Application of thermoplastic hardening for restoration of fatigue durability of gas turbine disks

The main concern of the paper is the research of expediency of applying the method of thermoplastic hardening to restore the performance of the essential parts of gas turbine engines with expired service life. For this purpose at the first stage the known repair technologies the main objective of which was to increase the operability of parts by restoring the mechanical characteristics of their material are analyzed. It was found that the technologies applied do not make it possible to achieve the goal due to the formation of tensile residual stresses in the surface layer of the part as well as the distortion of the structure of the material the part is made of and, as a consequence, the reduction of its mechanical characteristics. The method of thermoplastic hardening makes it possible to create favorable tensile residual stresses while maintaining the initial structure of the material. The fatigue tests carried out confirmed the efficiency of applying the method of thermoplastic hardening at the final stage of technology of restoring the part’s performance. It is shown that the difference of the endurance limits of new parts and those restored according to the proposed technology of repair using the method of thermoplastic hardening is 5%.