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Fatigue failure is a process resulting first from change of mechanical properties, then fatigue crack initiation occurs and progressive growth of crack (propagation of fatigue crack) leading to final fracture. The failure can occur either in low number of cycles (≤ 104 cycles; low cycle fatigue) or over millions of cycles (high cycle fatigue). The fatigue behavior of AISI 316L austenitic stainless steel on microstructure was investigated. The fatigue fracture was investigated after three point cyclic bending test which was realized on V-notched testing bar. Fatigue crack nucleated from several sites under the notch. The failure mechanism proceeded afterwards by repeated episodes of fatigue striations as examined under scanning electron microscope. Before the fracture surface observation the surface hardness was measured under the originated crack where the area of plastic deformation can be found. In this area the hardness values raised approximately to 379 HV due to plastic deformation strengthening. With the increasing distance from the crack the hardness values decreased approximately to 246 HV.

The present article describes the effect of adding iron into melt, and its impact on the microstructure, chemical composition and mechanical properties of AlSi7Mg0.3 alloy. Higher iron content is typical of the so-called secondary alloy, which becomes increasingly used by a growing number of manufacturers in the production process of high-quality castings. The behaviour of AlSi7Mg0.3 alloy with high Fe content has not been scientifically investigated and sufficiently described, therefore working with secondary alloy is very problematic when focusing on high-sophistication castings for the automotive industry. In general, iron is unwanted in aluminium alloys, and its content should be kept as low as possible. The only exception is the process of pressure die casting where we can tolerate iron content up to 1 wt. %. In gravity casting of Al-Si-based alloys, the critical iron content changes mainly depending on the silicon content. The experimental part of this article investigates the impact of gradual addition of iron into AlSi7Mg0.3 alloy on the content of the main alloying elements such as, in particular, Si and Mg. In order to eliminate the negative effect of iron in the alloy, we used in the experiment the correctors Ni and Cr in the form of AlNi20 and AlCr20 master alloys.

There are a large number of special methods for exploring the internal condition of materials on the basis of eddy currents. A major use of this method can be seen in surface engineering, particularly in studying some state quantities of surface integrity. It is also an irreplaceable tool in surface engineering. The reason is that no other affordable method provides information on both the surface and the sub-surface regions, as the latter are difficult to reach by most other inspection methods. It must be noted that the sub-surface region is significant, and dictates, to a large extent, the behaviour of the overlying surface. This article explores a non-traditional application of eddy current inspection. This inspection technique is typically used for detecting discontinuities in material. The study presented here involves a use of this non-destructive testing method for studying work hardening in two metallic materials: EN AW-1090 aluminium alloy, and S235JR-C carbon steel.

The objective of this work is to assess cutting speed during the wire electrical discharge machining (WEDM) depending on the machine parameters setting (gap voltage, pulse on time, pulse off time, wire speed and discharge current) and follow-up assessment of the surface quality achieved. In order to achieve efficient machining the maximum cutting speed is required, however maintaining of the required quality and functional characteristics of the machined surface must be considered. Surface morphology during the wire electrical discharge machining is formed by a high number of craters, of which depth has direct effect on area parameters and profile parameters of the surface quality. These parameters were evaluated using Contactless 3D profile-meter based on the principle of coherence correlation inter-ferometry IFM G4 from the Alicona producer.

The possibilities for reparation by hard facing of the damaged working parts - the hammers of the secondary stones crusher are investigated in this paper. The analyzed crusher is stationary and it belongs into a group of the process equipment aimed for producing the crushed stone. The produced stone is later used for manufacturing various construction materials like asphalt, concrete, etc. Wear of the crusher's working parts occurs during the exploitation due to operation with very hard materials. That wear is usually abrasive and of high intensity what causes failure of the working parts and consequently the machine's downtimes and appearance of various types of losses, primarily financial ones. To prevent that, and to reduce the downtimes as well, one uses reparation technologies, one of which is hard facing. The analysis of the mass losses of the hard faced parts, after certain number of hours of the crusher's field operation, is performed in this paper.

Sandwich composites are well known for many years and its place among the construction materials have they deserved mainly due to very good mechanical properties related to their weight. These materials have been a subject for many researches, but very few of them were focused on the behavior of curved constructions in bend with respect to their specific shape (curvature). With increasing number of new materials and resulting possible material combinations, it is necessary to characterize performance of new prepared structures and also evaluate the effect of a shape on the behavior of sandwich constructions with regard to their material composition. Presented paper deals with an investigation of flat and curved beams of sandwich structures, which correspond by their material composition to those, used in transport industry. Specifically, the influence of curvature size on a change of bending properties of structures with specific material composition compared to flat constructions is evaluated. This influence is also investigated in terms of specimen clamping and type of bending test. Obtained results showed that properties of sandwich structures are dependent not only on size of curvature, bud also on core thickness. Moreover, these results can help designers, constructers or technologists with design, dimensioning or production of these materials for specific applications.

Microscopy is mainly used in tribotechnical diagnostics for the analysis of the total number and morphology of the wear particles in the lubrication systems. Wear particles may accelerate wear and ultimately may cause a failure in lubricating systems. Therefore, this paper deals the tribodiagnostic problem which is focused on microscopic analysis of wear particles and additional tribodiagnostic analysis of motor oil. There was taken sample of motor oil after failure of turbocharger of combustion engine. The purpose of the paper is to compare the results of microscopic analysis for evaluation of wear particles in motor oil. These analyses are key for assessing wear of the combustion engine and for indicating of impending failure. The aim of this experiment was to assess hypothesis that scanning electron microscopy (SEM) is appropriate for tribology diagnostics of seized turbocharger of internal combustion engine.

In this work there are published results about fatigue resistance of ductile iron with various types of matrix obtained at cyclic loading in very-high-cycle region. The results show continuous decrease of the stress amplitude with increasing of cycles number to the failure. The tensile strength increase is not accompanied with corresponding increase of fatigue properties. The fatigue durability decreases while the tensile strength increases.

Microscopy is nowadays applied in different research disciplines. It is widely used in the field of tribology and its application to technical systems. Microscopy is able to analyze morphology of wear particles generated in various technical systems of vehicles. Wear particles are formed not only in lubricating systems, but also in fuel systems. Number of wear particles and their morphology consequently accelerate the process and the intensity of wear. Quite frequently mentioned problem is impact of biofuels or other fluids on their technical condition. Newly produced biofuels may lead to increased wear of the fuel injection system due to reduced lubrication capability compared to conventional fuel. Their presence in fuel systems may accelerate wear and eventually may cause failure. Article describes laboratory experiments focused on influence of various fuels on functional surfaces of fuel injection system parts from the perspective of scanning electron microscopy. The aim of the experiment was to prove or disapprove hypothesis that there is significant impact of biobutanol on creation of wear particles of fuel injection system. The results showed that biobutanol has a lower lubricating ability to form sufficient layer in order to prevent increased wear.

Detection system of infrared thermography technology was designed, taking a non-refrigeration focal plane infrared camera and the pulse flash heating system with high energy as the core. Combining with the performance parameters and structure features of the hardware equipment, integrated control system was designed. Meantime, the cover and reflector for the detection system were fabricated, which improved the uniformity and the utilization rate of energy for the thermal excitation source of the flash lamp. Based on the Delphi program, control, acquisition, processing and analysis system for the infrared image sequence were developed. And defect identification software was also researched which could implement the quantitative calculation and analysis for the parameters of defect size, location, perimeter, area and depth. Finally, experiments for metal and composite with flat bottom defects were carried out by the use of the detection system proposed in this study. The results show that the detection system has the advantages of well controllable performance, convenient operation, perfect detection effect, powerful image processing functions, which can meet the testing demand for engineering application.

This work investigates issues of BTA drilling of deep holes with slenderness ratio L: D = 45/60 of high strength steels with a tensile strength of Rm = 1350/1600 MPa. Methodology for testing of surface when turning and boring deep holes after drilling accordingly, heat treatment, straightening annealing and stress relief, was based on the statistical monitoring of eccentricity surface deviation from the theoretical axis of the bore axis for instruments with changeable carbide cutting inserts with CVD/PVD coatings under operating conditions with the number of 30 pieces. Measurement results of eccentricity of surfaces for locating strips before and after machining (as in turning and drilling for more cuts) are statistically processed in tables and graphs, as well as the obtained and acquired results. Article presents the optimized parameters of BTA drilling. Originally used tools for drilling were upgraded by using carbide inserts of type 14.171.55-00/0400 or /0250 by Krupp WIDIA. Influences of factors are discussed, and the monitoring of factors that produce holes of desired eccentricity is presented.

Based on the value of longitudinal distribution of the residual stresses in the strip with the cold rolled strip in different forms under stress loading, this paper establishes a finite element model. According to the simulation analysis on different stress curve functions and under some coefficient combining conditions of different stress curve functions, it is discovered that the stress acting lengths and the features are completely different under the actions of even-degree and odd-degree stress functions, and under the even-degree function, the residual stresses are distributed evenly at the far end of the strip, and the length location of the point where the residual stresses tends to be stable on the strip are linearly related to the strip width; under the odd-degree function, the residual stresses are distributed linearly in the horizontal direction of the strip while without any changes along the strip length. According to the analysis results of the strip's shear stress, a little strip shear stress is not enough to produce deformation. The result of this paper has profound guiding significance for cold-rolled strip flatness closed-loop control. Only with different control strategies for different flatness deviations after fitting, can the quality of the strip steel flatness be improved more effectively, thereby reducing the impact of the lag in flatness detection on the strip flatness control as far as possible.

The development of economy can not be separated from sufficient energy supply. With the progress of technology, the distribution network gradually expands the capacity and transportation, but also brings security risks. The distribution automation system can effectively manage the power grid faults. This paper briefly introduced the calculation model of the economic cost and the reliability rate of the distribution automation, and then the assembly scheme of the distribution terminal was optimized by using the improved binary particle swarm optimization (PSO) algorithm. Next, the simulation analysis of the distribution terminal distribution on a 10KV main feeder line in Xuanwu District of Nanjing city was carried out in MATLAB software. The results showed that the improved binary PSO algorithm could optimize the assembly scheme of remote metering and remote signalling and the assembly scheme of remote metering, remote signalling and remote control rapidly; the hybrid assembly scheme needed a little more time; the power supply reliability rate of the optimized three terminal assembly schemes was over 99%; the hybrid assembly scheme had higher power supply reliability rate and the lowest economic cost.

The paper presents the results of the surface morphology of aluminium alloys after milling. The 3D surface roughness parameters Ra, Rz, RSm were examined. Functional relationships between the cutting forces, the torque and the roughness parameters were established. The investigation was carried out with respect to functional characteristics of the surface of aluminium alloys. Two different aluminium alloys: 2024 and 6082, were investigated. Two different milling strategies were employed: milling with a trochoidal tool path and milling with a conventional tool path. Different radial depths of cut were applied in the tests. The percentage of the radial depth of cut was increased every 5 %, from 5 % to 40 %. The results were compared with the conventional machining.

In this work the influence of selected elements (Sn, Pb, Bi and Sb) on microstructure and mechanical properties of commercial AlSi8Cu2 alloy at four different temperatures (20, 100, 200, 300 and 350 ° C) was studied. The influence of individual elements and their combinations was studied. The content of elements in the range of 0.1-1 wt% was studied. Significant influence of these elements was found from 0.5% content especially at elevated temperatures.

Thanks to their chemical and physical properties, the cutting fluids can significantly affect the process of machining - the use of cutting fluid reduces the roughness of the machined surface and increases the tool life. However, during the machining the oil from the hydraulic system of the machine often gets into the cutting fluid, which can alter the properties of the cutting fluid. In scientific literature there is no information on the effect of the hydraulic oil entering the cutting fluid on the tool life and roughness in machining of the structural steel. In this regard, at the laboratory of the Department of Machining and Assembly of the Technical University of Liberec, there has been conducted a study to ascertain the effects of hydraulic oil getting into different types of cutting fluids during the milling of structural steel.

Determining transformation temperatures of novel steels is an important step towards finding parameters for their heat treatment. In advanced high-strength steels for Q&P processing (Quenching and Partitioning), the crucial processing characteristics are the temperatures of the start and end of austenitization and the Ms temperature. Q&P processing is characterized by quenching from a full-austenitization temperature to below the Ms, and subsequent holding at the partitioning temperature. This leads to martensitic microstructures with retained austenite between martensite needles and to ultimate strengths above 2000 MPa and elongation levels up to 10%. Several AHS steels containing 0.4% C were manufactured and cast for this experiment. Their main alloying additions were manganese, silicon, chromium, molybdenum and nickel. Their transformation temperatures were first calculated using the JMatPro software. The values were validated by dilatometry measurements. Based on these results, a Q&P process route was designed and put to test. The resulting microstructures were documented using optical and scanning electron microscopy. Strengths of more than 2300 MPa and up to 11% elongation levels were obtained.

An article deals with the assessment of the heat treatment of the material for a particular machine component. This material is 34CrNiMo6, made of two melts. This steel belongs to a group of materials with special properties for working at higher temperatures and for the production of demanding components, turbine wheels, cardan shafts, toothed wheels. The material was evaluated for microstructure quality before and after heat treatment. Based on metallographic microstructures, it is possible to review the heat treatment mode, which subsequently affects the mechanical properties of the components. For a particular design element, better cast material was recommended based on a comprehensive evaluation.

The Central Solenoid Model Coil is a hybrid superconducting coil being developed in Institute of Plasma Physics Chinese Academy of Sciences. The R&D of Central Solenoid Model Coil will lay the foundation for the fabrication of China Fusion Engineering Test Reactor Central Solenoid coil. One of the main purposes during the R&D of Central Solenoid Model Coil is to verify its mechanical performance under the complicated load cases. In order to efficiently and accurately carry out the mechanical analysis, some necessary parameters such as the electromagnetic state under assembly error, the thermal contact resistance and the equivalent material property of conductor winding packet should be calculated in advance. The electromagnetic state here mainly refers to the asymmetric magnetic field and electromagnetic force. The calculation of magnetic density is based on elliptical integrals, the results will provide guidance for the assembly optimization of coil modules. And the subsequently obtained electromagnetic force will offer load boundary condition for the coil stability analysis. The thermal contact resistance is calculated under the assumption that the interface asperity approximately obeys the Gaussian distribution. The thermal contact resistance will be used in the thermal analysis. And the key advantage is which makes the prediction of preload force variation more accurate during coil the cooling down process. The equivalent material property is calculated by using generalized Hook's law and finite element method. Based on the equivalent material property, the coupling analysis model of CSMC will be significantly simplified. Moreover, it makes CSMC full model analysis under non-uniform loads become possible.

This paper reports on the influence of production parameters on the properties of 3D printed magnesium alloy Mg-4Y-3RE-Zr (WE43) produced by the selective laser melting method. We present microstructures and mechanical properties of four selected samples prepared under various production parameters. Optical and scanning electron microscopy together with energy-dispersive X-ray spectrometry were used for microstructure analysis. Porosity was evaluated based on image analysis. To represent differences in mechanical properties, microhardness measurement and compression tests were performed. Based on our observations of microstructure quality and performed tests, the results of the parameter impact study are further applied to the production of products of the required quality.

The paper deals with a method and technology for increasing of precision sorting of transparent materials - glass. The recycled glass is a valuable material which is necessary as an ingredient in the process of glass manufacturing. We propose a very fast industrial device based on FPGA (field-programmable gate array) image processing along with a novel algorithm for a robust real-time treatment of acquired data. The system consists from a line-scan camera with fast CameraLink interface, FPGA processing, battery of valves propelled via pneumatics and nozzle block. Very important part of the system is a background configuration software enables precise assessment of required limits as inputs to FPGA processing. The overall performance is discussed from the perspective of laboratory and industrial tests. The proposed FPGA image processing can be utilized for further future enhancements in the field of precise sorting of glass with stuck labels on it. The results give very good performance even in the industrial environment with a lot of dust and dirt and hence the glass does not need to be extensively cleaned.

This contribution is divided into two sections. The first one deals with identifying the cause of fracture in a ring, which fractured after weld surfacing. Optical and scanning electron microscopy and hardness testing were employed. Chemical composition was determined using the GDOES and EDX methods. Although weld surfacing has led to fracture in the base material, the actual problem was in the inadequate microstructure of the base material. Microscopic analysis revealed that it was heterogeneous. It contained distinctive segregation bands with bands of complex carbides and pearlite colonies, which are undesirable. The microstructure of this steel should be fully austenitic. In order to remove the heterogeneities, solution annealing was proposed and carried out successfully. The second section of this paper explores the options for revealing the microstructure of Hadfield steel. Etching reagents from the literature and authors' experience were put to test.

This paper demonstrates the new multi criterion decision making (MCDM) techniques were used, i.e. the weighted aggregated sum and product assessment (WASPAS) technique. This involves the modified air abrasive jet machining (MAAJM) of Nickel 233 alloy using carbide coated nozzle in 3mm dia with three responses are considered as against the process variables of injecting pressure, standoff distance, and abrasive mesh size. The optimal combination of MAAJM process parameter for simultaneous minimization of taper angle, surface roughness and maximization of MRR are injecting pressure of 0.686MPa, standoff distance 9mm and abrasive mesh size 400μm with 3 diameter carbide coated nozzle. The optimal results attained with the WASPAS technique demonstrated to good relation with another technique multi objective optimization rational analysis (MOORA).

The given paper is closely connected with the experimental and numerical modal analysis of the carbon composite plate damaged by cut. In relation to the tested carbon composite, modal analysis was performed by help of special measuring device Pulse 12. The mentioned device was supplied by company Brüel & Kjear and the experimental measurements were carried out using damaged and undamaged plate sample which were prepared from the mentioned material hereinbefore. The investigated and analyzed plates of carbon composite were made of six layers of carbon fibres and they were arranged under the angle 90º (it is like fabric material made off carbon fibres). The layers arranged in the given way were joined by epoxide resin MGS 285. The experimental measurement of eigenfrequencies of carbon composite plates was carried out using the undamaged and damaged sample with proportions 78 mm x 78 mm while ten measurements were performed for each one specified site of the sample. In relation to the damaged plate sample, there was cut in length of 20 mm in the centre border. The finite element method in the software system ADINA v.8.6.2 was used for numerical analysis of the eigenfrequencies.

This work deals with the construction design and manufacturing of a cylinder liner which is used in a Jawa 50 motorcycle in order to increase the performance characteristics. The liner is pressed in the aluminium cylinder case with ribs so together it makes a two-stroke motorcycle cylinder. The first step was to build an analysis of the technical design of the original motorcycle cylinder to detect any restrictive parameters for the modifications, especially of the cylinder liner, so the motorcycle can be used for racing. As well as the construction design of the liner, the work deals with the clamping and manufacturing of this part too. The CNC code was written using SolidCAM software. Then the liner was manufactured in a turning-milling centre. The purpose of this work is to produce a liner so that it forms a racing motorcycle cylinder together with the aluminium case with the ribs. The basis of this project is the correctness of the construction design and the accuracy in manufacturing so that the engine can achieve the demanded parameters with respect to usability, engine cooling, gear setup, engine life and the other restrictive parameters.

Additive manufacturing (AM) has shown promise to process parts for end-use applications, however stringent requirements must be fulfilled in terms of reliability and predictability. The expensiveness of raw materials for AM, especially for metal-based Powder Bed Fusion (PBF), brings about the need for a careful recycling of powder, but the effect of powder reuse on both processing conditions and final part performance is still the focus of intensive research in the open literature. Although ASTM F2924-14 specifies the virgin-to-used powder ratio to be introduced to manufacture titanium-6aluminum-4vanadium (Ti-6Al-4V) components by PBF, a deeper understanding of the effect of powder recycling on the mechanical properties of finished parts is expected to foster a more efficient and safe reuse. The present contribution is therefore addressed to investigate the consequence of Ti-6Al-4V powder recycling on the flowability, particle size distribution and morphology of the feedstock material as well as on the density and tensile performance of built parts. In order to quantify the recyclability of powders, a new "average usage time" (AUT) parameter is defined to account for both the real usage time of the powder and the virgin-to-used powder mixing ratio. The new parameter, whose applicability can be readily extended to any kind of feedstock powder, offers a significant contribution to achieve a more consistent and economical recycling of raw materials for PBF processing.

Middle carbon low alloyed steel 0.4C-0.6Mn-2Si was subjected to thermo-mechanical treatment typical for TRIP (transformation induced plasticity steels). The processing consisted from soaking at the temperatures of 850-1000 °C and cooling at 30 °C/s to various annealing holds in bainite transformation temperature interval of 350-500 °C. During the cooling from the soaking temperature, two compressive deformations were carried out, the second one always at 720 °C. Resulting microstructures were analysed using light and scanning electron microscopy. X-ray diffraction phase analysis was carried out to establish volume fraction of retained austenite and mechanical properties were measured by tensile test. Tensile strengths in the region of 847-963 MPa were obtained and very good total elongations of 30-40% were achieved at the same time. Multiphase microstructures were obtained with various amounts of ferrite, bainite, retained austenite and pearlite.

Like most new technologies, 3D printing has long been a domain of narrowly specialized fields. However, the potential of this technology is enormous and thus it has been gradually finding its application in ever-newer sectors. This paper focuses on the structure and overall implementation of a triaxle manufacturing device inspired by an existing 3D printer design based on the modular RepRap concept. The result is a functional triaxle manufacturing device capable of performing 3D printing and laser cutting or laser engraving.

Today, extensive information on a particular material can be obtained from its chemical composition using various computer programs. Such information includes phase transformation temperatures, such as Ac1 and Ac3 or the Ms and Mf, as well as the entire austenite decomposition sequence, as shown in TTT and CCT diagrams. When steel is heated, austenite grains begin to form, grow and eventually coarsen. On cooling, these grains decompose into pearlite, ferrite, cementite and hardening phases. Transformations of this kind are well understood nowadays, namely the ways the individual phases form and the rates and temperatures involved. Yet, in-situ visual recordings of such transformations are relatively rare. Using the Linkam TS1400XY heating stage, which is capable to heat samples up to 1400°C and is integrated in an optical microscope featuring objective lenses with modified working distances, these phase transformations can be observed directly. This paper explores the potential of the heating stage for studying various materials and their specific heat treatments. It also discusses the method of sample preparation for use in the heating stage placed in an optical microscope.

Forestry is characterized by a diversity of natural conditions, which need to be adapted not only to the selection and application of technological processes, but also to the materials used in the construction of individual parts of the equipment. The article deals with the possibility of replacing steel elements with aluminium ones for selected parts of the adapter frame designed for liquidation of forest fires. The aim is to achieve a gradual reduction in its total weight. The aluminium sheet AlSiMgMn EN AW-6082 was selected a replacement for the steel parts. The filler material was solid wire AlMg5Cr. Welding was performed by the MIG method. The selected welding parameters should guarantee the creation of a quality joint that can replace steel weld joints, while respecting the demands placed on them. Weld joints were analysed by macroscopic analysis, measurement of hardness by HV1 and SEM analysis of welded joint with EDX analysis. The results of the laboratory experiment show that by the chosen welding procedure with given parameters, quality welded joints were achieved. After further analyses, these weld joints can be recommended as a substitute for the previously used weld joints of steel structures.