The invention provides a limit-thickness Cr-Mo ASTM A387 Gr22CL2
pressure vessel steel and a production method thereof. The Cr-Mo ASTM A387 Gr22CL2
pressure vessel steel comprises the following chemical components in percentage by
mass: 0.08-0.16 wt% of C, 0.20-0.50 wt% of Si, 0.30-0.60 wt% of Mn, at most 0.015 wt% of P, at most 0.005 wt% of S, 0.020-0.060 wt% of Als, 2.0-2.5 wt% of Cr, 0.9-1.1 wt% of Mo and the balance of Fe and residual element. The production method comprises the following steps: pretreatment of high-quality molten iron and KR molten iron, 120t top / bottom blown converter,
argon blowing by Ar
station, LF (
ladle furnace) refining, VD (vacuum
degasser) vacuum degassing, water-cooled
die casting, dead soaking pit heating, 3800mm
rolling mill, ACC
laminar cooling, straightening, cooling in
pile, heat treatment, finishing, outer inspection, flaw detection and warehousing. The steel plate is cast by a 48t water-cooled
ingot die, so the cooling and solidifying time is shortened by 1 / 3 as compared with the conventional
foundry ingot die, the defect of severe loosening or segregation at the center of the steel
ingot is reduced or avoided, and the
internal quality of the steel plate is improved.