Production and development update of X100 for strain-based design applications

摘要

The application of high-strength steels of grade 690 (X100) is of interest for very long-distance gas transmission pipelines as it promises economic benefits. Potential areas for grade 690 are arctic or seismic regions with ground movements. The technology for such regions demands a strain-based design. Low Y/T ratio, adequate uniform elongation, and the shape of the stress-strain curve are of vital importance and are nowadays at the centre of the efforts for the development of the material.rnPipes become slightly heated for application of the coating. In combination with cold deformation, which is essential in the manufacturing process, the mechanical properties specific for strain-based design application are affected. As a consequence, recent specifications include test requirements even after simulation of coating treatment.rnWithin the scope of the North Central Corridor pipeline project, Europipe manufactured 2.5kmm of grade-690 (X-100) with 42in outside diameter and 14.3mm wall thickness. The paper gives an update of the recent development status of this material for strain-based design application. The requisite properties can be obtained by appropriate design of the microstructure, in which the second phase becomes of particular importance. This calls for adequate chemical composition in combination with adapted TMCP processing parameters. The plate results are affected by the subsequent forming and aging during UOE manufacturing and application of the pipe coating. The final results under consideration from forming and ageing for this special pipe grade are described and di scussed.