Materials Engineering - Materiálové inžinierstvo (MEMI - E-Journal)
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Fretting–fatigue behavior of bolted joints using FEM method
Get PDFIn this paper, the fretting damage of a mechanical bolted assembly in three dimensions is studied using a numerical approach. The study consist to analyze the cylindrical coordinates in stress fields and other fretting parameters depending on the angle and radius of the contact areas, and also to determine the position of the initiation and propagation of the crack.The numerical simulation is done in 3D in order to better describe the real behavior in fretting of a bolted joint. According to the simulation results, the tightening torque plays a significant role in the load transfer. The results allowed us to determine the stress that triggers the initiation and crack propagation, and locate the damaged area by fretting
Welding of the tube girder cover made of the C-Mn high strength steel
No full textThe welding procedure and technology for welding the cover of the tube girder is presented in this paper. The tube cover is made of the C-Mn high-strength steel. The welding has to be performed over the whole perimeter in the V groove. Since the structure in question is a very responsible one (a part of the assembly of the large hadron collider – LHC), the check of the base metal chemical composition and the mechanical properties had to be conducted before actual prescribing of the welding process type and the complete welding technology. Then the weldability of the base metal was estimated, which showed that this particular steel was conditionally weldable with application of preheating. The welding technology was prescribed, based on the previously determined parameters including the welding procedure and the filler metals selection. The prescribed technology was afterwards executed on the selected experimental samples. To verify that the selected technology was adequate, the hardness and the microstructure of all the zones of the welded joints were determined. Analysis of executed experimental welds on chosen samples has confirmed that the welding technology was appropriate and that it could be applied to the real part – the LHC assembly
On the recrystallization and texture of Fe-36%Ni alloy after accumulative roll bonding and annealing at 600 °C
Get PDFMicrostructure and texture evolution of Fe-36%Ni (wt.%) alloy after 1, 5 and 10 accumulative roll-bonding (ARB) cycles and annealing at 600 °C up to 3600 seconds were studied using electron backscatter diffraction. Microstructural and textural changes after ARB and annealing were compared to those existing in the literature after conventional rolling. The microstructure was not stable at 600 °C for all ARB samples even after 3600 seconds of annealing. The recrystallization texture was dominated by the Cube {001} texture component. Recrystallization kinetics were determined using microhardness measurement and were close to those after cold rolling with Avrami time exponent around unity. The texture evolution at high strain was discussed in terms of grain boundary migration obstruction by the formation of layer interfaces and small recrystallized grains near the bonded interfaces
ZnO THIN FILMS PREPARED BY ATOMIC LAYER DEPOSITION
Get PDFThe purpose of this paper is present the influence of deposition conditions of nanometric zinc oxide thin films using atomic layer deposition on the mechanical and optical properties. The influence of the deposition temperature and the number of cycles on the transparency and adhesion of the ZnO, thin films was investigated. In addition, the results of chemical and phase composition analysis of the layers and their topography and structure were discussed. As a substrate for the investigated thin films was used glass. For the preparation of ZnO thin films was used ALD method. Selecting this method is justified by the high quality and good properties of the deposited layers
EFFECTS OF CHEMICAL COMPOSITION ON MECHANICAL PROPERTIES OF Al-Mg-Si-Mn BASED ALLOYS
Get PDFEffects of chemical composition and heat treatment on the microstructural and mechanical properties of cast Al-Mg-Si-Mn alloys were investigated. The as-cast and heat treated alloys were investigated by microhardness, macrohardness and tensile stress measurements, scanning and transmission electron microscopy, energy dispersive X-ray analysis and differential scanning calorimetry. It was observed that the mechanical properties depend strongly on composition and addition of excess elements and eutectic phase. Heat treatment leads to the enhancement of all mechanical properties of alloys, which are the result of several mechanisms
EVALUATION OF WEAR BEHAVIOR OF Al-Si ALLOY USING SiC AS THE REINFORCEMENT
Get PDFThe current study investigates the wear behavior of the SiC particles reinforced Al-Si alloy composites developed using the stir casting process. The results were obtained from the wear tests of the cast Al-Si alloy and prepared SiC reinforcement composites containing 3 % wt and 9 % wt using fine and coarse size SiC particles. The wear test of all the developed composites were done at different testing conditions with varying loads. The analysis of wear traces, as well as the wear debris, was done at every composition but at higher loads. It was observed that the wear resistance was improved with increasing the amount as well as decreasing the size of the SiC particles. However, the wear rate of the composites increases with increasing the applied load. From the microstructural study of specimen after the wear test one can conclude that both adhesive and abrasive wear mechanisms contribute for wear of SiC particle composites
Mechanical Properties of Stellite-6 coated AISI 316L Stainless Steel
Get PDFPresent paper describes the mechanical properties of Stellite-6 coated AISI 316 L stainless steel. Specimens were coated using Detonation Gun thermal spray process, with different coating thicknesses of Stellite-6 ranging from 50 µm to 150 µm. Afterwards their properties like tensile strength, impact strength and micro hardness were evaluated on the basis of the results obtained from the experimentation. For comparison of substrate and coated material the graphs were plotted. The coated specimens exhibited superior impact strength and microhardness than that of the bare specimens, whereas the tensile strength of coated specimens decreased marginally with the increase in coating thickness
Wear resistance of layers hard faced by the high-alloyed filler metal
Get PDFThe objective of this work was to determine the wear resistance of layers hard faced by the high-alloyed filler metal, with or without the austenite inter-layer, on parts that operate at different sliding speeds in conditions without lubrication. The samples were hard faced with the filler metal E 10-UM-60-C with high content of C, Cr and W. Used filler metal belongs into group of alloys aimed for reparatory hard facing of parts damaged by abrasive and erosive wear and it is characterized by high hardness and wear resistance. In experiments, the sliding speed and the normal loading were varied and the wear scar was monitored, based on which the volume of the worn material was calculated analytically. The contact duration time was monitored over the sliding path of 300 mm. The most intensive wear was established for the loading force of 100 N and the sliding speed of 1 m.s-1, though the significant wear was also noticed in conditions of the small loading and speed of 0.25 m.s-1, which was even greater that at larger speeds.
Effect of tool shape and welding parameters on mechanical properties and microstructure of dissimilar friction stir welded aluminium alloys
Get PDFIn the present experimental study, dissimilar aluminum alloy AA5083 and AA6082 were friction stir welded by varying tool shape, welding speed and rotary speed of the tool in order to investigate the effect of varying tool shape and welding parameters on the mechanical properties as well as microstructure. The friction stir welding (FSW) process parameters have great influence on heat input per unit length of weld. The outcomes of experimental study prove that mechanical properties increases with decreasing welding speed. Furthermore mechanical properties were also found to improve as the rotary speed increases and the same phenomenon was found to happen while using straight cylindrical threaded pin profile tool. The microstructure of the dissimilar joints revealed that at low welding speeds, the improved material mixing was observed. The similar phenomenon was found to happen at higher rotational speeds using straight cylindrical threaded tool.
The contact and compacting pressures influences on the quality of the friction welded joint
Get PDFThe theoretical and experimental analyses of the friction welding pressure influence on the plastic deformation level and the quality of the friction welded joint are presented in this paper. The joint of the tempering and the High-Speed steel was realized by the friction welding. The objective was to relate the two basic process parameters - the friction and compacting pressures - to plastic deformation parameters during the friction welding of two the steels. The fact that materials are dissimilar additionally complicates the welding procedure and its analysis. The friction welding is a specific and complex process, since in the joint zone material is heated and plasticized with necessary action of the multi-step pressure to realize the joint. The total deformations in the axial and radial directions are directly dependent on the applied welding pressure. Considering that geometry and shape of the friction welded joint directly depend on the friction pressure, some welded joints' basic shapes obtained with various pressures are presented. The experimental investigation was conducted on cylindrical samples made of the two steels and the analysis of results served for establishing the influences of the friction and compacting pressures on changes of the steel samples dimensions and shapes.