The paper deals with the problem of the torque in the cantilever beam with annular cross section in the elasto-plastic domain, considering the material with elastic-linear hardening model. The cantilever beam is subjected to the alternating load of such frequency that the heat is generated in the beam. The quantity of the generated heat depends on the amplitude of the torque, frequency of the load and mechanical properties of the beam material. Equations which relate the value of the torque to the extent of the plastic region of the cross section and the shearing stresses of the beam in the elasto-plastic domain are given. Furthermore, equations for deformation work, transformation work, energy due to residual stresses and energy transformed into heat are presented. The article compares results concerning the temperature change at characteristic points along the beam, obtained via numerical analysis as well as experimentally.