PURPOSE: To produce a seamless steel pipe having excellent intergranular corrosion resistance with a simple state by subjecting a stock pipe for rolling to finish rolling at a specific temp., then cooling the pipe under specific conditions at the time of producing the austenitic stainless seamless steel pipe.
CONSTITUTION: The stock pipe for finish rolling made of an austenitic stainless steel contg., by weight %, <0.08% C, <1.0% Si, <2.0% Mn, 16W26% Cr, and <0.3% N is heated to a 1050W1200%oC range. The stock pipe for finish rolling is then subjected to the finish rolling under the conditions under which the finish temp., i.e., the finished pipe temp. T(°C) on the outlet side of a mandrel mill satisfies equation II according to the working strain at the time of the finish rolling expressed by equation I when the sectional area of the stock pipe for finish rolling is designated as Ao(cm2) and the sectional area of the finished pipe as A(cm2). The pipe is in succession cooled under the conditions under which the average cooling rate V(°C/sec) satisfies V≥C3×104 (C; the carbon content expressed by weight %) in a 900W500°C region. The seamless steel pipe made of the austenitic stainless steel which has uniformly fine crystal grains and has the extremely low corrosiveness at the crystal grain boundaries is produced even if a heat treatment stage for solutionization is omitted.
Sasaki, Akishi
Takada, Isao
