| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a carbon steel and a method for manufacturing a thick-walled pipe (wall thickness greater than or equal to about 35 mm) therefrom. <P>SOLUTION: In one embodiment, a steel composition is processed that yields an average prior austenite grain size greater than about 15 or 20 μm and smaller than about 100 μm. Based upon this composition, a quenching sequence is determined that provides a microstructure of greater than or equal to about 50 vol.% martensite and less than or equal to about 50 vol.% lower bainite, without substantial formation of ferrite, upper bainite, or granular bainite. After quenching, the pipe may be subjected to tempering. The yield strength of the quenched and tempered pipes may be greater than about 450 MPa or 485 MPa and mechanical property measurements find the quenched and tempered pipes suitable for 450 MPa grade and 485 MPa grade, and resistance to sulfide stress corrosion cracking. <P>COPYRIGHT: (C)2013,JPO&INPIT |
