Microstructure And Mechanical Properties Of Axial Friction Welded Nickel-based Superalloy GH4169

Nickel-based superalloy GH4169 is widely used in compressor disk,turbine disk,engine crankcast,compressor blades and fasteners on the hot side parts located in aircraft engine because of its high strength,high ductility,good oxidation resistance,thermal corrosion resistance,excellent fracture toughness and fatigue resistance at high temperature.Superior and efficient high temperature alloy welding technology is the guarantee of accuracy,performance and reliability.Friction welding is a kind of superior,efficient and environmental friendly solid-phase welding technology at the unique advantages of less control parameters,low heat input,little distortion and high precision,especially used in high-temperature material welding,and has been successfully applied in a variety of hot-end components manufacturing of advanced commercial aircraft engines overseas.This paper studied the nickel-based superalloy GH4169 axial friction welding process,and obtained the optimal welding process parameters in the test range:friction pressure P1=100MPa,friction time t1=10s,rotated speed n=2200rpm,upsetting pressure P2=200MPa and upsetting time t2=10s.Room temperature tensile strength and high temperature(650 ?)tensile strength of the optimal joint were investigated.According to the results of experiment,at the room temperature,the tensile strength of sample is 800 MPa,with the elongation is 60%,reduction of area is 69.75%.At the high temperature,the tensile strength of sample is 649.6 MPa,with the elongation is 60%,reduction of area is 41.2%.Both of them failed at the parent metal.Microstructure analysis of joint can be obtained,with the increase of friction pressure,the welding joint deformation zone morphology transfers from ellipse to "B"shape,and finally into a dumbbell morphology.While with the increase of friction time,the welding joint deformation zone morphology don't have a big change.Joint with superfine crystal zone,fine crystal zone and heat affected zone after friction welding,all of these areas observed(Nb,Ti)(C,N)compounds which originally exist in the parent metal.Besides,part of(Nb,Ti)(C,N)compounds broken and oxidation occurred in the superfine crystal zone.In the process of welding,with the increasing of friction pressure and friction time,heat input is increased,deformed zone width is increased,too.The deformed zone finally evolves into the fine grain zone and the heat affected zone in the centre of sample,and the super fine zone,the fine grain zone and the heat affected zone in the edge of sample.As the friction pressure increases,the area width of the non-interface is increased,the grain size decreased.As the friction time increases,the width of each area of the center of sample is increased,grain size increased.As the friction time increases,the width of the super fine zone decreased,the width of the fine grain zone decreased,the fine grain size decreased,the width of the heat affected zone increased,and the grain size decreased.When the heat input is large,heat affected zone in the center of weld seam forms y/Laves eutectic phase along the grain boundary in the process of GH4169 friction welding.We believe constitutional liquation happened in heat affected zone under the condition of large heat input.Particularly,we think y/Laves eutectic phase was generated by means of divorced eutectic reaction.