PURPOSE: To obtain the titled chrome-molybdenum steel having a specified composition consisting of C, Si, Mn, Cr, Mo, V, Al, N, P, S and Fe and suitable for use as the material of a pressure vessel for a chemical plant which is operated at high temp. and pressure.
CONSTITUTION: This chrome-molybdenum steel having superior temper embrittlement resistance at its weld heat-affected zone has a composition consisting of, by weight, 0.05W0.15% C, ≤0.1% Si, 0.20W0.90% Mn, 1.00W3.50% Cr, 0.40W 1.50% Mo, 0.02W0.15% V, 0.01W0.10% Al, 0.003W0.012% N, ≤0.010% P, ≤0.015% S and the balance essentially Fe. To the composition may be added ≤0.30% Cu optionally together with ≤0.30% Ni and/or ≤0.04% Nb. Said reduced amounts of C, Si, Mn, P and S minimize temper embrittlement, and added V and Al make the structure fine.
KOSHIZUKA NORIAKI
TANAKA YASUHIRO
SATOU SHINGO
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