| 摘要 |
<p>A metal-sealable threaded joint for steel tube capable of being tightened and loosened repeatedly without applying liquid lubricant containing heavy metal powder thereon, comprising a pin and a box each having a contact surface containing a screw part and a screw-less metal contact part, wherein the contact surface of at least one of the pin and box is covered with a surface prepared layer and a lubrication film layer covered thereon, the surface prepared layer should desirably be a porous metallic layer of Hv 50 to 250 having a porosity of 5 to 80% and a thickness of 1 to 30 μm, and the lubrication film layer is formed of a solid lubrication film or a liquid lubrication film not containing substantially heavy metal powder, and the total of the thicknesses of the surface prepared layer and the lubrication film layer is 100 μm or less.</p> |
