Concepts of grade X100 for high toughness and strain based design application

摘要

The first studies on grade X100 were focussed on fracture propagation control. Therefore the requirements for intrinsic crack arrest were intensively studied. As a result a first-generation was developed with highest possible toughness.rnA second-generation was required for arctic or seismic regions with ground movements. The technology for such regions demands a strain-based design. Low Y/T-ratio and adequate uniform elongation are becoming of vital importance and are in the center of the efforts for the development of.rnThe demanded properties can be obtained by appropriate design of the micro structure. Especially the second phase becomes of extreme importance. This calls for adequate chemical composition in combination with adapted TMCP processing parameters. This paper illustrates the different production concepts. Mechanical properties achieved on prototype plate are presented. Microstructures will be specified and related to the properties. As the plate results are affected by the subsequent forming and aging during UOE manufacturing and pipe coating the influence of these production steps on the mechanical properties in the final delivery condition are furthermore summarized.