|
Vol.44, No.4, 223 ~ 234, 2006
|
| Title |
| Effects of Mo and V on Tensile and Charpy Impact Properties of API X70 Linepipe steels |
| 김영민 Young Min Kim , 신상용 Sang Yong Shin , 이학철 Hak Cheol Lee , 황병철 Byoung Chul Hwang , 박병규 Byung Gyu Park , 이성학 Sung Hak Lee , 김낙준 Nack J. Kim |
|
|
|
| Abstract |
| This study is concerned with the effects of V and Mo on tensile and Charpy impact properties of API X70 linepipe steels. Twelve kinds of steel specimens were fabricated by varying V and Mo additions and hot-rolling conditions. The addition of V and Mo promoted to form acicular ferrite, bainitic ferrite, and martensite-austenite constituents, resulting in an increase in tensile strength. The results of CVN impact tests show that the microstructures composed of acicular ferrites and fine polygonal have high upper shelf energy and low energy transition temperature. According to EBSD analysis data, the effective grain size of acicular ferrite was determined by crystallographic packets composed of a few fine grains having similar orientations. Thus, the decreased ETT in the specimens with acicular ferrite structure could be explained by the decrease in the overall effective grain size due to the presence of acicular ferrite having smaller effective grain size. |
|
|
| Key Words |
| API X70 Linepipe steel, Charpy impact test, Upper shelfenergy, Energy transition temperature, Acicular ferrite |
|
|
 |
|
