Formation of the joint of dissimilar metals in the solid phase by the method of vacuum hot rolling
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FORMATION OF THE JOINT OF DISSIMILAR METALS IN THE SOLID PHASE BY THE METHOD OF VACUUM HOT ROLLING B. V. Borts
UDC 621.791.011
On the basis of the experimental data and physical principles, we formulate the principal conditions of getting stable solid-phase joints of dissimilar materials as a result of their simultaneous vacuum hot rolling, namely, the possibility of sliding of one metal over the other, the motion of metals must obey the Bernoulli equation for incompressible liquids, the possibility of mass transfer of the atoms of dissimilar metals through their common boundary, the continuity of the flow or the second-by-second equality of the masses of rolled metal, and the equality of powers acquired by the metals. Keyword: joints of dissimilar materials, solid phase, regularities, rolling.
The solid-phase welding of dissimilar materials by the method of vacuum hot rolling opens new promising directions for the application of this method in the industry [1–3]. The well-known methods of connecting of dissimilar materials are based on their plastic deformation, as a rule, in a uniaxial direction. Therefore, the theory of creation of solid-state joints was developed with regard for these technologies [3, 4]. The method of vacuum hot rolling noticeably changes the theoretical concept of solid-phase joining of large massive plates made of dissimilar materials over the thickness and length. As a rule, in the process of rolling in the solid phase, they are combined in packs 50 × 100 × 400 mm in sizes. The thicknesses of the components of the packs are, e.g., 23 mm for 08Kh18N10T steel and 27 mm for titanium. If necessary, it is possible to use barrier and damping interlayers of appropriate materials (Ni, Cu, Nb, V) with thicknesses of 0.3–1.0 mm. The solid-phase welding of dissimilar materials by the method of rolling is realized as a result of plastic deformation. Note that the material with higher plasticity deforms stronger and slides over the material with lower plasticity. The process of sliding and the action of compressive forces are accompanied by the formation of friction forces, the subsurface layers are cleaned and, in the course of subsequent deformation, the materials are joined in the solid phase [5, 6]. The process of dry sliding friction between plastic solid materials is controlled by the localized plastic deformation on the microlevel [5, 6], whereas the structure on the atomic level and the composition of contacting surfaces are determining for the joining of materials in the solid phase. The relationship between the contacting solid bodies and disordering in the zone of interface on the atomic level was studied in [7–11]. However, the specific features of the processes running on the macrolevel and reflecting the principal regularities of stable rolling of the metals depending on its rate, temperature, and the thicknesses of the metals require additional comprehensive analysis. This is why the aim of the present work is to formulate the principal conditions and regularities necessary for the forma
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