|
Vol.42, No.9, 691 ~ 701, 2004
|
| Title |
| Analysis of Toughness and Transition Temperature of High-Toughness Pipeline Steels 1. Charpy Impact Properties and Effective Grain Sizes |
| 황병철 Byoung Chul Hwang , 김양곤 Yang Gon Kim , 이성학 Sung Hak Lee , 김영민 Young Min Kim , 김낙준 Nack J. Kim , 유장용 Jang Yong Yoo |
|
|
|
| Abstract |
| This study is concerned with the effects of microstructure on Charpy V-notch (CVN) impact properties of a high-toughness API X70 pipeline steel. Six kinds of steel specimens were fabricated by varying hot-rolling conditions, and their microstructures and CVN properties were investigated. In addition, their effective grain sizes were characterized by the electron back-scatter diffraction (EBSD) analysis. The Charpy impact test results indicated that the specimens rolled in the single phase region had the higher upper shelf energy (USE) and the lower energy transition temperature (ETT) than the specimens rolled in the two phase region because their microstructures were composed of acicular ferrites and fine polygonal ferrites. The decreased ETT in the specimens rolled in the single phase region could be explained by the decrease in the overall effective grain size due to the presence of acicular ferrite having smaller effective grain size. On the other hand, CVN properties of the specimens rolled in the two phase region were deteriorated as they contained a small amount of martensites or cementites. |
|
|
| Key Words |
| API X70 pipeline steel, Rolling condition, Charpy V-notch, CVN, impact test, Upper shelf energy, Energy transition temperature |
|
|
 |
|
