Metal-made seamless pipe and process for production thereof

摘要

A metal-made seamless pipe is provided, containing at least one metal selected from the group consisting of metals each having a melting point of 1,600° C. or more, and has a porosity of 0.3 to 25%. The porosity is defined as a ratio of the open pores present at the outer surface of the pipe to the total surface area of the outer surface of the pipe. The open pores do not include through-pores perforating to the inner surface of the pipe. A process for producing such a metal-made seamless pipe is also provided. The metal-made seamless pipe is low in processability but can be produced having a small thickness and a small inner diameter, having superior mechanical strength and gastightness, and can be suitably used as a sealing member of a translucent vessel of a high-pressure discharge lamp.