Sticking Defects and Its Influence on Shell Tube in Rotary Piercing Process of Large Diameter TA2 Titanium Tube

Aiming at the problem of the sticking defects in the rotary piercing process of large diameter TA2 titanium tube,the influence of the sticking defects on the surface condition,deformation defect,dimensional accuracy and other macro-quality of the pierced shell tube and the micro-structure distribution were analyzed.The results show that the rolling process time is extended due to the sticking defects and its treatments of the guide plate.The coating has a certain inhibition effect on the sticking defects,but it is basically failed after the single pass piercing rolling.The annealing micro-structure of the tube is equiaxed grains and the grain size is refined to a great extent after the rotary piercing process.The influence of the discs sticking defects and the process extension time on the grain size is not obvious.Therefore,the corresponding measures,e.g.control of the furnace temperature,optimization on feeding mode and adopting guide discs of cast iron,were taken to reduce the titanium sticking degree,which effectively improve the surface quality of the shell tube and reduce the loss of the discs.