Papers by Keyword: Rolling

Abstract: Grain characteristics of rolled 1235 aluminum alloy were studied by EBSD. The effects of hot rolling, cold rolling and rolling deformation on grain boundaries and grain size of the metal were studied as well. The content of high-angle boundaries was low by 16.48 % in 50 % hot-rolled 1235 aluminum alloy. The complete dynamic recrystallization occurred, and grains were coarse. During 90 % hot rolling, the low-angle boundaries turned into high-angle boundaries constantly. The content of high-angle boundaries was higher by 40.16 %. Coarse grains broke into fine grains, and grew into medium grains. In the 90 % cold-rolled alloy, the trace shape of high-angle boundary was irregular. The lattice distortion was large, providing the energy needed in recrystallization during recrystallization annealing.

Abstract: Mathematical modeling of plastic deformations in rolling consists in a consequent combination of the general energetic relationship in plasticity and the variation inequality expressed the principle of minimum of entire deformation energy. A real deformation state in a plastic zone beneath rolls and corresponding kinematic and dynamics conditions on the contact surface are considered as a limited one for the consequent approximate deformation states and are found out by the method of approximated approach. Any realization of this method on personal computers requires a rational construction of a kinematic-possible velocity field in the spatial domain on plastic flow. Using the ordinary propositions and a new assumptions the authors have constructed a simple kinematic-possible velocity field in the plastic zone beneath rolls. On the base of the consequent approach in which the general energetic relationship and the variation inequality are interrelated the authors have been able to find out the geometric, kinematic and dynamics characteristics of plastic deformation’s states in metal rolling.

Abstract: Results of the comparative ductility evaluation of Ø8 rods made of copper of the KM and KMor grades are discussed. It has been found out that plastic properties of KM and KMor grade rods at room temperature practically do not differ in their specific elongation and after-fracture contraction indices. At the same time, the ductility indices of KMor rod at temperature +850 °С became, practically, half-values. Increased spread of physical property values particularly the specific ohmic resistance of the rod KMor can be explained by the cumulative effect of variations of the chemical metal composition, and changes in process variables of the process (for example, unstable density of a cast bar), that initiate an occurrence of tension stresses during rolling. Calculation data of the limiting drawing ratio μ_r demonstrated that its value must not exceed 1.475.

Abstract: The considered theoretical analysis of the roughness parameters formation of the rolling face of the pinch pass mills, when they are indented with shot, allows to obtain more adequate and convenient theoretical results for use in practice. The formation of a rough layer on the rolling working surface of the pinch pass mill is determined by the impact and penetration of the shots into its surface. When this occurs, the elastic and plastic deformation of the roll materials and shot with the dimple formation and the displacement of a portion of the deformed roll material on the edges of this dimple takes place. The obtained results allow using the mathematical dependencies to control purposefully the process of shot blasting and correct it when texturing the working rolling faces of the pinch pass mills.

Abstract: The three-layer composite AMg6–AD1–VT1-0, obtained by explosion welding, is widely used as transition elements in the creation of critical structures made of titanium and aluminum alloys. In welded joints of dissimilar metals, which are limited soluble in each other and form intermetallic compounds, mutual diffusion can occur at elevated temperatures, and when the concentration corresponding to the limit of solubility at a given temperature is reached, conditions are created for the nucleation and growth of intermetallic phases. When studying the effect of heat treatment on the properties of welded joints of such metals, it is necessary to take into account the structure, properties and features of the formation of intermetallic phases, as well as the factors that contribute to their appearance and intensive growth. The latter include hardening, obtained by the composite material after blasting and further technological operations, associated with pressure treatment, which accelerate the diffusion processes, due to fragmentation and development of the block structure.

Abstract: The paper extends Orowan’s method to the prediction of ductile fracture in plane strain rolling. In general, any uncoupled ductile fracture criterion can be used in conjunction with the solution found. However, the present paper focuses on a ductile fracture criterion based on the workability diagram. It is assumed that the initiation of fracture occurs at the axis of symmetry.

Abstract: Basing on the developed methodology for data transfer between the ProCAST and Deform-3D software products, which allows exporting geometry, temperature, residual stresses and microstructure of the casting, it is simulated semi-continuous casting of ingots from aluminum alloy 5182 into a direct chill mold and their following hot rolling in a reversing rolling stand to with aim to study microstructure the evolution.

Abstract: The paper presents the results of research of compactability processes of thermally expanded graphite powders during rolling. The thermally expanded graphite powders can be used to obtain highly porous and high-density products having different geometric parameters. The rolling method is used to produce long-length products. Strips production of the thermally expanded graphite with a particular thickness, density and physical-mechanical properties can be achieved by controlling the rolling conditions. When implementing the rolling process it is necessary to use plates due to high adhesion of powder to the rolls of the rolling mill. The usage of plates has allowed to develop the technology for the production of single and multilayer strips and evaluate its effectiveness.

Abstract: A small projection with a height and width of about 40 and 50 µm, respectively, was formed on a twin-roll-cast A356 aluminum alloy sheet by cold rolling at a rolling speed of 0.5 m/min. This projection was then used as a die to form a groove with a depth and width of about 40 and 50 µm, respectively, on a polyethylene terephthalate plate by pressing.

Abstract: One of the strategies employed to lower weight and to decrease material consumption is reducing part thickness itself. Thus, functionally graded materials in which structural reinforcement is adjusted locally, are of great interest. With regard to conventional industrial processes, such as extrusion or flexible cold rolling, thickness variations can only be achieved either longitudinally or through the cross-section of the semi-finished products. Hence, a combined thickness variation (along both axes) is difficult to generate solely by extrusion or rolling. A simultaneous thickness variation in both directions, however, would enable further weight savings in structural components such as car body parts. In this study, a promising approach with extruded shapes, serving as a billet for a flexible hot rolling process, is elaborated upon. By employing the described process modification, shapes with simultaneous thickness variations in longitudinal as well as in transverse direction are feasible. Initial numerical analysis reveals the weight-saving potential of using these semi-finished products for structural parts in a car body. A demonstration of the production process for the semi-finished parts and the occurring challenges are discussed. To verify and adjust the new technology, a numerical model of the flexible hot rolling process has been created based on the finite element software QForm VX. This model is also employed for tool design optimization to produce semi-finished components with the required geometrical quality. Finally, the results of hot rolling experiments conducted using the adjusted roll design are presented.