Plasma deposition dieless manufacturing of turbine parts:thermal stress control and process optimization

Plasma deposition dieless manufacturing (PDM)is a rapid heating and solidification process, in which how to avoid cracks and distortions is a key problem.Therefore, a full understanding on the evolution of temperature field variables is essential to achieve a steady state and robust PDM process.To explore the thermal behaviors of this process, the preheated and water-cooled programs for the fabrication of superalloy turbine parts have been designed respectively.Their temperature fields are then evaluated numerically by finite element method.Analysis results show that the water-cooled scheme exhibits lower hot crackability and better formability, which coincides well with experimental results.The stress distributions are further analyzed with the optimized scanning path based on the water-cooled scheme above.Computational results indicate that reasonable process-cooled conditions can reduce peak stresses and the temperature and stress gradients, and also demonstrate the feasibility and validity of this approach.More importantly, thewatercooled scheme can be easily implemented and remarkably improves the possibly-intended formability of the PDM.