics (GRP) are polymer-based plastic matrix composites that are used in a wide range of applications. In this work, a plastic-based composite material, which is used in tractor bonnets, was produced and thermal analysis and scanning electron microscopy (SEM) analysis of fracture surfaces for this material were performed. The SEM images of the fractured surfaces of the composites showed varied extents of fiber pull-outs under tensile failure modes. The nature of interfacial adhesion was discussed on the basis of the SEM study. A good correlation was established between the SEM study and the mechanical strength properties of the composites. However, it was observed that vinyl ester resin is a more suitable matrix for tractor bonnet parts due to its higher thermal resistance compared with orthophthalic resin. Keywords: composites, thermal analysis, scanning electron microscopy

Mechanical and metallurgical properties of AlTiN-coated HSS materials

Purpose – The purpose of this paper is to examine mechanical and metallurgical properties of AlTiN coating HSS materials in detail. Design/methodology/approach – In this study, high-speed steel (HSS) parts were processed by the way of machining and were coated with AlTiN on physical vapour deposition (PVD) workbench at approximately 650°C for 4 h. Tensile strength, fatigue strength and hardness tests for AlTiN coated HSS samples were performed. Samples were also analyzed by energy dispersive X-ray analysis (EDS), X-ray diffraction (XRD) and scanning electron microscope (SEM). The results were compared with uncoated HSS components. Findings – It was found that an amorphous aluminium-oxide layer emerges on surface of parts by AlTiN coating. This layer prevents further oxide formations. The coating thickness of AlTiN-coated sample is between 1,530 and 1,558 μm. Compared to uncoated HSS, AlTiN coated HSS gives higher performance. Research limitations/implications – It would be interesting to search different ...