Effect Of Stress Removing Annealing On Residual Stress,Microstructure And Properties Of Strongly Rotated Tin Bronze Cylindrical Parts

Power spinning,as a very representative near-net forming technology,is often used for processing sliding bearings because of its advantages in high material utilization,low production costs and enhanced material properties.However,for the strong spinning,because the plastic deformation is not uniform,there is a large residual stress in the spinning cylinder,and these residual stresses are bound to adversely affect the accuracy and performance of the bearing.In this paper,the microstructure and properties of tin-bronze alloy under the condition of raw bar material and hot extrusion were studied,There are coarse grains in the original bar alloy structure.After hot extrusion,the grains become smaller and more uniformly distributed.And it have many twins.The nature of the cylindrical part after hot extrusion are slightly better than that of the original bar.There are enhancements.It then carries out a strong spinning test and passes through an X-ray Residual stress of cylindrical parts after spinning was measured by diffractometer.Many residual stress left on the barrel when power spinning,and the axial direction is compressive stress,the head and tail are big and the middle is small,the shear upward is the tensile stress,it’s big in the middle and small in the head and small in the tail.After spinning,the yield tensile strength of the cylinder increases and the elongation decreases.Finally,a stress-relieving annealing test is carried out to analyze the elimination of residual stress of the cylindrical part under different annealing parameters,and to explain its elimination mechanism from the microstructure.By comprehensively considering the performance in each state,reasonable stress-relieving annealing parameters are obtained.It is very obvious for elimination of residual stress of stress free annealing process.And the axial direction is compressive stress,the shear upward is the tensile stress.When the annealing temperature is 280℃ and the holding time is 2h,axis up by 95%,tangential reduced by 89% when it compared to the spin state.And while weakening the residual stress,the nature of the cylindrical part under this annealing parameter can still be guaranteed to a higher level,so a reasonable stress-relieving annealing parameter can be obtained: annealing temperature 280℃,holding time 2h.