| 摘要 |
PROBLEM TO BE SOLVED: To provide an inexpensive steel pipe having satisfactory workability, and to provide a method for producing the same. SOLUTION: In a steel pipe produced by subjecting a steel pipe as a pipe stock to cold pipe drawing and thereafter heating the same in the temperature range from an Ac1 transformation point -70°C to an Ac1 transformation point, in the whole region of the steel pipe including a seam weld zone, the fraction of ferrite is controlled to≥60%, average crystal grain size is controlled to≥10μm, the average value of an aspect ratio is controlled to 1.0 to <5.0, and a specified texture is formed so as to obtain a steel pipe in which rL and rC are increased, and workability is improved. Further, In the method for producing the same, the pipe stock is subjected to cold pipe drawing so as to be a specified reduction of area and a specified reduction of thickness, is heated in the temperature range of an Ac1 transformation point -70°C to an Ac1 transformation point for 30 s, and is thereafter cooled. COPYRIGHT: (C)2009,JPO&INPIT
|
