Patent ID: 11891675
Assignee: JFE STEEL CORPORATION
Field: Materials, metallurgy (Chemistry)
Classification: CPC B  C | IPC B  C

Claim 0:
1. A duplex stainless clad steel plate in which a duplex stainless steel plate as a cladding metal is bonded or joined to one or both surfaces of a base steel plate, wherein
the base steel plate comprises a first chemical composition containing, in mass %, C: 0.06% to 0.25%, Si: 0.05% to 0.50%, Mn: 0.70% to 1.60%, P: 0.030% or less, S: 0.010% or less, Al: 0.005% to 0.100%, Mo: 0.01% to 0.15%, Nb: 0.010% to 0.040%, Ti: less than 0.005%, and N: 0.0010% to 0.0100%, optionally at least one selected from the group consisting of Cu: 0.50% or less, Ni: 0.50% or less, Cr: 0.40% or less, and V: 0.050% or less, with the balance being Fe and inevitable impurities, in a range such that Nb/N is 3.0 or more and Ceq represented by the following Expression (1) is 0.35 to 0.45:

Ceq=C+Mn/6+(Cu+Ni)/15+(Cr+Mo+V)/5  (1), where the symbol of each element indicates the content in mass % of the element, and any element not contained is calculated as 0,
the duplex stainless steel plate comprises:
a second chemical composition containing, in mass %, C: 0.030% or less, Si: 1.00% or less, Mn: 2.00% or less, P: 0.050% or less, S: 0.0100% or less, Ni: 5.00% to 8.00%, Cr: more than 24.0% and not more than 28.0%, Mo: 2.5% to 4.0%, and N: 0.08% to 0.30%, optionally at least one selected from the group consisting of Cu: 1.50% or less, W: 1.50% or less, Co: 1.50% or less, Ti: 0.25% or less, and Nb: 0.25% or less, with the balance being Fe and inevitable impurities, in a range such that PI defined by the following Expression (2) is 34.0 to 43.0:

PI=Cr+3.3Mo+16N  (2), where the symbol of each element indicates the content in mass % of the element; and
a microstructure containing a ferrite phase in an area fraction of 35% to 65%, and
in the microstructure, an amount of precipitated Cr is 2.00 mass % or less and an amount of precipitated Mo is 0.50 mass % or less.