| 摘要 |
A multi-walled steel pipe comprises a metal strip plated with copper and including a brazing layer thereon. At least one surface of the metal strip is roughened and braze welded to the other, overlapping surface when the metal strip is rolled. The roughened surface has a roughness in the range of between 10 and 30 mu m. A method of making a multi-walled steel pipe comprises roughening at least one surface of a metal strip, the metal strip being previously plated with copper and including a brazing layer thereon, rolling the metal strip a plurality of times by a pipe forming machine to provide a pipe body with the roughened surface directed toward the other overlapping surface, while the metal strip being fed between a plurality of sets of rollers in the pipe forming machine, and heating the pipe body to a melting temperature of the brazing layer in a furnace so as to braze weld the overlapping surfaces of the metal strip together. |
