Effect Of Heat Treatment On Microstructur And Mechanical Properties Of M11Nickel-based Casting Superalloy

Nickel-based superalloy plays an important role in the field of superalloymaterials. And as its merits, such as high working temperature is, good structurestability and high resistance of oxidation and corrosion, the nickel-basedsuperalloy is being widely used in the Manufacture of aviation jet engines, thehottest parts of variety of industrial gas turbine and so on. The main strengthenphase of nickel-base superalloys are Ni3(Al, Ti, Nb) intermetallic compound(γ′phase) and carbides, the strengthen phase with appropriate morphology,quantity, size and distribution can make alloys with good over-all properties.In the present study, M11nicked-based superalloy was chosen as object ofmaterial, the effect of heat treatment on γ′phase, grain boundary carbide phase,eutectic phase, grain boundary element distribution and stress-rupture propertyhave been systematically investigated by using metallographic microscope (OM),scanning electron microscope (SEM), electron probe microanalyzer (EPM). Theprimary coverage is as follows:With the solution heat treatment temperature rising, the size of γ′phasedeceases, the quantity increase, the distribution is uniform and the morphologyinto a cube shape; with the intermediate heat treatment rising, the size andquantity of γ′phase deceases, the morphology and distribution has little change;with the aging heat treatment temperature rising, the size and quantity of γ′phase increases, the morphology and distribution has little change.The carbide of grain boundary after heat treatment was analysised: with theaging heat treatment temperature rising, the size of Cr23C6carbide of grainboundary increases, the quantity increases and then decreases, the morphology isdiscontinuous chain; the size and quantity of Cr23C6carbide of grain boundary ofthe alloy after solution heat treatment compare to the alloy without solution heattreatment is larger and its morphology is continuous chain.The (γ+γ′) eutectic after heat treatment was analysised:(γ+γ′) eutectic isdifficult to dissolve when the solution temperature below1210℃and (γ+γ′)eutectic is quick to dissolve when the solution temperature above1210℃.The C element segregation after heat treatment was analysised throughelectron probe microanalyzer shows that: C element segregation in the grainboundary can be reduced by heat treatment.The stress-rupture experiment under870℃/370MPa shows that: stress- rupture life of alloy after solution heat treatment compare to the cast alloy haslittle change.