METHOD FOR PRODUCING PLUG FOR PIERCING-ROLLING

摘要

This manufacturing method for a piercing plug used in a piercing mill for manufacturing a seamless steel pipe includes a shot blasting step wherein shot blasting is applied to the plug surface and an arc spraying step wherein a thermal spraying wire is arc-sprayed onto the surface of base material of the shot-blasted plug in order to form a coating thereon. In the arc spraying step, the arc spraying is carried out by using a cored wire (1), which is produced by filling an iron tube (2) with iron particles (4) and at least low-thermal-conductivity material particles (3) that are selected from among low-thermal-conductivity material particles (3) having lower thermal conductivity characteristics than that of iron oxide(for example, ZrO2 particles), in order to form a coating comprising iron oxide, Fe, and the low-thermal-conductivity material. Because a coating with high heat-insulating performance can be formed, a plug that allows the plug life to be improved for the piercing process can be manufactured.