Finite Element Optimization And Performance Study Of Cross Rolling Perforation Process Of TiB95

With the rapid development of seamless tube manufacture technology,the requirements for equipment and process are stricter.According to material properties and the final application of the tube,it can usually be made by extrusion,welding,or cross rolling perforation.When the required tube length-diameter ratio is very high,it is necessary to use the traditional seamless tube production technology(cross rolling perforation process).The traditional seamless tube process has high investment cost and long production process,the production technology and quality management of seamless tube have been greatly improved in recent years.With the continuous application of new equipment and new technology,people have made a long progress in the research of cross rolling.Metal rolling,involving a large number of physical parameters such as pressure,velocity,flow rate and temperature,is most complicated in the process of plastic deformation and thermo-mechanical coupling.In the past cross rolling perforation process,titanium alloy seamless tube often appears stuck tail,stick titanium,rolling card and so on.These conditions greatly affect production schedules and cause economic losses.In this paper,The Ti B95 titanium alloy bar with the size of φ195mm×1450mm was taken as the research object and the microstructure of titanium alloy was observed.The mechanical properties under different technological conditions were studied by thermal simulation compression test.The constitutive equation based on hyperbolic sine function was established to provide data support for simulation calculation.Finite element software ABAQUS/CAE was used to simulate the effects of different roll speed,initial temperature and feed angle on the quality of Ti B95 titanium alloy bar perforation.The specific results are as follows:(1)The thermal radiation causes a lot of heat loss on the outer surface of tube before rolling.It is beneficial to perforate when the roll reduction rate is about 15%.The distribution of stress-strain lamellar is W-shaped.The maximum equivalent stress and maximum equivalent strain is distributed in front of the plug and the longitudinal outlet of the inner surface of the tube,respectively.The influence of roll speed,initial temperature and feed angle on forming process was studied by using control variable method.According to the finite element simulation results,the optimal parameters were determined as roll speed 60r/min,initial temperature 1000℃ and feed angle 10°.(2)Field rolling carried out with the technological scheme that the roll speed is60r/min,the tube billet initial temperature is 1000℃ and the feed angle is 10°.The microstructure of the perforated tube is typical widmannstatten structure and the microstructure of the head and tail of the pipe after hot rolling are flake alpha +equiaxed alpha + bulk alpha+ intergranular beta.The strength and toughness of the tube can meet the technical requirements after heat treatment at 700℃ ～ 800℃.(3)The field test shows that the surface quality and dimension of the tube accord with the simulation results,and the optimization results are satisfactory.This is important for guiding the setting of the process parameters of cross rolling perforation and the field production.