| 摘要 |
PROBLEM TO BE SOLVED: To provide an austenitic stainless steel tube which has a wholly uniform, regulated, fine-grained structure where grains are not coarsened even when reheated to high temperature by welding or high temperature bending, and which maintain satisfactory oxidation resistance in moisture, and to provide a production method thereof. SOLUTION: The austenitic stainless steel tube comprises 0.03 to 0.12% C, 0.1 to 0.9% Si, 0.1 to 2% Mn, 15 to 22% Cr, 8 to 15% Ni, 0.002 to 0.05% Ti, 0.3 to 1.5% Nb, 0.0005 to 0.03% sol.Al, 0.005 to 0.2% N and 0.001 to 0.008% O (oxygen), and the balance Fe with impurities, and has a fine-grained structure having an austenite grain size number of≥7, and, preferably, having a grain mixing ratio of≤10%. The production method includes (1) a process for heating and holding at 1,100 to 1,350°C, and then cooling at a cooling rate of≥0.25°C/sec, (2) a process for plastic processing in the temperature range of≤500°C at a reduction in area of≥10%, and (3) a process for cooling after heat and holding at a temperature that is in the range of 1,050 to 1,300°C and lower than the heating temperature in the process (1) by≥10°C. COPYRIGHT: (C)2003,JPO
|
