Rational approaches to high temperature induction heating

Taking advantage of the developed earlier approach to the modeling of thermo-mechanical processes in electro-conductive solids subjected to high temperature induction heating the investigation were carried out to study the effect of electric current frequency on residual stresses in a cylinder. The process of induction treatment includes heating a solid to certain temperature followed by cooling. The effect of cooling conditions on residual stresses is also investigated. It is shown that appropriate selection of cooling conditions and electric current frequency could essentially affect both a level and special features of residual stresses distributions in the cylinder. In doing so, a range of stresses spreads from compressing to tensile neighboring plasticity region. Such selection thus allows for development of rational approaches to inductive heating whose goal could be desired level of residual stresses or minimized duration of induction heating (with the desired level of residual stresses). It is shown that the model, in which the heat exchange coefficients are substituted by their averaged values over cooling interval, might lead to incorrect prediction of residual stresses in the cylinder. Specifically, the difference in values of axial residual stresses calculated using averaged heat exchange coefficients and using their real (varied with the temperature) values may be as high as 40%.