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.

This research paper studies the fracture and mechanical properties of rippled graphene containing dislocation dipoles. The atomistic simulation is performed to study the deformation behavior of pristine and defective wrinkled graphene. Graphene wrinkling considerably decreases the ultimate tensile strength of graphene with and without defects but increases the fracture strain. For graphene with the dislocation dipoles, temperature increase slightly affects mechanical properties, in contrast to graphene and graphene with Stone–Wales defect. The extremely similar slopes of the stress-strain curves for graphene with the dislocation dipoles with different arms imply that the distance between dislocations in the dipole does not have noticeable effects on the elastic modulus and strength of graphene. Defects in graphene can also affect its wrinkling; for example, preventing wrinkle formation.

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.

A material plastic flow finite-element modeling during pressure welding (PW) of two-element and three-element samples was carried out for dissimilar wrought (EP975) and cast intermetallic (VKNA-type) alloys at 1125°C and 10-4 s-1 initial strain rate. The finite-element modeling was performed in a two-dimensional set-up (plane strain). In the two-element samples case, the top element was ultrafine grained EP975 and the bottom one was VKNA-25. The top and bottom elements of the three-element samples were made from VKNA-25 while the intermediate element was ultrafine-grained EP975. The geometry in the X and Y directions were 40.5 and 5 mm for the EP975 samples and 40.5 and 3 mm for the VKNA-25 samples respectively. Experiments on PW intermetallic Ni3Al alloy and heat-resistant nickel alloy EP975 with ultrafine-grained (UFG) structure were carried out. Samples were parallelepipeds of size 10x40x3 mm3 and 10x40x5 mm3 respectively. PW was carried out at 1125 ˚C. Several combinations of welded sample surfaces with flat and grooved relief were considered. The relief made on both welded surfaces was equivalent to increase of friction between them. This results in a shear deformation reduction near the contact surfaces and degrades the welding quality as compared to the flat surfaces conventional welding. Relief applied only to one of the elements being welded results in a more efficient welding process since active deformation zones are created in the central zone, where in the other samples stagnant zones are observed. There are no deformation peculiarities in PW of the three-element samples, compared to two-element sample.

The finite element method is used to analyse the special features of plastic deformation in the weld zone of dissimilar creep-resisting materials produced by pressure welding in the presence of a relief of variable depth on the welded surfaces. The experimental results show that the weld quality can be improved by selecting a larger depth of the relief away from the edges of the welded surfaces.