HYDROGEN-INDUCED-CRACKING-RESISTANT PRESSURE VESSEL STEEL PLATE WITH THICKNESS GREATER THAN 200-250 MM AND MANUFACTURING METHOD THEREFOR

A hydrogen-induced-cracking-resistant pressure vessel steel plate with a thickness greater than 200-250 mm. The steel plate contains the following chemical components: C: 0.10-0.20%, Si: 0.15-0.40%, Mn: 0.95-1.35%, P: ≤0.005%, S: ≤0.0008%, Cr: 0.10-0.30%, Ni: 0.25-0.40%, Mo: 0.08-0.12%, Alt: 0.02-0.05%, Nb: 0.01-0.02%, V: 0.01-0.03%, Ti: 0.01-0.02%, and B: ≤0.0005%, with the balance being Fe and inevitable impurity elements. In addition, the chemical components satisfy the carbon equivalent Ceq being less than or equal to 0.45%, and Ceq=C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15. By using high-temperature diffusion heating, high-permeability rolling and normalization + accelerated cooling with water + tempering heat treatment processes, optimal matching of the mechanical properties of a large-thickness hydrogen-induced-cracking-resistant pressure vessel steel plate is realized, and the internal quality and hydrogen-induced-cracking resistance of the steel plate are greatly improved. La présente invention concerne un plaqu