A steel part includes a steel sheet substrate and a coating on at least one surface of the steel sheet substrate. The coating includes between 0.2 and 0.7% by weight of Al, with a remainder of the metal coating being Zn and inevitable impurities. The steel sheet substrate and the coating have at least one deformation. An outer surface of the coating has a waviness Wa.sub.0.8 of less than or equal to 0.43 μm.

The present invention relates to a flat steel product which has good deep-drawing ability, low edge-crack sensitivity and good bending behaviour. To this end, the flat steel product contains a steel which consists of (in wt %) 0.1-0.5% C, 1.0-3.0% Mn, 0.9-1.5% Si, up to 1.5% Al, up to 0.008% N, up to 0.020% P, up to 0.005% S, 0.01-1% Cr and optionally one or more of the following elements: up to 0.2% Mo, up to 0.01% B, up to 0.5% Cu, up to 0.5% Ni and optionally a total of 0.005-0.2% microalloying elements, the remainder being iron and unavoidable impurities, wherein 75<(Mn2+55*Cr)/Cr<3000 where Mn is the Mn content of the steel in wt % and Cr is the Cr content of the steel in wt %. The steel has a structure which consists of at least 80 area % martensite, of which at least 75 area % is tempered martensite and at most 25 area % is non-tempered martensite, at least 5 volume % residual austenite, 0.5 to 10 area % ferrite and at most 5 area % bainite, wherein in the region of the phase boundary between tempered martensite and residual austenite there is a low-Mn ferrite seam which has a width of at least 4 nm and at most 12 nm and the Mn content of which is at most 50% of the average Mn content of the flat steel product. The flat steel product contains carbides with a length of less than or equal to 250 nm. The invention also relates to a method for producing a flat steel product according to the invention, in which method the structural characteristics of the flat steel product according to the invention are set by suitable heat treatment.

A coated metal sheet includes a steel substrate and a coating on at least one surface of the steel substrate. The coating includes between 0.2 and 0.7% by weight of Al, with a remainder of the metal coating being Zn and inevitable impurities. The coated metal sheet was subjected to a skin pass operation after coating. An outer surface of the metal coating has a waviness Wa.sub.0.8 of less than or equal to 0.55 μm.

A method for producing a high strength steel sheet having a yield strength YS of at least 850 MPa, a tensile strength TS of at least 1180 MPa, a total elongation of at least 14% and a hole expansion ratio HER of at least 30%. The chemical composition of the steel contains: 0.15%≤C≤0.25%, 1.2%≤Si≤1.8%, 2%≤Mn≤2.4%, 0.1%≤Cr≤0.25%, Nb≤0.05%, Ti≤0.05%, Al≤0.50%, the remainder being Fe and unavoidable impurities. The sheet is annealed at an annealing temperature TA higher than Ac3 but less than 1000° C. for more than 30 s, by cooling it to a quenching temperature QT between 275° C. and 325° C., at a cooling speed sufficient to have, just after quenching, a structure consisting of austenite and at least 50% of martensite, the austenite content en.) being such that the final structure can contain between 3% and 15% of residual austenite and between 85 and 97% of the sum of martensite and bainite, without ferrite, heated to a partitioning temperature PT between 420° C. and 470° C. and maintained at this temperature for time between 50 s and 150 s and cooled to the room temperature.

The high-strength hot-dip galvanized steel sheet, which includes a hot-dip galvanized coating layer on a surface of the steel sheet, has a component composition containing, in mass %, C: 0.07% to 0.20%, Si: 0.1% to 2.0%, Mn: 2.0% to 3.5%, P: 0.05% or less, S: 0.05% or less, and sol. Al: 0.005% to 0.1%, with the balance being Fe and incidental impurities; and has a steel microstructure containing, in area fraction, 60% or less of ferrite, 40% or more of tempered martensite, and 10% or less of fresh martensite and having a void number density of 1,500/mm.sup.2 or less in a bent portion in the VDA bending test.

A hot-rolled steel is described having a yield strength (Rp0.2) of at least 1100 MPa along and/or transverse to a rolling direction which has a chemical composition of (in mass-%): C: 0.10-0.2, Si: 0-0.7, Mn: 1.1-2.2, Nb: 0-0.06, Ti: 0-0.15, V: more than 0.03 and ≤0.25, Al: 0.01-0.15, B: 0.0005-0.010, Cr: 0.1-1.7, Mo: 0.15-0.8, Cu: 0-1.5, Ni: 0.3-2.5, P: 0-0.015, S: 0-0.008 Zr: 0-0.2, Ca: 0-0.004, the balance Fe and unavoidable impurities, whereby a) when 0.1<C<0.11 then Mn≥1.6 and V>0.14 and Mo≥0.5 (in mass-%), b) when 0.11≤C<0.125 then Mn≥1.45 and V≥0.13 and Mo≥0.35 (in mass-%), c) when 0.125≤C<0.15, then Mn≥1.35 and V≥0.12 and Mo≥0.20 (in mass-%), and d) when C≥0.15 and V>0.11, then Mn≥1.3 and Mo≥0.15 (in mass-%) or when C≥0.15 and V 0.03-0.11, then Mn>1.3 and Mo>0.15 and Nb>0.02 and Cr+Cu+Ni>1.4 (in mass-%).

The present disclosure provides a hot-press formed part comprising a plated steel sheet and an aluminum alloy plated layer formed on the plated steel sheet, wherein the aluminum alloy plated layer comprises: an alloying layer (I) formed on the plated steel sheet and containing, by weight %, 5-30% of Al; an alloying layer (II) formed on the alloying layer (I) and containing, by weight %, 30 to 60% of Al; an alloying layer (III) formed on the alloying layer (II) and containing, by weight %, 20-50% of Al and 5-20% of Si; and an alloying layer (IV) formed continuously or discontinuously on at least a part of the surface of the alloying layer (III), and containing 30-60% of Al, wherein the rate of the alloying layer (III) exposed on the outermost surface of the aluminum alloy plated layer is 10% or more.

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.

A steel sheet having a specified chemical composition and a tensile strength of 1,320 MPa or more, and methods for producing the steel sheet. The steel sheet has a specified microstructure including martensite and bainite, the total area fraction of the martensite and the bainite being 95% or more and 100% or less, the balance being one or more selected from ferrite and retained austenite. The forumulae [% Ti]+[% Nb]>0.007 and [% Ti]×[% Nb].sup.2≤7.5×10.sup.−6 are satisfied in the chemical composition.

A high strength cold rolled steel sheet having excellent burring properties includes: by weight %, 0.13-0.25% of carbon (C), 1.0-2.0% of silicon (Si), 1.5-3.0% of manganese (Mn), 0.08-1.5% of aluminum (Al)+chrome (Cr)+molybdenum (Mo), 0.1% or less of phosphorus (P), 0.01% or less of sulfur (S), 0.01% or less of nitrogen (N), and the balance of Fe and inevitable impurities; and, by area fraction, 3-25% of ferrite, 20-40% of martensite, 5-20% of residual austenite. The ferrite has an average grain size of 2 μm or less at the reference point of 4/t (wherein t refers to a steel sheet thickness), with the average ratio between lengths in the thickness direction and in the rolling direction being 1.5 or less.