To impart improved corrosion resistance to crevice corrosion, when forming a lubricating coating film on a plating layer, in addition to excellent leakage resistance and seizure resistance, in a screw joint for a steel pipe composed of a pin and a box having a contact surface 30 having a screw part and a screwless metallic contact part.
The first plating layer 34 composed of a Cu-Zn alloy or a Cu-Zn-M1 alloy (M1 is one kind or two or more kinds selected from Sn, Bi and In), is formed on at least one contact surface of the pin and the box. One or both of an Ni plating layer 32a and/or a Cu plating layer 32b are formed in a lower layer of the first plating layer 34. A plating layer 36 of an Sn-M2 alloy (M2 is one kind or two or more kinds of elements selected from Bi, In, Ni, Zn and Cu), may be formed in an upper layer. A solid lubricating coating film 38a, a viscous liquid or a semi-solid lubricating coating film 38b, can be formed on the plating layer for enhancing the seizure resistance.
KANSAI KIKA KOGYO KK