In the present study, a large-area stir zone (SZ) was fabricated in AA2014 alloy using multi-pass friction stir processing (FSP) with pin overlapping. The microstructure evolution, crystallographic texture, precipitation phenomenon, and tensile behavior were studied and reported. The microstructure of the large-area SZ consists of equiaxed fine grains with a high density of high angle boundaries caused by dynamic recovery (DRV) and continuous-dynamic recrystallization (C-DRX), and the grain refining has been uniform in each overlapping pass (the grain size within 4-7 μm range). The material flow around the pin caused by the stirring action of the tool contributed to the creation of a strong Brass-{110}<112>and A-{110}<111>components in the first pass of SZ. Unlike first pass SZ, the second to fifth-pass SZ presents Copper-{112}<111>and Cube- {001}<100>components due to an increase of heat input by the shoulder to participate multiple times on each overlapping SZ. The hardness and strength of the FSP sample were found to be lowered relative to a base metal. Simultaneously, the SZ ductility increased after FSP by 155% due to the material softening and dissolution of Al2Cu precipitates in the SZ. Kocks-Mecking plots of the BM and FSP samples witnessed the Stage-III of work-hardening behavior. The fine-grain structure and precipitation phenomenon in the FSP sample resulted in better corrosion resistance than the base metal.
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In this work, the friction stir weldability of Ti6Al4V T-joints has been investigated. Its aims are: (i) to study the influence of tool and welding parameters on weld quality, (ii) to assess the joints’ mechanical strength to foresee future applications, and (iii) to characterize Co-based FSW tools’ wear by following the wear during the tests. Welds’ defectivity is studied by cross-section macrographies analysis. Independently from welding parameters and tools, internal voids are avoided, and a suitable weldability window is identified. Microstructure observations have corroborated temperatures below the -transus point even in the nugget zone, guaranteeing joints’ maximum mechanical strengths at 96% and 87% of the base material for UTS and Y, respectively. Contrarily, elongation at break is very low, without reaching 20% of the base material. The failure is linked to section thinning and kissing bond defects at the joints’ corners. Additionally, tool wear proved to be a critical issue while friction stir welding Ti6Al4V. The inner part of the shoulder is the most sensitive to wear. The consequent high wear rate might be a problem for mass production. The work established the pertinence of assembling complex geometries of Ti6Al4V using friction stir welding, considering weld quality and the mechanical strength achieved. However, critical factors such as section thinning, kissing bond, and tool wear must be carefully addressed to avoid joints’ low elongation at break and to guarantee their mechanical strength.
Zjawiska cieplne dotyczące odkształceń plastycznych mogą być powszechnie obserwowane. Wystarczy dotknąć zerwanej, czy zgiętej próbki, aby przekonać się, że w miejscu odkształcenia wzrosła temperatura. Obserwacje takie mogą być prowadzone w celu oceny jakościowej lub ilościowej. Niniejszy artykuł służy do jakościowego powiązania zmian zachodzących w strukturze odkształcanego materiału ze wzrostem temperatury zaobserwowanym przy użyciu kamery na podczerwień.
W pracy przedstawiono podstawowe informacje na temat zgrzewania tarciowego z przemieszaniem. Skupiono się na problemie, jakim są występujące podczas zgrzewania odkształcenia cienkościennych blach ze stopu 2024 T351. W celu zniwelowania deformacji zaprojektowano i wykonano uchwyt z płytą podgrzewającą elementy zgrzewane. Zabieg podgrzewania zgrzewanych blach ma na celu obniżenie naprężeń chwilowych, a co za tym idzie zmniejszenie ich a wykonywano przy tych samych parametrach.
EN
The paper depicts basic information concerning Friction Stir Welding. The main focus revolves around a problem which is deformation of thin-walled plates made out of 2024 T351 alloy which occurs when the plates are welded. In order to reduce these deformations a mount with panel that heats up welded elements has been designed and produced. The procedure of heating up welded plates intends to reduce temporary tensions and as a consequence of that it also reduces the deformation of the plates. All tests of welding were conducted under the same parameters.
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Understanding the microstructural and mechanical behavior of the friction stir welded magnesium matrix composites is necessary for different applications in automobile and aerospace components such as fuel tanks, steering wheels, chassis, seat frames, etc. In the present study, friction stir welding of magnesium RZ5/8 wt% TiB2 metal matrix composites is carried out at different joining conditions. FESEM micrograph showed the refined equiaxed grains in the nugget zone and elongated grains in the thermo-mechanically affected zone. Better grain refinement with uniform distribution is achieved at the tool rotational speed of 931 rpm and traverse speed of 20 mm/min. During the joining of RZ5/8 wt% TiB2 composites, the maximum temperature measured in the nugget zone is 511 °C at the rotational tool speed of 1216 rpm and traverse speed of 20 mm/min. Hardness is maximum at the nugget zone, which is 30% higher than the base material. The heat-affected zone showed the lowest hardness due to the annealing induced grain growth. Tensile strength is maximum during the joining of the RZ5/8 wt% TiB2 composites at a tool rotational speed of 931 rpm because of the better grain refinement with uniform reinforcement distribution in the weld zone. The tensile residual stress is observed to be a maximum of 71.41 MPa at a depth of 2.5 mm from the top surface and compressive residual stress of 60.98 MPa at the bottom surface of the nugget zone. The residual stress increased with an increase in tool rotational speed due to the increase in shrinkage of the materials at the higher temperature.
The aim of the study was to implement an integrally configured method of quality control of frictional welding of piston forgings intended for Diesel Man trucks. The use of the method (consisting of the 5W2H method, the Ishikawa diagram and the ABCD - Suzuki method) would contribute to the detection of the causes of non-compliance and consequently to the elimination of non-compliant products. Steel pistons have become the subject of research due to significant problems with maintaining their expected level of quality after the introduced structural and technological changes. The proposed method has helped to identify the root cause of non-compliance. It was: incorrect design of the combustion chamber in terms of diameter and depth. The study shows that it is advisable to use an integrated approach to finding the causes of quality problems on the example of the friction welding process. This was a new solution for the company, as no in-depth analyses of quality problems using a sequence of quality management techniques have been carried out so far.
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The evolution of microstructure and mechanical properties in AISI 8630 low-alloy steel subjected to inertia friction welding (IFW) have been investigated. The effects of three critical process parameters, viz. rotational speed, friction and forge forces, during welding of tubular specimens were explored. The mechanical properties of these weld joints, including tensile and Charpy V-notch impact were studied for determining the optimum welding parameters. The weld joints exhibited higher yield strength, lower hardening capacity and ultimate tensile strength compared to base metal (BM). The maximum strength and ductility combination was achieved for the welds produced under a nominal weld speed of ~ 2900–3100 rpm, the highest friction force of ~ 680–720 kN, and the lowest axial forging load of ~ 560–600 kN. The measured hardness distribution depicted higher values for the weld zone (WZ) compared to the thermo-mechanically affected zone (TMAZ), heat-affected zone (HAZ) and BM, irrespective of the applied welding parameters. The substantial increase in the hardness of the WZ is due to the formation of microstructures that were dominated by martensite. The observed microstructural features, i.e. the fractions of martensite, bainite and ferrite, show that the temperature in the WZ and TMAZ was above Ac3, whereas that of the HAZ was below Ac1 during the IFW. The fracture surface of the tensile and impact-tested specimens exhibited the presence of dimples nucleating from the voids, thus indicating a ductile failure. EBSD maps of the WZ revealed the formation of subgrains inside the prior austenite grains, indicating the occurrence of continuous dynamic recrystallisation during the weld. Analysis of crystallographic texture indicated that the austenite microstructure (i.e. FCC) in both the WZ and TMAZ undergoes simple shear deformation during IFW.
Friction welding is one of the most economical process of joining solid-state materials. This technique allows to weld similar and dissimilar materials in a very short time. Friction welding of metal with composites gives new possibilities of application, due to the fact that materials have different physical and mechanical properties. In the study, aluminum alloy 44200 was friction welded to Al/Al2O3 composite. In addition, the following inspections were performed: optical microscopy, microhardness measurements and also tensile strength for all joints produced by friction welding. All of the studies were performed to evaluate the quality of connection between the 44200 alloy and the composites on the aluminum alloy matrix reinforced with ceramic phase of Al/Al2O3.
PL
Zgrzewanie tarciowe to jedna z bardziej ekonomicznych metod trwałego łączenia materiałów w stanie stałym. Metoda ta umożliwia wykonywanie złączy zarówno jednoimiennych, jak i różnoimiennych w bardzo krótkim czasie. Zaletą zgrzewania tarciowego jest możliwość uzyskania złączy o wysokiej jakości. Zgrzewanie tarciowe kompozytów z metalami, stwarza nowe możliwości aplikacji, z uwagi na fakt, że oba materiały posiadają różne właściwości fizyczne oraz mechaniczne. W pracy przeprowadzono próby spajania stopu aluminium EN-AC-44200 z kompozytami Al/Al2O3. W opracowaniu przeprowadzono następujące badania złączy stop aluminium-kompozyt uzyskanych metodą zgrzewania tarciowego: mikroskopowe, twardości, mechaniczne (pomiar wytrzymałości na rozciąganie). Wykonane badania miały na celu ocenę jakości połączenia pomiędzy stopem 44200, a kompozytami na osnowie stopu aluminium wzmacnianymi fazą ceramiczną Al/Al2O3.
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W artykule opisano innowacyjną technologię zrobotyzowanego przygrzewania tarciowego kołków stalowych do powierzchni blach i płyt konstrukcji ze stali HSS i UHSS we wszystkich pozycjach zgrzewania.
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Direct-drive friction welding of ASTM A106 and AISI 4140 steel tubes has been investigated both experimentally and numerically. A remeshing technique was implemented to accurately simulate highly distorted flashes during the FE simulation. The results revealed that the circumferential thermal expansion led to a higher contact pressure at the inner diameter of the interface and consequently, inner flashes were formed up to 18% larger than the outer ones. The maximum temperature was also located at the outer diameter of the interface in the first moments of the process, then it moved towards the center of the section where there was a balance between the higher slipping rate at the outer section and greater pressure at the inner section of the joint. Validation tests showed the capability of the FE model in terms of temperature, flash cross-section, and axial shortening with the maximum difference of 18.6%.
In order to meet the current requirements of the automotive industry, associated with the creation of a machining center for the production of cylindrical welded and turned components for the construction of solenoid valves, innovative technologies are needed for joining different materials of construction. The article presents the results of the research on the applicability, production of steel electrovalves elements in the AISI303 and 11SMnPb30 grades, an innovative solution consisting in the combination of HSFW high speed friction welding and friction welding using the FSW method. As part of the research, inter alia, a welding station, selection of the shape and dimensions of tools, selection of welding parameters for the HSFW / FSW method, and tests of mechanical properties of the resulting joints were carried out. The obtained results indicate that the obtained connections are characterized by high and reproducible quality.
PL
W celu spełnienia obecnych wymagań branży motoryzacyjnej, związanych ze zbudowaniem centrum obróbczego do wytwarzania cylindrycznych komponentów zgrzewanych i toczonych do budowy elektrozaworów, potrzebne są innowacyjne technologie łączenia różnoimiennych materiałów konstrukcyjnych. W artykule przedstawiono wyniki badań dotyczące możliwości zastosowania, do produkcji elementów elektrozaworów ze stali w gat. AISI303 oraz 11SMnPb30, innowacyjnego rozwiązania polegającego na połączeniu technologii zgrzewania tarciowego wysokoobrotowego HSFW oraz zgrzewania tarciowego metodą FSW. W ramach badań opracowano m.in. stanowisko do zgrzewania, dokonano doboru kształtu i wymiarów narzędzi, doboru parametrów zgrzewania dla metody HSFW/FSW oraz przeprowadzono badania własności mechanicznych powstałych złączy. Uzyskane rezultaty wskazują, że otrzymane połączenia cechują się wysoką i powtarzalną jakością.
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W artykule opisano innowacyjną technologię zrobotyzowanego przygrzewania tarciowego kołków stalowych do powierzchni blach i płyt konstrukcji ze stali HSS i UHSS we wszystkich pozycjach zgrzewania. Podano podstawowe parametry procesu przygrzewania tarciowego kołków stalowych do blach i płyt ze stali HSS i UHSS. Proces ten zapewnia znaczne zwiększenie jakości i własności mechanicznych złączy kołek + blacha lub płyta, dużą łatwość sterowania parametrów zgrzewania i monitorowania jakości procesu zgrzewania, jak i wysoką ekonomiczność oraz bezpieczeństwo pracy. Opisano stanowisko do zrobotyzowanego przygrzewania tarciowego kołków wyposażone w system monitorowania i sterowania jakością złączy zgrzewanych w czasie rzeczywistym.
AA7075 is an aluminum alloy which is almost as strong as steel, yet it weighs just one third as much. Unfortunately its use has been limited, due to the fact that pieces of it could not be securely welded together by the traditional welding process. Friction Stir Welding (FSW) process overcomes the limitations of conventional welding process. In our present work we have used Artificial Neural Network which is Artificial Intelligence based technique used for prediction purpose. The main objective of our present work is to compare the predicted results of the Ultimate Tensile Strength (UTS) of Friction Stir welded similar joints through Regression modeling and Artificial Neural Network (ANN) modeling. It was observed that the linear regression algorithm is able to make more accurate predictions compared to neural network algorithm for small dataset.
Purpose: This work aims to investigate the microstructure and mechanical properties achieved by FSW of butt joints, namely of dissimilar sheets namely of 2014-T3 to 5059-H11 Al alloys by bonding the two materials perpendicular to their rolling directions. Design/methodology/approach: AA 2014T3 and AA 5059H11 were two dissimilar aluminium alloys friction stir welded. The joint has been examined in terms of hardness, microstructure, and mechanical properties. The microstructure of the weld area was characterized by using optical microscopy. Seven diverse regions of the microstructure in the joint can be illustrious. Findings: It has been noticed that a structure of fine grain is formed in the nugget region as a consequence of recrystallization. The thermos mechanically affected and heat affected zones of aluminium alloy 2014 are characterized by the lowest hardness values in spite of there are a general hardness decrease through the weld zone compared to both base metals. The ultimate tensile strength values of the dissimilar joint were found to be varying between 54% to 66% those of the base metal. Research limitations/implications: The t joining in FSW takes place with the base materials remnant in the solid state, which gives a considerable possibility to produce joints between the alleged difficult-to-weld heat treatable aluminium alloys. Originality/value: The outcomes display that friction stir welding can be effectively applied for the joining of dissimilar aluminium alloys.
Welding strength is very important in safe use of polypropylene sheets. The determination of welding parameters and design of the welding tool has an impact on the weld strength. The welding parameters can be determined experimentally. In this study, Charpy impact test is used to determine suitable welding parameters in welding of polypropylene sheets with FSW method. At the same time, the weld zone microstructure is examined and Shore hardness measurements are made. The impact tests were performed on samples cut from the welded sheets. The impact tests values and hardness values were presented graphically. According to the test results, some welded parts behaved similar to the matrix material. In some welding parameters, Charpy impact test values were obtained close to values of the main materials. The suitable welding parameters were determined for polypropylene sheets welding.
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The effect of bead on plate friction stir welding parameters on the tensile properties of the 70/30 brass joints was investigated using response surface method. The microstructures of the joints were characterized using optical microscopy, electron backscattered diffraction (EBSD), and transmission electron microscopy (TEM). The tensile test was conducted to measure the ultimate tensile strength and elongation of the joints. In addition, the fracture surfaces of the tensile specimens were analyzed by scanning electron microscopy (SEM). The results showed that the most effective parameters on the strength and elongation of the joints were tool rotational speed and axial force, respectively. Optimizing the parameters revealed that the maximum strength and elongation of 318.5 MPa and 54.9% can be achieved at a rotational speed of 1000 rpm, a traverse speed of 58.4 mm/min, and an axial force of 3 kN. The strengthening mechanisms of grain boundary and dislocation density effects were responsible for the higher ultimate tensile strength of the joints welded at the lower heat input conditions. Furthermore, the effect of friction stir parameters on the ultimate tensile strength and elongation of the joints has been discussed, thoroughly.
Friction stir welding (FSW) is a solid state joining process used to join metals and their alloys. The main goal of this paper was to select the optimal welding parameters such as: rotational speed and the feed rate of the tool. The article presents the results of the tests on welding 1 mm thick 2024 aluminum sheet according to the statistical 3-level completed plan PS/DK 32. The rotational speed of the tool varied within the range of 1100–1300 rpm and the feed rate within the range of 40–60 mm/min. For these parameters, the analyses of the experiment repeatability, impact significance and adequacy of equations were conducted.
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W artykule opisano stosowane aktualnie w przemyśle technologie spawania termitowego i zgrzewania oporowego iskrowego szyn trakcji kolejowych dużej prędkości oraz nowoczesne stale niskostopowe bezwęglikowe bainityczne, zapewniające wysokie własności mechaniczne i trybologiczne szyn. W celu znacznego zwiększenia jakości złączy doczołowych szyn i ekonomiczności procesu łączenia zaproponowano dwie innowacyjne technologie łączenia szyn: spawanie laserowe oraz zgrzewanie tarciowe wibracyjne.
EN
The article describes currently used technologies of the thermite welding and resistance flash welding of the butt joints of high-speed rails and modern low-alloy, carbidefree bainitic steels, that ensure high mechanical and tribological properties of rails. In order to significantly increase the quality of the butt joints of rails and the cost-effectiveness of the joining process, two innovative rail joining technologies have been proposed: laser welding and vibration friction welding.
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W artykule omówiono problematykę zgrzewalności metali o ultradrobnoziarnistej strukturze. Problem omówiono na przykładzie stali 316L o ultradrobnoziarnistej strukturze uzyskanej na drodze obróbki plastycznej hydrostatycznego wyciskania. Złącza uzyskano metodą zgrzewania tarciowego. Parametry zgrzewania dobierano wg kryterium najniższego stopnia rekrystalizacji obszaru złącza. Wykonano badania metalograficzne, scharakteryzowano wybrane obszary złącza zgrzewanego pod względem twardości i zasięgu zmiękczenia materiału. Wykonano próby statycznego rozciągania, porównano wytrzymałość na rozciąganie materiału rodzimego oraz złącza zgrzewanego.
EN
The article discusses the issues of weldability of metals with UFG (ultrafine grained) metals. The problem was discussed on the example of 316L steel with UFG structure obtained by metal forming method of hydrostatic extrusion. The joints were obtained by friction welding. Welding parameters were selected according to the criterion of the lowest degree of recrystallization of the joint area. Metallographic examinations were performed, selected areas of the joint welded in terms of hardness and range of softening of the material. Static tensile tests were carried out, the tensile strength of the parent material and the welded joint were compared.
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Stosowanie podgrzewania prowadzi do niwelacji odkształceń plastycznych zgrzewanych cienkościennych blach metodą FSW. Podgrzewanie to podwyższa temperaturę procesu, umożliwiając stosowanie większych prędkości posuwowych, a co za tym idzie – skraca jego czas. Badania złącza wykonanego przy jednakowych parametrach wykazały znacznie większą wytrzymałość na rozciąganie w przypadku zgrzewania z zastosowaniem podgrzewania. Badania przeprowadzone kamerą termowizyjną ukazały proces rozchodzenia się ciepła. Zauważono, że temperatura w początkowych fazach zgrzewania jest znacznie niższa, co bez wątpienia powoduje powstawanie złącza o niższej wytrzymałości.
EN
The use of heating leads to reducing plastic deformations of thin sheets welded by the FSW method. Preheating increases the process temperature and allows higher feed rates to be used, thus reducing the time of the process. Tests made on connections with the same parameters showed much higher tensile strength in the case of using heating. Thermal imaging studies have shown the heat dissipation process and it has been noticed that the initial temperature is significantly lower, which undoubtedly results in the formation of a lower strength weld.
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