Avtomaticheskaya Svarka (Automatic Welding), #8, 2016, pp. 15-20
Improvement of crack resistance of banded supporting rolls at high-speed surfacing with low heat input
Priazovsky State Technical University, 7 Universitetskaya Str., 87500, Mariupol, Ukraine. E-mail: schetininSergey2012@yandex.ua
Improvement of crack resistance of banded supporting rolls is an urgent problem. The work is a study of the mechanism of improvement of deposited metal crack resistance with the aim of development of the process of high-speed surfacing of supporting rolls with low heat input. The method of X-ray structural analysis in diffractometer DRON-3 revealed that the electrode shape and heat input at surfacing have a considerable influence on microdistortions of crystalline lattice, which are responsible for microstresses. The latter lead to intensive formation and propagation of cracks, their initiation mechanism being associated with dislocations. Established regularities were confirmed at measurement of dislocation density by broadening of X-ray lines. Minimum crystalline lattice microdistortions, microstresses and dislocation density are achieved in surfacing with wire and composite electrode at a high speed and with minimum heat input. At increase of surfacing speed and lowering of heat input the rate of heating, cooling and solidification of liquid metal in the weld pool becomes higher, that provides microstructure refinement and increase of deposited metal crack resistance. A process of high-speed surfacing of banded supporting rolls with low heat input was proposed, providing an increase of crack resistance and preventing band failure. 13 Ref., 1 Table, 6 Figures.
high-speed surfacing with low heat input, crystalline lattice microdistortions, microstresses, dislocation density, welding stresses, crack resistance, banded supporting rolls
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