Deformation Inhomogeneities in Upset Forging
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Published:1983
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Axisymmetric upsetting of cylindrical billets under isothermal and nonisothermal conditions is investigated. For isothermal cases, OFHC (oxygen-free high-conducting) copper at room temperature and titanium alloy Ti-6242 at elevated temperatures are considered. Modified stress distribution functions for a semi-empirical model of upset forging are presented. From this model, information on load-displacement and the development of deformation inhomogeneities are obtained that compare favorably with the experimental data.
For nonisothermal cases, analysis for one-dimensional, non-steady-state heat conduction is incorporated into the semiempirical model. The effect of die-chilling on dead-zone formation and the development of inhomogeneities is investigated. It is found that material and process parameters related to the heat transfer characteristic of the system (billet, dies, and the lubricant films, in this case), as well as the temperature sensitivity of the billet material, have pronounced effects in this respect.