Research On DD5/FGH9 Spark Plasma Diffusion Bonding Technology And Microtructure And Properties Of Joints

With the rapid development of aerospace technology,the stress and heating degree of the complex components on the aircraft increase greatly,and the problems of high temperature resistance and weight loss of the materials and components used become increasingly prominent.When making engine disc,the researchers solve the above problems from two aspects: structure and material selection.weight loss is realized by bonding blade and blade disc into integral structure instead of tenon and tenon slot connection.According to the stress distribution and functional requirements of different parts,nickel-based single crystal superalloy DD5 is selected as blade material and powder superalloy FGH98 as blade disc material.Therefore,the high quality bonding of these two materials has become one of the key to solve the problem,which is of great significance to the development of aerospace technology.The DD5 and FGH98 superalloys are bonded by spark plasma diffusion bonding.The process parameters were optimized by numerical simulation and combined with test,and the microstructure,composition and mechanical properties of the joints are analyzed.The results show that:The optimized parameters are obtained by numerical simulation via finite element software Abaqus combined with test: 925℃/14 MPa/30 min.After optimization,there are no welding defects such as unwelded and micro-hole on the interface.The temperature field of spark plasma diffusion bonding has a certain gradient,which effectively protects the base metal.Based on the thermodynamic analysis and kinetic calculation of the main elements of the joint and the results of the measured energy line scanning,the relationship between the diffusion distance of the main elements of the joint is as follows: Ti>Co>Ni>Cr.The mechanical properties of the joints showed that the joint microhardness was not less than 400 HV,and the maximum value was located on the FGH98 side at 7μm from the interface(452 HV)and the lowest hardness was on the DD5 side at 1μm from the interface(400 HV).The average tensile strength at room temperature is 1078 MPa,not less than 99% of base metal with lower performance.The average tensile strength at high temperature(650℃)is 1089 MPa,not lower than the base metal with lower performance.The creep strength of the joint σ(650℃,50 h)is 850 MPa,reaching 94.4% of the lower performance base metal.