Metallic seamless tube and process for producing thereof

摘要

The present invention relates to a metal-made seamless pipe (30) containing at least one metal having a melting point of 1,600 degC or more and being selected from the group consisting of Mo, W, Re, Ti, Hf and Zr metals. The metal-made seamless pipe has a porosity of 0.3 to 25 percent when the porosity is defined as a proportion of the open pores not perforating in the thickness direction of the pipe. Inside diameter of the pipe (30) ranges within 0.4 to 3,0ámm and thickness thereof is in the range of 0.05 to 1,0 mm. Disclosed is also a process for producing the above-described metal-made seamless pipe, which comprises: preparing a mixture containing 80 to 98 percent by weight of a powder of at least one kind of metal selected from the group consisting of Mo, W, Re, Ti, Hf and Zr metals, each having a melting point of 1,600 degC or more and a binder in a solvent, kneading the mixture for 0 to 3 hours and then extruding the kneaded material to form a pipe-shaped material (30), and drying the pipe-shaped material at -5 to 25 degC for a period of 10 to 48 hours from the completion of the extrusion and thereafter at 30 to 120 degC for a period of 0.5 to 8 hours and then firing the dried material at a lower temperature selected from a temperature between 1,000 to 2,100 degC or at a temperature being lower by 300 degC than the melting point of the metal.