Abstract
The manufacturing conditions of commercially pure titanium seamless pipes by inclined rolling process were investigated on laboratory scale. Elevated temperature torsion test was carried out to alpha forged and beta forged billets. Piercing condition was determined by a model piercing mill. A part of pierced shell was hot rolled and annealed to investigate the possibilities to attain equiaxed structure in the products.
The results were summarized as follows.
(1)Piercing operation above 1223K is recommendable to avoid low piercing efficiency of the commercially pure titanium, while the material possesses sufficient deformability in beta phase region.
(2)Equiaxed structure is obtainable by the piercing operation in beta phase region, followed by rolling in alpha phase region and annealing at 1023K. Piercing operation below 1373K is necessary to achieve equiaxed structure.
(3)Fine grain alpha forged material possesses superior deformability at elevated temperature to coarse grain beta forged material. However, the beta forged material possesses sufficient deformability for the piercing operation in beta phase region.
