| 摘要 |
PROBLEM TO BE SOLVED: To suppress a deterioration in visual quality of an electric resistance welded tube and the occurrence of defective products due to roll marks by suppressing the occurrence of the roll marks in the vicinity of the welded portion of the electric resistance welded tube which is made by hot-tube-making. SOLUTION: By using squeeze rolls 5a, 5b for butt welding of the electric resistance welded tube, the squeeze rolls 5a, 5b being provided with a composite coating film of stellite-NbC of 1-6 mm thick which is formed by plasma powder overlay and contains NbC of 20-60μm in the grain size at the volume ratio of 20-50% and is formed on the surface of at least flange parts 6a, 6b of the squeeze rolls, an open pipe 3 is welded and the electric resistance welded tube 2 is manufactured. COPYRIGHT: (C)2009,JPO&INPIT
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