A roll-bonded clad metal sheet and a method for producing a roll-bonded clad metal sheet is provided. The roll-bonded clad sheet includes a metallic base material layer and a metallic cladding material layer which are joined to one another by a metallurgical bond. The metallic cladding material layer includes a nickel-based material whose chemical composition includes, in % by mass, a proportion of more than 50% of Ni and a proportion of 3.1% of Nb. The metallurgical bond is obtained by a thermomechanical rolling process including a first rolling phase for prerolling, a second rolling phase for final forming and a cooling time between the first rolling phase and the second rolling phase, wherein a final rolling temperature of the second rolling phase is set to a value equal to or less than 880 C.

A steel sheet has a microstructure that contains ferrite in an area ratio of 20% or more, martensite in an area ratio of 5% or more, and tempered martensite in an area ratio of 5% or more. The ferrite has a mean grain size of 20.0 m or less. An inverse intensity ratio of -fiber to -fiber in the ferrite is 1.00 or more and an inverse intensity ratio of -fiber to -fiber in the martensite and the tempered martensite is 1.00 or more.

A steel sheet includes a hot-dip galvanized layer or a galvannealed layer on a surface of the steel sheet, the steel sheet including: in mass %, C: 0.06% or more and 0.22% or less; Si: 0.50% or more and 2.00% or less; Mn: 1.50% or more and 2.80% or less; Al: 0.02% or more and 1.00% or less; P: 0.001% or more and 0.100% or less; S: 0.0005% or more and 0.0100% or less; N: 0.0005% or more and 0.0100% or less; and a balance: Fe and impurities.

A steel sheet has a predetermined chemical composition and a metal structure represented by, in area fraction, polygonal ferrite: 40% or less, martensite: 20% or less, bainitic ferrite: 50% to 95%, and retained austenite: 5% to 50%. In area fraction, 80% or more of the bainitic ferrite is composed of bainitic ferrite grains that have an aspect ratio of 0.1 to 1.0 and have a dislocation density of 810.sup.2 (cm/cm.sup.3) or less in a region surrounded by a grain boundary with a misorientation angle of 15 or more. In area fraction, 80% or more of the retained austenite is composed of retained austenite grains that have an aspect ratio of 0.1 to 1.0, have a major axis length of 1.0 m to 28.0 m, and have a minor axis length of 0.1 m to 2.8 m.

Provided are a metal sheet, a method of producing a metal sheet, a method of producing a molded product of a metal sheet, and a molded product of a metal sheet, in which occurrence of surface roughness is inhibited. Provided are a metal sheet satisfying conditions (a1), (b1) or (c1) at the surface and a method for producing the metal sheet. Also provided are a method for producing a molded product of a metal sheet using the metal sheet, and a molded product of the metal sheet. (a1) The area fraction of crystal grains having a crystal orientation divergent by 20 or more from a (111) plane and by 20 or more from a (001) plane is from 0.25 to 0.35, and the average crystal grain size is less than 16 m. (b1) The area fraction of crystal grains having a crystal orientation divergent by 20 or more from a (111) plane and by 20 or more from a (001) plane is from 0.15 to 0.30, and the average crystal grain size is 16 m or more. (c1) The area fraction of crystal grains with a Taylor Factor value from 3.0 to 3.4, when assuming plane strain tensile deformation in the transverse direction, is from 0.18 to 0.40.

The disclosure relates to a method for welding steel sheets made of steel materials coated with an aluminum silicon anti-corrosion layer, in particular CMnB and CMn steel materials that can be hardened using the quench hardening method, wherein a welding filler rod is used in the welding of the sheets and the welding filler rod has the composition: C=0.80-2.28% C base material, Cr=8-20, Ni<5, Si=0.2-1, Mn=0.2-1, Mo<2, with the rest being composed of iron and unavoidable smelting-related impurities and with all indications expressed in % by mass.

A high-strength galvanized steel sheet of the present invention includes a steel sheet having a specific chemical composition, and a steel structure containing, in terms of area ratio, 4% or more and 20% or less of retained austenite, 30% or less (including 0%) of ferrite, 40% or more of martensite, and 10% or more and 50% or less of bainite; and a galvanized layer provided on the steel sheet, in which an amount of diffusible hydrogen in the steel is less than 0.20 mass ppm, a tensile strength is 1100 MPa or more, a relationship between a tensile strength TS (MPa), an elongation El (%), and a sheet thickness t (mm) satisfies a (1) formula below, and a yield ratio YR is 67% or more.

TS(El+32.5t)13000 (1)

A dual-hardness clad steel plate. One surface of the steel plate is a high-hardness layer, the other surface of the steel plate is a low-hardness layer, and a combination of atoms is achieved between the high-hardness layer and the low-hardness layer by rolling bonding, wherein Mn13 steel is adopted for the low-hardness layer, and the Brinell hardness of the high-hardness layer is greater than 600. Further disclosed is a production method of the dual-hardness clad steel plate, comprising: 1) respectively preparing a high-hardness layer slab and a low-hardness layer slab; 2) assembling: preprocessing combined faces of the slabs, carrying out peripheral welded sealing on joint faces of the slabs, and carrying out vacuumizing treatment on a composite slab after welded sealing; 3) heating; 4) carrying out composite rolling; 5) cooling; and 6) carrying out thermal treatment, wherein the heating temperature is 1050-1100 C., the heating time is 2-3 min/mmslab thickness, and water cooling is performed on the heated slab, and the water temperature is lower than 40 C. The steel plate has different hardness characteristics and good low-temperature toughness.

A cold-rolled and heat-treated steel sheet-having a microstructure consisting of, in surface fraction: between 10% and 30% of retained austenite, said retained austenite being present as films having an aspect ratio of at least 3 and as Martensite Austenite islands, less than 8% of such Martensite A islands having a size above 0.5 m, at most 1% of fresh martensite at most 50% of tempered martensite and recovered martensite containing precipitates of at least one element chosen among niobium, titanium and vanadium.

It also provides a manufacturing method thereof.

A steel sheet for cans has a chemical composition containing, by mass %, C: 0.015% or more and 0.150% or less, Si: 0.04% or less, Mn: 1.0% or more and 2.0% or less, P: 0.025% or less, S: 0.015% or less, Al: 0.01% or more and 0.10% or less, N: 0.0005% or more and less than 0.0050%, Ti: 0.003% or more and 0.015% or less, B: 0.0010% or more and 0.0040% or less, and the balance being Fe and inevitable impurities. The steel sheet has a microstructure including a ferrite phase as a main phase and at least one of a martensite phase and a retained austenite phase as a second phase, the total area fraction of the second phase being 1.0% or more, and the sheet has a tensile strength of 480 MPa or more, a total elongation of 12% or more, and a yield elongation of 2.0% or less.