CR-MO STEEL HAVING EXCELLENT RESISTANCE TO HYDROGEN EROSION AND SR CRACKING

摘要

PURPOSE:To improve the resistance of a Cr-Mo steel for a pressure vessel to hydrogen erosion and SR corrosion by adding a specific trace element to said steel. CONSTITUTION:The Cr-Mo steel contg., by weight %, 0.05-0.20% C, 0.4% Si, 0.1-1.0% Mn, 2.0-3.5% Cr, 0.8-1.6% Mo, 0.10-0.35% V, 0.005-0.05% Nb, 0.005-0.035% Ti, 0.08% Al, 0.0050% N, 0.010% P and 0.004% S is used as the material for various pressure vessels to be used in a high-temp. high-pressure hydrogen atmosphere. At least one kind of rare earth elements and Ca are otherwise incorporated therein at 0.001-0.03% or =1 kinds of hardenability improvement components of 0.005-0.004% B and =0.5% Cu or Ni in total are incorporated independently or in combination therein. The Cr-Mo steel having the excellent resistance to hydrogen intrusion and SR cracking (the resistance to the cracking to be generated during stress relief annealing after welding) is thus obtd.