Research On Vacuum Electron-Beam Welding Technology For A Certain Type Of Flap Slide Rail

The flap slide rail is an indispensable part of the aircraft,which is one of the most important devices in the take-off and landing of the aircraft.The steel 30CrMnSiNi2 A is widely used in the flaps slide rail structure of military and civilian aircraft.The lightweight cover board of flap slide adopt the welding manufacture technology,its welding quality will directly affect the flap slide rail safety and the life.30CrMnSiNi2 A steel has the higher specific strength and the higher hardness,the hardenability is good,the toughness is high,the bearing capacity is excellent.Because of its poor weldability in 30CrMnSiNi2 A,cold cracking is easy to occur in the welding process,and the sensitivity to notch and hydrogen embrittlement is high,so the welding method and process are strictly required.Electron beam welding(EBW)has the advantages of good vacuum protection,small deformation and high welding precision,so it is suitable for the connection of ultra high strength steel.In this paper,the vacuum electron beam welding process of flap slide rail is studied.Firstly,the structure and weldability of the slide rail are analyzed,and the changes of the aspect ratio,tensile property and impact absorption power of the electron beam welded joints under different welding parameters are studied.The influence of electron beam welding parameters on electron beam penetration and mechanical properties of welded joints was evaluated.Secondly,the microstructure of different regions of welded joints under different welding parameters was observed and analyzed,and the changes of microstructure and grain formation were recorded.Finally,different welding processes such as TIG and electron beam welding are adopted.By contrast,the requirements of welding preparation and the effect of groove state on the welding process are confirmed.The electron beam welding test of a plane flap slide rail composed of 30CrMnSiNi2 A super high strength rigid is completed.Through the comparison of tensile strength and shock absorption power under different welding parameters,the optimum process parameters under test conditions are obtained,that is,when the beam current(Ib),welding speed(v)of accelerated voltage(U),welding is: 60 kV,74 Ma,600 mm / min,respectively.The tensile properties and impact absorption energy of welded joints are 1724 MPa and 16.25 Jrespectively.The change of electron beam welding parameters has little effect on the microstructure of the welded joints,but it will significantly affect the grain size of the welded joints.The effect of welding heat was analyzed by XRD.NiCrFe,MnSi2 and other phases are formed in the zone under welding heat,and the hardness and wear resistance of these phases are good.Therefore,under the combined action of martensite and second phase produced by the welding heat affected zone,The Vickers hardness of the heat-affected zone is obviously higher than that of the weld zone,and the hardness of the heat-affected zone can reach 550 HV.There is no obvious defect in the joint when the plane flap slide rail is welded by electron beam.The mechanical properties of the welded joints were tested.The tensile strength and impact absorption power of the welded joints were 1698 MPa and 24 J respectively.The tensile properties of the welded joints were higher than the tensile strength of the base metal,which satisfied the flaps of the aircraft.Performance of slide rail components.