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PL
W artykule przedstawiono wyniki drugiego etapu prac nad wpływem kształtu rolek prostownic na stan naprężeń własnych w szynach prowadzonych w ramach projektu dofinansowanego przez Narodowe Centrum Badań i Rozwoju. Badania obejmowały symulacje numeryczne procesu prostowania szyn z zastosowaniem nowego kalibrowania rolek prostownicy pionowej oraz poziomej, wyznaczenie map rozkładu naprężeń w szynie po prostowaniu w kolejnych rolkach obu prostownic, a także pomiary naprężeń własnych w szynach po operacji prostowania w warunkach przemysłowych. Badania wykonano na szynach typu 60E1 w gatunku R260. Uzyskano zmniejszenie naprężeń własnych rozciągających w środku osi symetrii stopki szyny, aż do średnich wartości 32 MPa tj. o ponad czterokrotnie mniej w stosunku do poziomu osiąganego przy użyciu tradycyjnej technologii.
EN
The paper presents the results of the second stage of work on the influence of the shape of straightening rollers on the state of residual stresses in rails, conducted as part of a project co-financed by the National Centre for Research and Development. The tests included numerical simulations of the rail straightening process using a new roll pass design of vertical and horizontal straightener rollers, determination of stress distribution maps in the rail after straightening in successive rollers of both straightening machines, as well as measurement of residual stresses in the rails after straightening operation in industrial conditions. The tests were carried out on R260 grade 60E1 rails. The reduction of tensile residual stresses in the centre of symmetry axis of the rail foot was obtained up to an average level of 32 MPa, i.e. by more than four times less in relation to the level achieved using traditional technology.
PL
W artykule przedstawiono wyniki trzeciego etapu prac nad wpływem nowego kalibrowania rolek prostownic na stan naprężeń własnych w szynach kolejowych prowadzonych w ramach projektu dofinansowanego przez Narodowe Centrum Badań i Rozwoju. Badania obejmowały symulacje numeryczne procesu prostowania szyn z zastosowaniem innowacyjnego kształtu rolek prostownicy pionowej oraz poziomej, wyznaczenie map rozkładu naprężeń w szynie po prostowaniu w kolejnych rolkach obu prostownic, a także pomiary naprężeń własnych w szynach po operacji prostowania w warunkach przemysłowych. Badania przeprowadzono na szynach o długości 120 metrów typu 60E1 w gatunku stali R260. Uzyskano znaczące zmniejszenie naprężeń własnych rozciągających w środku osi symetrii stopki szyny oraz w główce szyny w stosunku do poziomu określonego w normie EN 13674-1.
EN
In this paper the results of the third stage of works on the influence of the shape of straightening rollers on the state of residual stresses in railway rails conducted as part of a project co-financed by the National Centre for Research and Development are presented. The performed tests included numerical simulations of the straightening process of rails using a new roll pass design of vertical and horizontal straightener rollers, determination of stress distribution maps in the rail after straightening in successive rollers of both straightening machines, as well as measurements of residual stresses in rails after straightening operation in industrial conditions. The tests were carried out on 120 meters long rails type 60E1 in the R260 steel grade. Obtained the significant reduction of tensile residual stresses in the centre of symmetry axis of the rail foot as well as of the rail head in relation to the level specified in the standard EN 13674-1.
EN
Industries that rely on additive manufacturing of metallic parts, especially biomedical companies, require material science-based knowledge of how process parameters and methods affect the properties of manufactured elements, but such phenomena are incompletely understood. In this study, we investigated the influence of selective laser melting (SLM) process parameters and additional heat treatment on mechanical properties. The research included structural analysis of residual stress, microstructure, and scleronomic hardness in low-depth measurements. Tensile tests with specimen deformation analysis using digital image correlation (DIC) were performed as well. Experiment results showed it was possible to observe the porosity growth mechanism and its influence on the material strength. Specimens manufactured with 20% lower energy density had almost half the elongation, which was directly connected with the porosity growth during energy density reduction. Hot isostatic pressing (HIP) treatment allowed for a significant reduction of porosity and helped achieve properties similar to specimens manufactured using different levels of energy density.
4
Content available remote Guidelines to select suitable parameters for contour method stress measurements
EN
The contour method is one of the promising techniques for the measurement of residual stresses in engineering components. In this method, the cut surfaces deform, owing to the relaxation of residual stresses. The deformations of the two cut surfaces are then measured and used to back calculate the 2-dimensional map of original residual stresses normal to the plane of the cut. Thus, it involves four main steps; specimen cutting, surface contour measurement, data analysis and finite element simulation. These steps should perform in a manner that they do not change the underlying features of surface deformation especially where the residual stress distribution varies over short distances. Therefore, to carefully implement these steps, it is important to select appropriate parameters such as surface deformation measurement spacing, data smoothing parameters (‘knot spacing’ for example cubic spline smoothing) and finite element mesh size. This research covers an investigation of these important parameters. A simple approach for choosing initial parameters is developed based on an idealised cosine displacement function (giving a self-equilibrated one-dimensional residual stress profile). In this research, guidelines are proposed to help the measurer to select the most suitable choice of these parameters based on the estimated wavelength of the residual stress field.
EN
The titanium alloys are materials susceptible to tribological wear and the laser treatment can be applied in surface treatment processes to obtain for example higher hardness level. From the other side, it is important to take into consideration, that hardness increase that can be connected with cracks . The aim of this research was to investigate the effects of different lasers and the process parameters on the form and level of residual stresses in the Ti6Al4V alloy, which determine the initiation and propagation of cracking. Two lasers were used, the CO2 and Nd:YAG lasers. The specimens were remelted in liquid nitrogen, water or calm air at different pre-heating temperature. The different laser power and scan rates were applied. The increase in energy density increased the number of cracks, the change of an environment and pre-heating affected alo the surface cracking. The cracks observed after remelting with Nd:YAG laser were longer than those observed after treatment with CO2 laser. The compressive stresses after the CO2 laser treatment, and tensile stresses after treatment with the Nd:YAG laser, were found. The appearance of cracks was attributed to an excessive energy density. The different distribution of heat energy inside and around the laser tracks was discussed as the origin of presence either tensile or compressive stresses in the alloy treated with different lasers.
PL
Blachy krzemowe o zastosowaniach elektrotechnicznych są produkowane ze względu na przeznaczenie. W obwodach magnetycznych transformatorów struktura blach jest projektowana ze względu na zgodność kierunku magnesowania z kierunkiem wektora indukcji. Są to blachy o strukturze zorientowanej (GO - e.g. anisotropic transformer sheets). W napędach przetwarzających energię pola magnetycznego na ruch obrotowy stosujemy blachy o strukturze niezorientowanej (NGO - e.g. isotropic or generator sheets). Defekty struktury będące wynikiem cięcia lub wycinania (dowolnymi technikami mają wpływ na deformację kierunku magnesowania bez względu na stosowane techniki cięcia. W procesie tym uczestniczą zjawiska magnetosprężyste i odwrotne, znane jako efekty Vilariego i Joule’a. W artykule opisano kierunkowe zmiany magnesowania na dwóch modelach testowych przygotowanych z blachy krzemowej M130 w obszarze materiałowym, elektrotechnicznym i mechanicznym, a także w obszarze badań nieniszczących NDT (Non-destructive testing) i SHM (Structural health monitoring) monitorowanie stanu strukturalnego SHM, a także monitorowanie stanu w procesie eksploatacji (ang. Condition Monitoring - CM).
EN
Silicone sheets for electrical purposes are made for their intended purpose. In transformer magnetic circuits, the sheet structure is designed due to the compatibility of the direction of magnetization with the direction of the induction vector. These are oriented metal sheets (for example, anisotropic transformer sheets). In drives that convert the energy of a magnetic field into rotational motion, we use plates with a non-oriented structure (NGOs — for example, isotropic or generator sheets). Design defects resulting from cutting or cutting (using any methods that affect the deformation of the magnetization direction, regardless of the cutting methods used.) This process includes magneto-elastic and backward effects, known as the Vilary and Joule effects. tests prepared from silicon steel sheet M130 in the material, electrical and mechanical fields, as well as NDT (non-destructive testing) and SHM (Structural health monitoring), monitoring the state of structures SHM, and monitoring the state (Condition Monitoring - CM).
EN
The production of two-wheeled rolling stock represents, at first glance, a simple assembly process that significantly affects the overall functionality and safety of the vehicle. This is due to residual stresses that arise after assembly by pressing the wheel on the axle. The state of stress after assembly remains in the design has a decisive influence on the load-bearing capacity of the two-wheel drive, its lifespan but also the transfer of the pulling force in the case of locomotives. Therefore, it is very important to find suitable methods for determining residual stresses. Numerical and experimental approaches are already in place to gain information on the state of stress after compression, or during a real operation. The developed techniques and tools for estimation of residual stresses in locomotive wheel treads based on the acoustoelasticity effect using electromagnetic acoustic transformation are described in the paper. The original results of residual stress measurement in the treads during a technological cycle of locomotive wheel pair manufacturing are presented.
EN
In the present research, a parametric study in Resistance Spot Welding (RSW) of thin AISI 1008 steel sheets is investigated via FEM. All the time steps through the RSW process, including squeeze time, welding time, holding time and cooling time are taken into account. First, the effects of various parameters such as electrical current, welding time and electrode tip diameter are investigated in the nugget geometry. Then, a time history stress diagram and residual stresses are obtained in RSW weldment. FEM results are validated very well by some experiments which were performed in two parts of nugget geometry and residual stresses.
PL
W pracy przedstawiono wyniki pomiarów naprężeń własnych odpowiednio przygotowanych próbek tytanu Grade 5 (Ti6Al4V). Próbki były uprzednio kulowane śrutem stalowym o średnicach 0,6 mm, i 1,2 mm i twardości 640 HV. Przeprowadzono pomiary naprężeń własnych metodą Waismana-Philipsa polegającą na pomiarze strzałki ugięcia próbki w próbie trawienia stopu tytanu Ti6Al4V w roztworze kwasu fluorowodorowego (HF) i siarkowego (H2SO4). Badanie przeprowadzono na stanowisku zaprojektowanym i wykonanym wcześniej w Instytucie Mechaniki Precyzyjnej (IMP). W celu oceny wpływu parametrów procesu kulowania na próbki wykonano pomiary chropowatości ich powierzchni przed trawieniem. Wyznaczenie wartości i rozkładów naprężeń własnych sprowadza się, jak nadmieniono, do określenia zmian krzywizny w funkcji zmian grubości badanej próbki, a następnie wykonaniu niezbędnych obliczeń. Wyniki pomiaru przemieszczeń w funkcji czasu oraz grubości próbek uzyskane po trawieniu posłużyły do wyznaczenia wartości naprężeń własnych w funkcji odległości od powierzchni próbki. Obliczenia wykonano przy pomocy programu NWW 11.
EN
The paper presents results of measurements of residual stresses of the properly prepared Grade 5 titanium (Ti6Al4V) samples. The samples previously underwent the process of shot-peening with steel shots with 0.6 mm, and 1.2 mm in diameter and 640 HV hardness. Measurements of residual stresses were carried out using the Waismman-Philips method consisting in measuring the sample deflection arrow in the etching test of Ti6Al4V titanium alloy in the solution of hydrofluoric acid (HF) and sulfuric acid (H2SO4). Tests were carried out on the stand designed and constructed earlier at the Institute of Precision Mechanics (IMP). In order to assess the impact of the shot-peening process parameters on the samples, roughness measurements of the surface before etching were carried out. Determining the values and distributions of the residual stresses is reduced, as mentioned, to determining the changes in curvature as a function of changes in the thickness of the sample tested, and then conducting the necessary calculations. The results of the measurement of displacements as a function of time and thickness of the samples obtained after etching were used to determine the value of residual stresses as a function of distance from the sample surface. Calculations were conducted with using the NWW.11 program.
PL
W artykule przedstawiono wyniki pierwszego etapu prac nad wpływem kształtu rolek prostownic na stan naprężeń własnych w szynach prowadzonych w ramach projektu dofinansowanego przez Narodowe Centrum Badań i Rozwoju. Wykonane badania obejmowały symulacje numeryczne procesu prostowania szyn z zastosowaniem nowego kalibrowania rolek prostownicy pionowej, wyznaczenie map rozkładu naprężeń w szynie po prostowaniu w kolejnych rolkach, pomiary naprężeń własnych w szynach po operacji prostowania w warunkach przemysłowych. Badania przeprowadzono na szynach typu 60E1 w gatunku R260. Uzyskano zmniejszenie naprężeń własnych rozciągających w środku osi symetrii stopki szyny o ponad 52% w stosunku do poziomu osiąganego.
EN
In this paper the results of the first stage of works on the influence of the shape of straightener rollers on the state of residual stresses in rails conducted as part of a project co-financed by the National Center for Research and Development are presented. The performed tests included numerical simulations of the straightening process of rails using a new roll pass design of vertical straightener rollers, determination of stress distribution maps in the rail after straightening in successive rolls, measurements of residual stresses in rails after straightening operation in industrial conditions. The tests were carried out on 60E1 rails in the R260 grade. The reduction of tensile residual stresses in the center of symmetry axis of the rail foot was obtained by over 52% in relation to the level achieved during straightening with the use of traditional rollers.
EN
The article presents results of investigation of residual stresses for multi-layer circumferential welds of oil and gas pipelines. The research was carried out on a designed and manufactured testing equipment for the experimental determination of the stress state parameters in the zone of multi-layer welded joints of pipe segments with the external diameter of 1020 mm and the wall thicknesses of 9.5 mm, of 14 mm, and of 22 mm which were made of carbon steels of different quality (13G1S, 13G1SU, 17G1S and 17G1SU). Determination of residual stresses in the zone of multi-layered circumferential welds of pipe segments was carried out by means of the method by the electronic speckle-interferometry and by the method of magnetoelasticity. On the basic of analysis of the obtained graphic dependences, the recommendations for engineering practice are suggested.
EN
In the current research the hydrostatic extrusion (as one of the most common method of grain refinement) of the commercial 1.4462 duplex stainless steel was carried out using several reduction stages leading to a cumulative deformation strain ɛ = 1.4, and then ɛ = 3.8. The extrusion process has led to a change of microstructure and texture of the investigated material as was expected. Moreover, these changes were accompanied by improvements in mechanical properties measured by the nanohardness. The aim of this research was the characterization of the texture, residual stress and mechanical properties after subsequent stages of deformation.
EN
The results of experimental studies on the dependence of the thickness of amorphous-crystalline Zr-Al-B coatings on the value and level of distribution of type 1residual stresses were presented. It was demonstrated that residual compressive stresses arise in the surface layers of coatings, which in absolute value are not significant for its integrity and quality. It was established that the amorphous-crystalline composition, under the conditions of minimizing residual stresses and the optimal combination of the volume fraction of components, the structure and morphology of their components, has the best surface strength and wear resistance under friction compared to tungsten carbide and iron coatings
EN
The article presents the results of studies on the formation of residual stresses due to finish burnishing. Improper state of stresses may arise when, seeking higher dimension and shape accuracy, smaller roughness, or improved plateau area, the production engineer is willing to apply high and very high burnishing forces Fb. Plastic deformations in roughness created by burnishing can be easily measured with modern profilometers. However, each finish burnishing cut is accompanied by a state of stresses, some of which are residual stresses that remain in the item after machining. Excessively high stresses during the use of products are often causes of the cracking and flaking of surface fragments [1, 2]. One of most accurate methods for the evaluation of residual stresses after burnishing is their modelling taking into account the mechanical properties of material and technological parameter values used in the course of machining. The authors discuss the method of developing an experimental model, its testing, and verification of the results.
PL
W artykule zaprezentowano wyniki badań nad konstytuowaniem stanu naprężeń trwałych w skutek gładkościowego nagniatania. Nieodpowiedni stan naprężeń może powstać podczas sytuacji, w której dążąc do uzyskania coraz wyższej dokładności wymiarowo-kształtowej, mniejszej chropowatości czy też polepszenia nośności powierzchni technolog skłonny jest w zabiegu nagniatania stosować wysokie i bardzo wysokie siły nagniatania Fb. Deformacje plastyczne chropowatości powstałe wskutek nagniatania łatwo można zmierzyć, korzystając ze współczesnych profilometrów. Jednak każdemu zabiegowi nagniatania gładkościowego towarzyszy pewien stan naprężeń, z których część w formie naprężeń trwałych pozostaje w przedmiocie po zakończeniu procesu obróbki. Naprężenia trwałe o zbyt wysokiej wartości w trakcie eksploatacji wyrobów są często źródłem pękania i łuszczenia się fragmentów powierzchni [1, 2]. Jedną z dokładniejszych metod oceny stanu naprężeń trwałych po nagniataniu jest ich modelowanie przy uwzględnieniu własności mechanicznych materiału i wartości parametrów technologicznych stosowanych w trakcie obróbki. O sposobie przygotowania modelu doświadczalnego, jego badaniach i weryfikacji uzyskanych wyników autorzy dokładniej piszą w dalszej części artykułu.
PL
Celem pracy było omówienie istotnych aspektów pomiarów naprężeń w osiach kolejowych wykonywanych zgodnie z PN-EN 13261+A1:2011 na podstawie doświadczeń nabytych podczas prowadzenia pomiarów naprężeń w osiach kolejowych w akredytowanym Laboratorium Metaloznawstwa i Analiz Chemicznych (AB 394). Przedstawiono wymogi normy PN-EN 13261+A1:2011 pkt 3.6 dotyczące naprężeń szczątkowych (własnych) i opisano rentgenowską metodę ich pomiaru. Zestawiono wyniki pomiarów naprężeń w osiach kolejowych różnych typów wytworzonych przez czterech producentów oraz zależność wielkości naprężeń od parametrów toczenia i zużycia narzędzia. Stwierdzono, że o ile pomiar naprężeń na głębokości 2 mm może być wykonywany dla jednej osi z serii, to pomiar naprężeń na powierzchni powinien być wykonywany wyrywkowo dla pewnej ilości osi w serii.
EN
The aim of the work was to discuss important aspects of stress measurements in railway axes, according to PN-EN 13261 + A1: 2011 based on experience acquired during stress measurements in railway axes in the accredited Laboratory of Metal Science and Chemical Analysis (AB 394). The requirements of the PN-EN 13261 + A1: 2011 standard 3.6 regarding residual stresses and the X-ray method for their measurement are presented. The results of measurements of stresses in railway axes of various types made by four different manufacturers and the dependence of the magnitude of stresses are summarized from turning parameters and tool wear. It has been found that while stress measurement at a depth of 2 mm can be performed for one axis in a series, stress measurement on the surface should be performed randomly for a certain number of axes in a series.
EN
This paper presents the results of analysis of commercial CuSn6 alloy in form of strips at semi-hard state, plastically deformed in the process of repetitive corrugation. The influence of process parameters on the value of residual stresses and texture of examined material was investigated. As a result of residual stress analysis, the presence of compressive stresses for all analysed samples, regardless of the method of plastic working and direction of measurement, was confirmed. The distribution and the value of the stresses depend on the applied deformation process. Texture analysis shows that in the classically rolled strip, in addition to the Brass {110}<112> component, also the Goss {110}<001> and Copper {112}<111> components are present, and their contribution diminishes with the increase in the number of cycles of repetitive corrugation process. After intense plastic deformation the strip is characterised by two distinct texture components, {110}<112> and {110}<111>.
EN
Twist extrusion is a processing method involving the extrusion of a sample with a prismatic cross-section using a tool composed of four prismatic parts bisected by a screw component. A beneficial change in mechanical durability is one of the main factors enabling the use of highly durable Al-Mg-Mn-Sc-Zr alloys to construct functional components of non-stationary robots. As part of the present research, ANSYS® software was used to simulate a twist extrusion process. An analysis of a sample entering and passing through the entire twisting area was performed, up to the point of full twisting of the base of the sample. The stress conditions in the sample were analysed as it passed through the twisting area. The highest stress values (reaching up to 600 MPa) were detected at the tips of the sample face as the sample exited the twisting area. The lowest stress values, at around 170 MPa, were detected at the side edges of the sample.
EN
Conventional shot peening (SP) is cheap surface treatment widely used to enhance fatigue life of mechanical components [3,4]. Basically, it is shooting small particles (shots) on the surface of the sample. However, the process itself is so complex that a lot of companies are not able to optimally employ it due to the amount of parameters that must be controlled all at the same time. The duplex process consists in two stages of shot-peening treatment. The first one consist of shot-peening with spherical cast steel shots or cut wire shots. During the second stage the samples processed in stage one were subject to shot-peening with glass beads. In this work, RSA-501 aluminium alloy was shot peened using shots of different material and diameter and tested using a measurement of residual stresses and surface roughness. Tests and studies conducted so far on RSA-501 aluminium alloy demonstrate that bombardment by a treatment medium in the form of glass beads or shots of various shapes and diameters induces permanent plastic deformation of the surface layer. The roughness achieved after the shot-peening process was determined for each treatment medium. The largest value of Ra parameter was achieved for cut wire shots and this result is consistent with the above-mentioned theoretical knowledge. This medium is the most aggressive one to the surface being treated primarily due to the sharp edges of shots. The duplex process was successful in obtaining higher values of compressive stresses in surface layer than values achievable in conventional single-stage shot peening process.
EN
Ni3Al coatings were obtained on AISI 321 steel samples by air plasma spraying system. The behavior of heat treatment on intermetallic coatings were evaluated after exposure at various temperatures i.e. 500ºC to 800ºC. The stay time in this regard was varied from 10 to 100 hours. The coatings were then characterized by X-Ray diffraction analysis, optical and scanning electron microscopy, eddy current measurements and stress analysis. It was observed that the formation of NiO increases drastically with time and temperature. The hardness of the coating increases with the formation of NiO. It was noted that the residual stresses can be correlated with the formation of NiO. Further, the development of residual stresses can be monitored by a non-destructive technique i.e. eddy current method.
EN
The paper deals with the measurement of the residual stresses in P91 welded pipe using the blind hole drilling technique. The P91 pipe weld joints were prepared using gas tungsten arc welding process. The residual stress measurement was carried out using the strain gauge rosette that was associated with the plastic deformation of material and stress concentration effect of multi-point cutting tool. Strain gauge response was estimated experimentally using the tensile testing for the uniaxial loading while finite element analysis was performed for biaxial loading. Gas tungsten arc welds joint was prepared for conventional V-groove and narrow groove design. The corrective formulation was developed for calculating the corrected value of residual stresses from the experimentally obtained strain value. The corrected and experimental induced residual stresses values as per ASTM E837-13 were calculated for both V-groove and narrow groove design. Post weld heat treatment (PWHT) of P91 welded pipe was also conducted to study their effect on residual stresses.
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