Electromagnetic Testing State Of Superalloy GH4169 With Heat Treatment

Superalloy GH4169 is widely used in the aerospace.Its property is determined by the structure of material.The conventional microstructure detections use metallographor electron microscopy methods which need to damage the parts orcan'tdetect in service.It is based on the relationship between propagation characteristics of eddy signal,conductivityand magnetic permeability with metallographic structure,thus the article is aimed at evaluatingsuperalloy GH4169 material heat treatment condition by using eddy signal.According to change thesolution temperature of superalloy GH4169 and the cooling method,this articleget various microstructure,we know the phase transition point and the dissolution temperature of the strengthening phase using DTA,and observe the change of microstructure by using metallographic method or electron microscopy.The characteristic parameters of metallographic structure are collected by an open platform ImageJ which is based on self-made software for metallographic analysis.The characteristic parameters include the average grain diameter,grain long axis,grain short axis and so on.This article measures the material hardness in different state organiz,measuring the conductivity of the sample with different microstructure by eddy current testing.Meanwhile,not only does it measure the magnetic of the sample surface of a fixed strength in the magnetic field,but also measures the amplitude difference of eddy current lift-off effect.The results of metallographic analysis show that when the solid treatment temperature is lower than the phase transition temperature,because the ? facies have a pinning effect on the grain boundry,the average grain diameter(26 ~ 28?m),grain long axis(30 ~ 36?m),grain short axis(20~22?m)all grow,in fact,is not obvious.When the solid treatment temperature is higher than the phase transition temperature,the growth rate of the grain diameter(50~123?m)increases significantly.With temperature increasing,the conductivity which is lower than the phase transition temperaturebecomes higher than the conductivity and the phase transition temperature.The conductivity goes down with temperature increasing.The magnetic induction perpendicular to the surface of sample with temperature increases.andthe amplitude difference of eddy current lift-off does an effect on going down with temperature increasing.These changes are corresponding to solid solution strengthening phase in the process of solubility,the solid solution atoms into the substrate and the lattice distortion increases,which lead to the decrease of the electrical conductivity,and the amplitude difference of eddy current lift-off effect decreases.Besides,the strengthening phase pinning effect is decreased for magnetic domain and make the relative permeability rise.The microstructure and material electromagnetic properties are chang,with the change of the alloy heat treatment state.The results of this paper to be used for nondestructive speculate the change of GH4169 microstrucure,Used for study on the organization evolution of GH4169 which at high temperature use for a long time in aircraft engine.To ensure the safety in use of aircraft engine.