Development of scientific bases and optimization of technological modes of a new method of drawing cast ingots
DOI:
https://doi.org/10.14529/met160214Keywords:
cast structure, alternating deformation, dispersion of structure, mathematical modeling, stressed and strained state, stressed state parameters, degree of shear strainAbstract
The paper considers an idea of realization of alternating deformation in forging cast ingots and determines a rational shape of forging tools. The results of the analysis of the strained state of metal during compression in heads with a profiled surface and in smooth heads (at the second stage of deformation) are presented. The use of new tools provides the formation the metal structure in first passes by means of additional alternating deformation without a significant change of the cross-section shape of the billet. Alternating deformation increases the accumulated strain without changing the cross-section shape of the billet, stimulates the formation of the polygonized subgranular structure and refines the grain structure. Results of the strained state analysis of metal during forging in profiled and flat heads are presented. The degree of the accumulated strain in particles in the deformation zone is calculated for six points along the height of the section of the head hollow in order to estimate strain inhomogeneity in the ingot height. The accumulated strain for a specific particle is determined from the problem solution for a flat deformed state under isothermal conditions by means of Deform software. In layers adjacent to the contact zone the strain is minimal since there are areas of hindered deformation (sticking areas), the size of these areas decreases towards the depth of the metal; at the beginning of plastic deformation a free surface appears which is not under the working tool. Ways to control the technological process of forging are found for increasing homogeneity of strained state in the ingot section and stimulating the formation of the polygonized substructure during compression and the ultradisperse structure after metadynamic recrystallization during a pause.
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