The paper presents the results of finite element analysis of plastic deformation in the contact zone of dissimilar superalloys subjected to pressure welding. The results are compared for the two cases: with and without relief on the surfaces of parts to be welded. It is shown that the relief made on the surface can either decrease or increase the area of deformation stagnant zones, depending on the relief shape. The results of simulations are compared with the experimental test results.

Both the ultrafine-grained (UFG) structure with a grain size (d) less than 1 μm and nanocrystalline (NC) structure (d ≤ nm) can be processed in nickel-based alloy 58Ni-Cr-MoB -Al-Cu using methods severe plastic deformation, in particular, multistep isothermal forging within the temperature range of γ+δ-region on Bridgman anvils at strains е=5,5. Pressure welding performed under conditions of low temperature superplasticity (T=800°C, έ=10-4 s-1) can provide solid state joining of the alloy under study being in different structure conditions as well as joining of samples with coarse-grained structure using a NC layer.

The behavior of a material in extreme regimes of operation in large constructions can be calculated with the use of modern software codes (ANSYS, DEFORM, LS-Dyna). However, they do not have a sufficient basis for the properties of metals and alloys. Therefore, it is necessary to input experimental mechanical properties of a studied material for an adequate description of a process. The present work aims to obtain the mechanical properties of babbit Sn 11 % Sb 5,5 % Cu in different structural states for a use in computer modeling in the software product Deform. As an object of the study, babbit of a chemical composition Cu 5.5 -6.5 wt. %, Sb 10 -12 wt. %, Sn -rest was chosen. Two different structural states of the alloy were obtained at different crystallization rates: the first by casting with air cooling and the second by casting with cooling in running water (rapid cooling). The mechanical properties were determined by upsetting tests according to standart. An Axiovert-100A microscope with the KSLite image processing program was used for optical metallography. A finite element simulation of a large-sized sliding bearing during operation in a two-dimensional formulation was carried out using the DEFORM-2D software. To evaluate the degree of destruction of the bearing during operation a scalar parameter of damage was determined using the model of metal damage accumulation during monotonic deformation. It is shown that rapid cooling leads to the formation of a structure with small intermetallic particles uniformly distributed in the matrix phase. Such a structure is characterized by enhanced mechanical properties, and computer simulation allows predicting its high wear resistance in a large-sized sliding bearing during operation. Современные пакеты прикладных программ (ANSYS, Deform, LS-Dyna) позволяют рассчитать поведение материала при предельных или аварийных режимах работы для конструкций любого размера. Однако они не имеют доста-точной базы по свойствам металлов и сплавов, поэтому для адекватного описания процесса необходимо вводить экспериментальные механические свойства исследуемого материала. Цель работы -получить механические свой-ства баббита Б83 с различным структурным состоянием, для использования при компьютерном моделировании в среде программного продукта DEFORM. В качестве объекта исследования выбран баббит Б83 химического состава Cu -5,5 -6,5 % вес., Sb -10 -12 %, Sn -ост. с двумя различными структурными состояниями, полученными при раз-ной скорости кристаллизации в результате литья в форму с охлаждением на воздухе и при литье в форму с охла-ждением проточной водой (скоростное охлаждение). Механические свойства определяли при испытаниях на осад-ку согласно ГОСТ 8817 -82. Оптическую металлографию проводили на микроскопе «Axiovert-100А», с программой обработки изображения KSLite. С помощью пакета прикладных программ DEFORM-2D было проведено компью-терное моделирование работы крупногабаритного подшипника скольжения в двумерной постановке. Для оценки степени разрушения подшипника определяли скалярный ...

Pressure welding (PW) is an advanced method for obtaining solid phase joints (SPJs). Using physical and finite element modelling (FEM) it is shown that PW under superplasticity conditions provides SPJs between dissimilar cast single-crystal intermetallic and deformed polycrystalline heat-resistant Ni-based superalloys. Special attention is paid to exclude the stagnant zones in the solid phase joining region using surface relief. The results of physical modelling and FEM are in qualitative agreement. It is revealed that the surface relief can decrease the stagnant zone and increase localisation of deformation in the joining region, which helps to improve the joining quality. A monotonous change in microhardness in the joint zone is shown.

Институт проблем сверхпластичности металлов РАН, ул. Хатурина 39, 450001, Уфа Приведены данные сравнительного анализа результатов физического и компьютерного моделирования процесса сварки давлением крупнозернистого жаропрочного никелевого сплава ХН58МБЮД через ультрамелкозернистую прокладку. По результатам численного моделирования напряженного деформированного состояния показано, что значения деформаций достигают своих максимальных значений в периферийной зоне твердофазного соединения (ТФС). В этой зоне, в ультрамелкозернистой прослойке развивается локализованная низкотемпературная (850 о С) сверхпластическая деформация, что способствует образованию качественного ТФС. Проведен анализ влияния тол-щины прослойки на однородность распределения напряжений и деформаций в зоне ТФС.Ключевые слова: сварка давлением, жаропрочный никелевый сплав, крупнозернистый сплав, ультрамелкозернистая проклад-ка, метод конечных элементов. Comparative analysis of the results of physical and computer modeling of pressure welding of coarse-grained HN58MBYUD heat-resistant nickel alloy using ultrafine-grained gasket is presented. According to the results of numerical simulation of the stress strain state, maximal values of strain are observed in the periphery of the solid phase bonding (SPB) zone. In this zone, ultrafine-grained interlayer undergoes low-temperature (850°C) localized superplastic deformation, which promotes the formation of a high-quality SPB. The effect of the gasket thickness on the uniformity of stress and strain distributions in the SPB zone is analyzed. Modeling of heat-resistant nickel

Studies on the process of multiple isothermal forging of high-temperature nickel-based EK61 superalloy using computer simulation in the DEFORM-3D software package in a three-dimensional formulation and a comparison with experimental data were carried out. Based on the simulation results, it is shown that with each subsequent stage of forging, the maximum strain values become higher, and the strain differences in the central and peripheral regions become smaller. Such a strain distribution leads to the formation of a homogeneous ultrafine-grained (UFG) microstructure. The initial coarsegrained microstructure is gradually transformed into a fine-grained microduplex type microstructure at 0.77T melt and with a further decrease in the processing temperature to 0.73T melt , it is transformed into a submicroduplex type (γ + δ) UFG microstructure.

In this paper, computer simulation of the friction stir welding (FSW) of AlMg6Mn0.6 aluminum alloy sheet blanks by means of the DEFORM-3D software package is carried out to select the optimum pin geometry based on the calculation of the displacement and speed of displacement of the material points. Pins in the shape of a cylinder and a truncated cone with the cone angles of α =10, 20, and 30° were considered. The friction coefficient of 0.5 was assumed. Instrumental steel AISI-D2 was chosen as the material for the tool. To reduce the computation time and avoid the instability of solution, the model of welded blanks was built as a single body of 3 mm thickness and 40 and 30 mm length and width, respectively. The behavior of the AlMg6Mn0.6 alloy was described using the Johnson-Cook model. The FSW process was simulated at the tool moving speed v = 2 mm / s, rotation frequency ω =1000 rpm and axial force P = 25 kN. The initial temperature of the workpiece and the tool was 20°C. When welding the blanks, the conditions of heat exchange with the environment were set. The simulation results solution have shown that the flow of the material of the workpiece depends on the shape of the pin and is different over the thickness of the workpiece. The material in the lower area of the workpiece is practically not subjected to mixing for all values of the cone angle of the pin, in contrast to the middle and upper areas of the workpiece, where the material is noticeably mixed. Of all the tips considered, the most preferred for the FSW is a pin in the form of a truncated cone with the cone angle of 10°, since it provides good mixing in the plane of the workpiece, the maximum displacement of the material towards the root of the weld, and also allows one to get the most symmetrical seam.

The superplastic forming process of the VT6 titanium alloy three‐layered hollow structures with goffered filler are investigated. Based on the results of experimental studies and on the results of finite element modeling, we determine rational parameters of the process such as gas pressure increase rate, when superplastic flow condition is satisfied for ribs, and the processing time is minimal.