METHOD FOR PRODUCING SEAMLESS PIPE

摘要

A method for producing a seamless pipe in which carburization occurring in the production process of a pipe is prevented and the stretch-rolling process is rationalized. In the process of producing a seamless pipe, a pipe bored in a boring-rolling step is rolled without using an inner surface restricting tool in the stretch-rolling step or without performing stretch-rolling, swaging-rolling is performed in a swaging-rolling step, and wall-thickness machining is performed by means of a cold-rolling machine or a cold-drawing machine in a cold-rolling step. According to the method, trapping of graphite fine particles to the inner/outer surfaces of the pipe caused in conventional stretch-rolling is reduced and carburization of pipe can be prevented. The method is especially effective as a carburization preventive measure of extremely low carbon stainless steel and high alloy steel.