Study On Plastic Deformation And Fracture Behavior Of Nickel-Based Single Crystal Superalloy

Nickel-based single crystal superalloys have good structural stability and reliability at high temperatures,and are commonly used materials for turbine blades of aerospace engines.In order to study the calculation method of turbine engine blade fracture speed,the paper studies the plastic deformation and failure behavior of nickel-based single crystal superalloy DD416 at room temperature and 700 °C.The main work and conclusions are as follows:(1)Metallographic tests were carried out to confirm the crystal orientation of the material by observing "cross" dendrites.Specimens were processed according to the specified orientation.Quasistatic tensile tests were carried out for smooth specimens and notched specimens at room temperature and 700?.(2)Based on the tensile response test curve,a macroscopic anisotropic constitutive model at room temperature and 700? high temperature was established by means of inverse optimization.The finite element prediction analysis of tensile deformation response of notched specimens at room temperature and 700? high temperature was carried out.The results show that the constitutive model can predict the deformation behavior of single crystal specimens well before reaching the ultimate load,but it can not effectively predict the deformation behavior of single crystal specimens.After that,the deformation behavior of materials is often overpredicted.By introducing the failure criterion related to plastic work density,the predicted results of large deformation finite element method are revised to make the predicted results closer to the test values,and the predicted values of ultimate strength of notched specimens are obtained,and the predicted error of ultimate strength is controlled within 6%.(3)Based on the actual load characteristics of the aero-engine power turbine blade working speed,blade simulation Specimens that can be used in the tensile test were designed,and the large-deformation finite element analysis were applied to the tensile response using the above-mentioned macroscopic anisotropic constitutive model combined with the failure criterion.The prediction results agree well with the experimental results,and the ultimate load prediction error is less than 3%.