A Study On Thickness Reduction Technology Of Welded Tube Of Superalloy GH4169

GH4169 thin-walled tube is widely used in aerospace, aviation engine sealing device areas. The precision of dimension and mechanical properties of GH4169 thin-walled pipe is the key of corrugated pipe forming.According to the current manufacturing industry technology and equipment levels, to obtain a higher accuracy and ultra-thinner tube will not only lead a higher cost and long period of machining, but also the tube billet performance is not stable enough. It’s difficult to solve it with all of these, sohow to obtain a better performance, higher precision and lower cost of thin-walled pipe will bea difficult project. In this paper, solving this unstable problem is to simulate the parameter of process of three-roll rolling and ball spinning and solving the problem of long period of machining and high cost is to roll and spinning the tube after welding. In finial, the new process is proposed to compare with present forming project, and aim to reducing cost and shortening period of tube forming in the whole project.In this project, three-roll rolling and three dimensional elastic-plastic finite element model are both based on reality situation, the parameter of tubeis rolled from Φ62× 1.5mm to Φ45.1×0.65mm. When both doing analysis and comparing process, a better three roller rolling technology parameters with feed of 2mm/r、reduction of 15% and opening angle 14. Analysis process is to impact law in mechanical field and size of tube in three-roll rollingwhich can influenced byprocessing parameters such as the feed, the rolling speed, the groove of rolling. And compare process is by comparing the influence of different processing parameters in rolling force to get a better conclusion. At the same time, by analysis of three-roll rolling contact area, three-roll rolling regional shear stress, the distribution of rolling force, axial force and the tube deformation regularity of each stage in deformation area,the causes of the bulge in tube will be known and also an ideal process will be obtained by comparing analysis.This project is based on the actual ball spinning process in the reality working conditions, the three dimensional elastic-plastic finite element modelis established and the stress and strain distribution of steel tubes in ball spinning will be analyzed, the tube is spanned from Φ 45.1×0.65mm to Φ44.8×0.25mm.The finite simulate the finial process parameterfeed ratioislmm/rand reductionis 37.5%.Through concentrate on the stress state of contact area and studied the cause of bulge in tube, products quantity under different pressures and feed ratio on the spinning, a good understanding in flow rule of deformation and law of the tubes and stress state areas will be achieved, and it will also provide a good reference for practical production.The difference between pre-welding and post-welding in organization of tube field were observed which found that the post-welding shows a columnar dendrites performance, and also found that after four times of three-roller rolling with heat treatment, welding location of post-weldingtube are all keep invisible looking. While the micro-structure observed, shows that weld organization is not visible and transferring into an isometric organization.Then after ball spinning, the pipe becomes to the final size and the metallographic organization become tiny than before. Especially in position of weld, it will smaller than the matrix organization which means tube has been achieved better performance than no welding tubes.After welding and the ball spinning, by testing the specimen mechanical property, the tensile strength is 458.5MPa and, the grain is grade 9#, the yield strength is 985.5MPa, and contraction of area is 47.5%.Compared with no weld tube, and receive finally the wall thickness of 0.25 mm and a diameter of 70 mm which are similar to the seamless tube.