Numerical Analysis Of Thermal-mechanical Coupling In Inertia Friction Welding Based On 3D Friction Pair Model Of Dual Plastic Body

As one of solid state welding technologies,and compared with continuous drive friction welding(CDFW),inertial friction welding(IFW)has some advantages in improving the welding quality,joint performance and material process adaptability,which is applied to manufacturing the rotating parts of aero-engine.The in depth understandings of the thermal-mechanical coupling and its influence mechanism on the microstructure evolution is of great significance to optimize the welding process and obtain high-quality welded joints.In view of the shortcomings of the traditional research method "trial-and-error method",such as large workload and high research cost,numerical simulation technology has become an important research method in hot working field.In the past,numerical model with a rigid/plastic friction pair model was used to simplify the inertia friction welding model due to the limitation of computer processing capacity and calculation cost.To a certain extent,the simplified model can accelerate the calculation speed and reduce the calculation cost,but which ignores the thermal and mechanical interaction of two workpieces on both sides of the friction interface,and it is difficult to reflect the physical nature of IFW.Based on the 3D double plastic bodies friction pair model,IFW model was established.In the model,the welding workpieces on both sides were dealt with the elastoplastic body,and the temperature-dependent thermos-physical properties of material were considered comprehensively.Based on the hot compressive tests,the constitutive equation of welding materials at high temperature and large deformation was established,and then used to describe the flow stress in IFW.Based on the classical coulomb friction model and the friction coefficient mathematical model related to the interface state,the transient friction heat generation model is established and combined with the plastic deformation heat to describe the heat input during IFW.The Arbitrary Lagrange-Euler(ALE)method was used to study the mesh distortion caused by material deformation in the inertial friction welding process.The accuracy and reliability of the developed IFW model have been well verified by temperature measurements and deformation data.Based on the established numerical model,the thermal-mechanical coupling behaviors involving temperature field,stress and strain field and plastic flow field in IFW process of the similar/dissimilar superalloys were studied systematically.In the inertia friction welding process of GH4169 high temperature alloy,the temperature of the 2/3 radius annular region is the highest in the friction interface and can reach 1260 ?.When the flash edge begins to form,it has peak plastic deformation heat production power,which has a ratio of friction to heat production of 12.3%.The maximum plastic rheological velocity of the friction interface can reach 0.88 m/s,and the maximum flash extrusion speed is 2.5 mm/s.The metal at the friction interface less than 30%radius is difficult to extrude.After the plastic deformation of the interface metal,the stress is always in the range of 100-200 MPa,and the plastic strain is concentrated in the range of 5 mm on both sides of the interface,and the distribution characteristics of "central narrow and wide edge" are exhibited.After cooling for 50 s after welding,there is still a hoop tensile stress of about 200 MPa on the flash.In the inertia friction welding process of FGH96/GH4169 dissimilar superalloys,the peak temperature of the friction interface can reach 1300 ?.In the vicinity of the interface,FGH96 has higher temperature than GH4169.The deformation of the interface is significantly different.The axial shortening of GH4169 is 3 times that of FGH96.The plastic strain field distribution is characterized by "narrow center and wide edge",but the peak strain at the center of the interface is higher than the edge.The plastic strain on the FGH96 side is smaller than GH4169,and the strain is mainly concentrated in the range of 2.5 mm from the interface.The studies reveals the thermal coupling mechanism in IFW of superalliys,and expounds some fundamental issues involving heat generation,heat transfer and elastic-plastic behavior in details.And it also lays a foundation for the study of the microstructure evolution in IFW.It will support the development and manufacture of CJ series aero engine in theory.