Research On Arc Additive Forming Quality Of Superalloy Parts

Due to the excellent properties such as high temperature resistance,corrosion resistance and creep resistance,superalloys are widely used in industry,however the low efficiency and high cost of traditional processing methods limit its further development.In recent years,with the advantages of high efficiency and low cost of arc additive technology,superalloys have new room for development.Microstructure and properties of superalloy additive parts are the key factors affecting its application in engineering.Therefore,the forming quality of TIG arc additive for GH4169 superalloy is studied in this paper.The mathematical model of single pass cladding and multi-layer deposition of arc additive was established by scanning the contour of overlay and simplifying the weld bead model.The thermophysical parameters of the material under high temperature conditions were calculated by JmatPro software.The dynamic simulation of arc additive process was realized by using the life and death element method,with the aid of ANSYS parameterized design language APDL.The temperature field of single pass cladding was simulated and the accuracy of simulation was verified through experiment comparison.On this basis,a multi-layer deposition simulation was performed to analyze the temperature field change law and the effect of the substrate on the bead heat dissipation.The macro forming quality of nickel base superalloy could be effected by many additive process parameters.So the effects of different additive process parameters on the macro forming quality of nickel base superalloy were studied.Firstly,the range of process parameters for stable forming of nickel base superalloy during single pass cladding was explored through orthogonal experiments,and then the influence of process parameters such as welding current,welding speed and wire feeding speed on the weld bead width and residual height were explored.The mathematical model of the relationship between the additive process parameters and the bead weld width and residual height was established through the multivariate nonlinear regression analysis.In the multi-layer cladding process,the influence of additive process parameters on the forming morphology of straight wall parts was studied.The relationship between the height of each cladding layer was explored through experiments,and the problem of lifting height of the welding torch in the process of automatic additive was solved.The effects of different additive process parameters on the microstructure and mechanical properties of nickel base superalloy were investigated.Firstly,the growth characteristics and microhardness of single pass cladding were analyzed.Then the changes about the columnar crystals grain size,precipitation phase and microhardness in different place were explored during the multilayer deposition.Finally,single factor control variable method was used to clarify how microstructure,microhardness and tensile strength of the formed parts changed with the change of additive process parameters.The surface quality of the shaped part determines whether it can be practically applied.So that an integrated forming system of robotic arc additive manufacturing and CNC subtractive finishing was designed to improve the quality.Through the design of special fixtures,two sets of additive forming systems were built,namely,the machine tool arc additive forming system and the integrated forming system of robotic arm arc additive and machine tool milling material.By means of the communication function of the CNC machine M code and the external interface of the robot,the communication integration between the robot and the CNC machining,welding machine and wire feeder was realized.Then the coordinate calibration of the additive system and the subtractive system was completed.Finally,the feasibility of the system was verified by the experiment of forming straight wall blade.