Studies On Heat Treatment Process And Properties Of Superalloy For Brush Seal

GH4169 alloy is a precipitation hardening nickel-based deformation superalloy and widely used in aviation,navigation,chemical industry and other important fields.With the continuous development and application of GH4169 alloy,the high temperature mechanical properties,corrosion resistance and other comprehensive performance requirements of alloys have been continuously improved.In this paper,the influence of heat treatment process on microstructure and properties of the alloy is systematically studied by microscopic morphology observation,tensile test,hardness test and electrochemical analysis.The work could provide a certain guiding role for the heat treatment process of GH4169 alloy in the practical production of brush seal.It is indicated that:During the solid solution treatment,with the increase of solution temperature and the prolongation of solution time,the strengthening phase??in GH4169 alloy is gradually dissolved,and the total dissolution temperature is between 900?and 950?,The precipitates like carbide near the grain boundary or near the grain boundary will dissolve,and the grain grows with the rise of temperature.With the increase of the solid solution temperature,the strength and hardness of GH4169 alloy gradually decrease,and the plasticity increases,while the effect of the solution time is relatively small,which is in accordance with the evolution law of the microstructure of the alloy.With the increase of the solid solution temperature and the prolongation of the heat preservation time,the corrosion resistance of GH4169 alloy is improved,namely the corrosion potential is gradually increasedand the corrosion current density is gradually reduced,which indicates the corrosion of the alloy is more and more difficult,and the corrosion rate is slower and slower,especially after the solution treatment of60min at 1050?.The corrosion potential of the alloy increased by 177mV compared with that of the non-solid solution,and the corrosion current density decreased by 22.1?A·cm^-2.During the aging treatment process,with the increase of aging temperature and prolonging the time of heat preservation,the grain size of GH4169 alloy changes very little,basically remains unchanged,while the precipitated phases,such as strengthening phases and carbides,continue to precipitate,gather and grow,and the tensile strength and hardness atthe room temperature increase gradually,whilethe plasticity is reduced,and the change range is becoming smaller and smaller.This corresponds to the microstructural change of the alloy during the aging process.At the same aging time,the corrosion potential of the alloy increases first and then decreases with the aging temperature rising,and the maximum value is reached at 650?,and the variation of the impedance is basically the same.With the increase of aging temperature,the change law of corrosion current of alloy after ashort time aging treatment is not obvious,but corrosion current of alloy decreases obviously and corrosion rate decreases gradually aftera long time aging treatment.Under the same aging temperature,the corrosion potential decreases and the corrosion current density increases gradually with the aging time prolonging,and the corrosion resistance of the alloy decreases.With the extension of aging time,the impedance of the alloy increases first and then decreases after aging at a lower temperature,while the impedance decreases gradually at a higher temperature.