POSCO Holdings Inc.
Pressure vessel steel plate having excellent post weld heat treatment resistance, and manufacturing method therefor

Abstract:

The present disclosure relates to a middle high temperature pressure vessel steel plate having excellent resistance against a post weld heat treatment (PWHT) and a manufacturing method therefor. The pressure vessel steel plate includes 0.05 to 0.17 wt % of C, 0.50 to 1.00 wt % of Si, 0.3 to 0.8 wt % of Mn, 1.0 to 1.5 wt % of Cr, 0.3 to 1.0 wt % of Mo, 0.003 to 0.30 wt % of Ni, 0.003 to 0.30 wt % of Cu, 0.005 to 0.06 wt % of Sol.Al, 0.015 wt % or less of P, and 0.020 wt % or less of S; additionally two or more elements selected from 0.002 to 0.025 wt % of Nb, 0.002 to 0.03 wt % of V, and 0.002 to 0.15 wt % of Co; and Fe and unavoidable impurities as the reminder, wherein a microstructure of a central portion of the steel plate is formed in a mixed structure of 20 area % or more of tempered martensite and the residue bainite.