Technical report

No.12 Special Issue on “Steel Pipes and Tubes” and “Stainless Steel”

Development of Ultra-High Strength Linepipes with Dual-Phase Microstructure for High Strain Application


ISHIKAWA Nobuyuki     SHIKANAI Nobuo     KONDO Joe

Abstract

Extensive studies have been conducted to develop high strength linepipes with higher deformability. One of the key technologies for improving deformability is dual-phase microstructural control. Steel plate with ferrite-bainite microstructure can be obtained by applying thermo-mechanical controlled processing (TMCP), a process of controlled rolling and accelerated cooling. Low carbon, boron-free steels were used to enable the ferrite formation during cooling after controlled rolling, and accelerated cooling with an ultimate cooling rate enhanced the strength up to the X120 grade. HOP® (Heat-treatment On-line Process) was also applied after accelerated cooling in order to improve the Charpy energy of the base material. Trial production of X120 high deformability linepipe was conducted by applying dual-phase microstructural control. Microstructural and mechanical properties of X120 linepipe are introduced in this paper.

Full Pages

To view this document you need the Adobe Reader,
available for free at the Adobe Web Site.