中国微合金化技术与含铌钢发展30周-of Evolution(6)

中国微合金化技术与含铌钢发展30周-of Evolution

High Strength Microalloyed Linepipe: Half a Century of Evolution 25

Figure 5: Line pipe grade evolution

Despite the considerable amount of research on X-100 and X-120 steels since 1985 and 1998 respectively [20-32] pipes with strengths above 80 ksi have yet to see commercial service in pipelines, even though they have been incorporated into the latest revisions of International specifications [18-19]. Small quantities of X-100 linepipe have been installed in the Trans Canada System [33] to demonstrate construction feasibility, but the pipe nevertheless is operating at a relatively low stress (0.60 SMYS) relative to its real capability.

The metallurgy of X-90 to X-120 linepipe is based on very low carbon microalloyed steels, additionally alloyed with molybdenums, chromium, nickel, copper and occasionally boron, Table 2, combined with elegant TMCP cooling practices, Figures 6 & 7. Some of these concepts have been adopted in second generation X-70 and X-80 steels.