Clad steel plate, member, and production methods for same

A clad steel plate having a base metal and a cladding metal on front and back surfaces of the base metal,

• the base metal comprising a chemical composition containing, by mass %,
• C:
• 0.080% or more and 0.350% or less,
• Si:
• 0.50% or more and 2.00% or less,
• Mn:
• 1.80% or more and less than 3.50%,
• P:
• 0.001% or more and 0.100% or less,
• S:
• 0.0200% or less,
• Al:
• 0.010% or more and 2.000% or less,
• N:
• 0.0100% or less, and
• optionally at least one selected from the group consisting of
• Sb:
• 0.200% or less,
• Sn:
• 0.200% or less,
• Ti:
• 0.200% or less,
• Nb:
• 0.200% or less,
• V:
• 0.100% or less,
• B:
• 0.0100% or less,
• Cu:
• 1.00% or less,
• Cr:
• 1.000% or less,
• Ni:
• 1.000% or less,
• Mo:
• 0.50% or less,
• Ta:
• 0.100% or less,
• W:
• 0.500% or less,
• Mg:
• 0.0200% or less,
• Zn:
• 0.020% or less,
• Co:
• 0.020% or less,
• Zr:
• 0.020% or less,
• Ca:
• 0.0200% or less,
• Ce:
• 0.0200% or less,
• Se:
• 0.0200% or less,
• Te:
• 0.0200% or less,
• Ge:
• 0.0200% or less,
• As:
• 0.0200% or less,
• Sr:
• 0.0200% or less,
• Cs:
• 0.0200% or less,
• Hf:
• 0.0200% or less,
• Pb:
• 0.0200% or less,
• Bi:
• 0.0200% or less, and
• REM:
• 0.0200% or less,
• with the balance being Fe and inevitable impurities;
• the steel microstructure comprising:
• a total area ratio of bainite and tempered martensite:
• 30% or more, and
• a volume fraction of retained austenite:
• more than 5%,
• the cladding metal comprising a chemical composition containing, by mass %,
• C:
• 0.100% or less,
• Si:
• 0.60% or less,
• Mn:
• 1.72% or more and 2.50% or less
• P:
• 0.001% or more and 0.100% or less,
• S:
• 0.0200% or less,
• Al:
• 0.010% or more and 0.100% or less,
• N:
• 0.0100% or less, and
• optionally at least one selected from the group consisting of
• Sb:
• 0.200% or less,
• Sn:
• 0.200% or less,
• Ti:
• 0.200% or less,
• Nb:
• 0.200% or less,
• V:
• 0.100% or less,
• B:
• 0.0100% or less,
• Cu:
• 1.00% or less,
• Cr:
• 1.000% or less,
• Ni:
• 1.000% or less,
• Mo:
• 0.50% or less,
• Ta:
• 0.100% or less,
• W:
• 0.500% or less,
• Mg:
• 0.0200% or less,
• Zn:
• 0.020% or less,
• Co:
• 0.020% or less,
• Zr:
• 0.020% or less,
• Ca:
• 0.0200% or less,
• Ce:
• 0.0200% or less,
• Se:
• 0.0200% or less,
• Te:
• 0.0200% or less,
• Ge:
• 0.0200% or less,
• As:
• 0.0200% or less,
• Sr:
• 0.0200% or less,
• Cs:
• 0.0200% or less,
• Hf:
• 0.0200% or less,
• Pb:
• 0.0200% or less,
• Bi:
• 0.0200% or less, and
• REM:
• 0.0200% or less,
• with the balance being Fe and inevitable impurities;
• the steel microstructure comprising:
• an area ratio of ferrite:
• 80% or more, wherein
• average Vickers hardness (HVL) of the cladding metal is 260 or less,
• the average Vickers hardness (HVL) of the cladding metal divided by average Vickers hardness (HVB) of the base metal is 0.80 or less,
• boundary roughness between the base metal and the cladding metal is 50 μm or less at a maximum height Ry;
• and
• a number of voids at a boundary between the base metal and the cladding metal is 20 or fewer per 10 mm of boundary length.