Effect Of Heat Treatment On Microstructure And Corrosion Resistance Of GH4169 Fabricated By Selective Laser Melting

GH4169 is a nickel-based superalloy that has good mechanical properties and corrosion resistance in a wide temperature range.It is widely used in aerospace,gas turbine blades,oil and gas exploration,and nuclear engineering.However,GH4169 parts's complex shapes,high dimensional accuracy,and some even have an internal cavity structure,which brings difficult to traditional processing methods.The emergence of additive manufacturing technology can effectively solve these problems of forming and machining GH4169 parts,and speed up product development progress and reduce costs.In this paper,the GH4169 superalloy prepared by selective laser melting technology is used as test material to study the effect of heat treatment on the microstructure and corrosion resistance.Based on above research,the following conclusions were draw(1)The as-deposited state of GH4169 prepared by selective laser melting technology has an anisotropic on the electrochemical corrosion resistance.After standard heat treatment,the original anisotropy of corrosion resistance still exists.Standard heat treatment can dissolve a large amount of Nb-rich Laves phase,but has no effect on the high density dendrite structure(2)Solution heat treatment can effectively eliminate the micro-segregation of the melt pool structure and dissolved Laves phase of GH4169 prepared by selective laser melting technology.The corrosion resistance of solution state GH4169 prepared by selective laser melting technology is slightly improved compared to the deposited state,but due to the lack of strengthening phase precipitation,its hardness value(260HV)is only equivalent to the hardness value of the sample after direct aging heat treatment(420HV)60%of the hardness.(3)The solution temperature will affect the morphology of the ?phase precipitation.When the solution is at 950?,the 8 phase precipitated in a needle-shape;when it is at 1050?,the ? phase precipitated in a dot-shaped.In the single-stage aging heat treatment,prolonging the aging time can promote the apparent coarsening of the?"/?' phase.It was observed in the experiment that the size of the ?"/?'phase precipitated at 750? for 8 hours was only about half the size of the strengthened phase precipitated at 750 ? for 16 hours.