In a method for producing in particular structural components or chassis components for a motor vehicle by hot or semi-hot forming, a sheet metal blank is heated in a heating station at least in a first region from a starting temperature to a target temperature, and then the warm blank is transferred to a cooled pressing tool and is formed and press-hardened. The heating station includes at least one burner zone which includes at least one burner, in which zone the sheet metal blank is heated from the starting temperature to the target temperature, and at least one burner is operated with a combustion gas and an oxygen-containing gas and the sheet metal blank comes into direct contact with the burner flame.

A forming sheet metal part (1) for a vehicle frame includes: a first portion (2) being locally heat-softened after the sheet metal part (1) has been formed out. The part (1) further includes a dedicated three-dimensional distortion-absorbing area (4), defining an internal boundary (6) within which the first portion (2) is to be locally heat-softened after the sheet metal part (1) has been formed out. The distortion-absorbing area (4) is dimensioned such that once said locally heat-softening step has been performed, the internal boundary (6) is adjacent to the first portion (2) and encloses the first portion (2) to absorb the dimensional distortions induced by the locally heat-softened first portion. The invention further relates to a method for producing a forming sheet metal part (1).

A method or the like for manufacturing a steel plate component, capable of maintaining the overall strength of the component and preventing a delayed fracture from occurring at the same time is provided. A method for manufacturing a steel plate component is characterized in that the steel plate component is locally heated by a heating electrode, the heating electrode being disposed on one side of the steel plate component, and spaced from and directly opposed to a punched part of the steel plate. The steel plate component is a high-strength steel plate having a tensile strength class of 780 MPa or higher. A heating temperature is 500 to 830 C. The steel plate component is locally heated by high-frequency induction for a short time period of 10 seconds or shorter. The heating electrode is a coil larger than the punched part and has two turns or more for the punched part.

A galvanized steel sheet including a base steel sheet, and a zinc-based plating layer on the surface of the base steel sheet. The base steel sheet may include a first surface layer region corresponding to a depth of 25 m from an interface between the base steel sheet and the zinc-based plating layer in a thickness direction of the base steel sheet, and a second surface layer region adjacent to the first surface layer region and corresponding to a depth of 25 m to 50 m in the thickness direction of the base steel sheet. A fraction of ferrite contained in the first surface layer region is 55 area % or more, an average grain size of the ferrite contained in the first surface layer region is 2 to 10 m, and a fraction of ferrite contained in the second surface layer region is 30 area % or more.

A hot-dip galvanized steel sheet according to one aspect of the present invention comprises a base steel sheet and a hot-dip galvanized layer formed on the surface of the base steel sheet, wherein the difference between the average of the Mn/Si values of surface oxides present on a surface portion, which is the region from the interface between the hot-dip galvanized layer and the base steel sheet to a depth of 15 nm, and the average of the Mn/Si values of internal oxides, which are present in the region from the interface to a depth of 50-100 nm, can be 0.5 or more. Mn and Si of each oxide mean the amounts (wt %) of Mn and Si components in the oxide, which are measured by EDS, and the average of Mn/Si values means the averaged value of the Mn/Si values measured for each oxide.

An austenitic stainless steel material that has a passivation film on a surface is provided. The austenitic stainless steel material has a chemical composition consisting of, in mass %, C: 0.10% or less, Si: 1.0% or less, Mn: 8.0-10.0%, P: 0.030% or less, S: 0.003% or less, Cr: 15.0-18.0%, Ni: 7.0-9.0%, N: 0.15-0.25%, Al: 0.005-0.20%, Ca: 0.0005-0.01%, Cu: less than 1.0%, Mo: less than 1.0%, B: 0-0.0050%, Nb: 0-0.50%, Ti: 0-0.50%, V: 0-0.50%, W: 0-0.50%, Zr: 0-0.50%, Co: 0-0.50%, Mg: 0-0.005%, Ga: 0-0.005%, Hf: 0-0.10%, REM: 0-0.10%, and the balance: Fe and impurities. An f value, namely, [Ni+0.72Cr+0.88Mo+1.11Mn0.27Si+0.53Cu+12.93C+7.55N], is more than 29.5 and less than 32.5.

A hot-dip galvanized steel sheet according to one aspect of the present invention comprises a base steel sheet and a hot-dip galvanized layer formed on the surface of the base steel sheet, wherein the difference between the average of the Mn/Si values of surface oxides present on a surface portion, which is the region from the interface between the hot-dip galvanized layer and the base steel sheet to a depth of 15 nm, and the average of the Mn/Si values of internal oxides, which are present in the region from the interface to a depth of 50-100 nm, can be 0.5 or more. Mn and Si of each oxide mean the amounts (wt %) of Mn and Si components in the oxide, which are measured by EDS, and the average of Mn/Si values means the averaged value of the Mn/Si values measured for each oxide.

A high strength member according to the present invention is the high strength member having a bending ridge line portion formed from a steel sheet, the member having a tensile strength of 1470 MPa or higher, a residual stress of 300 MPa or lower in an end surface of the bending ridge line portion, and a Vickers hardness (HV) of 200 or higher and 450 or lower in the end surface of the bending ridge line portion.