| 摘要 |
A threaded joint has a solid coating (30) formed on a surface of a male threaded portion (11) thereof, the solid coating having fluidity during application and being cured after the application. In a made-up state, clearances are provided between flat crests (12) of the male threaded portion (11) and flat roots of a female threaded portion which face each other. The crests (12) of the male threaded portion (11) have a helical groove (40) previously formed therein, the helical groove having a lead angle equal to the lead angle of the threads. The groove (40) has a maximum depth of at least 30 µm, the depth being at most one-fifth of a height of the threads. In this threaded joint, the occurrences of galling and an abnormal make-up torque can be prevented during make-up without compromising the strength properties of the threaded joint. |
