| abstract |
A threaded joint for a steel tube formed on a spike and a housing that have a contact surface that includes threaded parts and a non-threaded metal contact part and that is able to stably assure excoriation resistance and a tightness to air without applying compound grease to it, where a solid lubricating film formed with lubricating powder (for example, molybdenum disulfide) and an organic or inorganic agglomerate is formed on the contact surface of at least one of the pin and the case, the ratio of the area occupied by the secondary particles of 15 to 60 (m in equivalent diameter of equal area of the lubricating powder in the effective section of the solid lubricating film in the thickness direction is 5 to 90% and the product of fiber-like filler (for example metallic filamentous growth of inorganic substance) in addition to the lubricating powder is mixed in the solid lubricating film in the mass ratio of the binder fiber filling product of 0.01 to 0.5, therefore, in particular, resistance to excoriation and high temperatures can be improved. |