Study On Hot Deformation Behavior And Solid Solution Strengthening Of GH901 Alloy

Alloy GH901 is an austenitic aging hardening alloy based on Fe-43Ni-12Cr with aluminum,titanium and other elements added.At present,it is mainly used in the manufacture of aircraft turbine engines working under 650?C.Due to its poor service environment,its performance requirements are very strict.In the process of hot processing,such as forging,the alloy is easy to have cracks and defects such as coarse crystal in the structure,which affects the performance of the alloy.Therefore,it is an urgent problem to obtain the influence of thermal deformation behavior and heat treatment process parameters on grain structure.In this paper,the thermal deformation behavior of GH901 high temperature nickel-based alloy at the deformation temperature of 990?C-1140?C,the strain rate of0.001s^-1-s^-1,and the deformation amount of 50%were studied by Thermecmastor thermal simulation machine.DEFORM finite element simulation software was used to simulate the isothermal forging process of GH901 disc.On this basis,the solid solution and other heat treatment processes were carried out to analyze the evolution of microstructure under various conditions.The main research results are as follows:?1?The rheological stress curve of GH901 alloy shows that with the increase of deformation temperature T and the decrease of strain rate,the rheological stress decreases obviously.The rheological stress constitutive model of GH901 alloy under strain 0.3 and the rheological stress constitutive model considering strain compensation were obtained.?2?Based on the dynamic material model,the thermal processing map is established and the reasonable thermal processing range is obtained.DEFORM finite element analysis results show that if the plate GH901 adopts isothermal forging process,when the forging temperature is 1090?C and the deformation amount is 50%,the strain rate of the part with large bearing capacity of the forging conforms to the reasonable range of thermal processing determined by the thermal processing map.?3?The results of observation on the microstructure of GH901 alloy treated by solid solution after thermal deformation show that with the increase of solid solution temperature,the average grain size of the alloy grows gradually,and the hardness value shows a decreasing trend.The microstructure of GH901 alloy under different solid solution treatment and aging treatment showed that the average grain size of the alloy did not change significantly,and the hardness value did not change significantly.The massive rich Mo phase appeared in the grain,and carbides of various forms were precipitated in and around the grain boundary.Under the conditions of strain rate 0.03s^-1,solid solution temperature 1090?C and solid solution holding time 2 hours,the carbide distribution on the grain boundary was discontinuous,which could reduce stress concentration.