| Abstract Scope |
Over the past twenty years, significant advances have been made in the field of Nb-containing steels and associated applications, among which the most successful application case was the development and application of X80 steels with low carbon and high Nb design concept in China’s Second West-East line. With the increase of deliverability of natural gas, the corresponding wall thickness and pipe diameter have continued to increased, and grain refinement effect by adding high Nb contents has been repeatedly tested, and proved the basic metallurgical design to assure the required strength and toughness, in particular heavy-gauge X80 steels. In this paper, industrial trial results of heavy-gauge X80 steels with high Nb design have been presented and discussed, including ф1422×21.4mm SSAW pipe, ф1422×38.5mm LSAW pipe, as well as ф1219×33.0mm LSAW pipe based on strain design. |