Numerical Simulation And Experimental Investigation On The Neck-spinning Of GH625 Superalloy Tube

GH625 superalloy reducer tube is an important product used in plumbing system applying for aeronautical and aerospace industries.It is mainly applied in the pipe of the engine countervanes.The reducer tube is usually fabricated by the welding process,which is easy to cause deformation and crack generation during the high temperature,leading to the service life of the reducer tube decreasing.However,the multi-pass neck spinning is an advanced process for forming the GH625 superalloy reducer tube,which can achieve the integral forming and improve service life of the reducer tube.As for the multi-pass neck spinning process,the dimensional precision of the reducer tube is affected by different process parameters.Thus,it is very important to study the spinning process parameters on forming GH625 superalloy tube.Because of high temperature condition,the reducer tube requires good microstructure,mechanical properties,creep and fatigue properties.Therefore,the microstructure and property of the reducer tube also need to be explored after spinning forming.In this study,the process parameters of the multi-pass neck spinning were studied by ABAQUS software,including axial feed rate,spindle speed,roller nose radius and roller indentation.Then,the multi-pass neck spinning experiments were conducted according to the finite element simulation results.Eventually,the solution treatment of GH625 superalloy reducer tube was investigated after tube spinning.The research contents and conclusions were as follows:(1)The multi-pass neck spinning process parameters were chosen before spinning and the spinning tools were designed based on the forming theory of neck spinning.(2)The effect of the different process parameters on thickness and diameter was studied during the process of numerical simulation.The results showed that the tube thickness of the first pass increased with the process parameters increasing,such as axial feed rate,spindle speed and roller nose radius;however,the tube thickness decreased with the the process parameters increased in the last pass;the diameter growth of the first and last pass was decreased as the axial feed rate and spindle speed increased;very limited diameter growth were found in the first pass with the increase of roller nose radius,but the diameter growth increased greatly in the last pass;the larger roller indentation was adopted in the first pass with the less roller indentation in the last pass,in order to avoid the serious diameter growth and meet the thickness requirement.(3)The effect of the axial feed rate and spindle speed on internal and outer surface quality of tube was investigated by experiments.Then,the experiments of the multi-pass neck spinning were conducted to verified the accuracy of the simulation results,and the final process parameters of GH625 superalloy reducer tube were also obtained by experiments.(4)After tube spinning,the grain of the deformation region was elongated in axial direction.In transverse direction,the inside grain was thinned,but the outside grain was elongated and twisted.When the reducer tube was treated at 980 ℃,the results showed that the crystal granularity was between the 7 and 8 degree and the tensile strength was larger than 950 MPa with 45% of the elongation.