LINE PIPE STEEL WITH SUPERIOR WET CARBON DIOXIDE CORROSION RESISTANCE AND WELDABILITY

摘要

PURPOSE:To provide a line pipe steel having high corrosion resistance to wet CO2, superior weldability and a weld crack sensitivity index regulated to a low value and contg. C, Si, Mn, Cr, Nb, Al, B and N each in a predetermined percentage other than the balance Fe and impurities. CONSTITUTION:This steel is composed of C=0.10%, Si 0.10-1.00%, Mn 0.10- 1.20%, Cr 1.0-3.0%, Nb 0.01-0.08%, Al 0.01-0.10%, B 0.0002-0.0050%, N 0.0010-0.015%, and the balance Fe and impurities. The ratio of B/N (content) is regulated to 0.1-0.6, and S and Cu among the impurities to S=0.010% and Cu= 0.04%. In addition, the weld crack sensitivity index PCM of this steel represented by the equation is regulated to 0.23% or less. This steel has high sulfide crack resistance as well as the above-mentioned characteristics.