| Abstract |
| The resistance of hydrogen induced cracking (HIC) was investigated with different microstructures of API X70MS steel. Ferrite/acicular ferrite (F/AF), deformed ferrite/acicular ferrite, ferrite/bainite (F/B) and single acicular ferrite (AF) were obtained by thermo-mechanical controlled process (TMCP) with changing rolling and cooling conditions. HIC resistance was found to be affected by the type as well as morphology of the microstructure, and thus the behavior of crack initiation and propagation could be analyzed. It was found that single AF and deformed F/AF with uniformly distributed dislocation reduced HIC initiation. Banded microstructure with a hardness value below 250 HV, such as AF, showed good HIC propagation resistance due to high toughness. AF generally exhibited excellent crack initiation and propagation resistance, namely the best HIC susceptibility performance. AF might redeem the HIC resistance for the banded microstructure also.
(Received January 24, 2017; Accepted March 7, 2017) |
|
|
| Key Words |
| linepipe steel, microstructure, hydrogen induced cracking (HIC), acicular Ferrite, banded microstructure |
|
|
 |
|
