An air knife includes: a nozzle main body provided so as to inject gas in response to the width of the steel plate; a nozzle lip installed on at least one of the upper section and the lower section of an outlet of the nozzle main body and extending inclinedly so that the injection cross-sectional area of the gas becomes narrow; and at least one moment generation unit, provided at one side of the nozzle lip, for generating a rotation moment so that the nozzle lip is curved in the width direction of the steel plate and a gap between other nozzle lips varies.

An air knife includes: a nozzle main body provided so as to inject gas in response to the width of the steel plate; a nozzle lip installed on at least one of the upper section and the lower section of an outlet of the nozzle main body and extending inclinedly so that the injection cross-sectional area of the gas becomes narrow; and at least one moment generation unit, provided at one side of the nozzle lip, for generating a rotation moment so that the nozzle lip is curved in the width direction of the steel plate and a gap between other nozzle lips varies.

This invention provides process for manufacturing a galvanized metal three-dimensional object with a shape including multiple edges, said process comprising, in the following order, the steps of: (A) providing and cutting a metal sheet matrix with a thickness within a range from 0.8 mm to 6 mm, the shape of said metal sheet matrix including multiple free edges, (B) batch-wise hot dipping said metal sheet matrix into a molten zinc alloy galvanizing bath, (C) cold-forming the galvanized metal sheet matrix into a desired three-dimensional shape including multiple adjacent metal edges, and (D) cold-forming a series of joining points for fastening together said multiple adjacent metal edges, to form said galvanized metal three-dimensional object.

This invention provides process for manufacturing a galvanized metal three-dimensional object with a shape including multiple edges, said process comprising, in the following order, the steps of: (A) providing and cutting a metal sheet matrix with a thickness within a range from 0.8 mm to 6 mm, the shape of said metal sheet matrix including multiple free edges, (B) batch-wise hot dipping said metal sheet matrix into a molten zinc alloy galvanizing bath, (C) cold-forming the galvanized metal sheet matrix into a desired three-dimensional shape including multiple adjacent metal edges, and (D) cold-forming a series of joining points for fastening together said multiple adjacent metal edges, to form said galvanized metal three-dimensional object.

Methods of strengthening surface regions of high-strength transformation induced plasticity (TRIP) steel are provided. The method may comprise shot peening at least one region of an exposed surface of a hot-formed press-hardened component comprising a high-strength steel. Prior to shot peening, the component has a microstructure comprising about 5% by volume retained austenite in a matrix of martensite. The shot peening is conducted at a temperature of about 150 C. and forms at least one hardened surface region comprising about 2% by volume austenite. The TRIP steel may be zinc-coated and having a surface coating comprising zinc and substantially free of liquid metal embrittlement (LME). Zinc-coated hot-formed press-hardened components, including automotive components, formed from such methods are also provided.

Methods of strengthening surface regions of high-strength transformation induced plasticity (TRIP) steel are provided. The method may comprise shot peening at least one region of an exposed surface of a hot-formed press-hardened component comprising a high-strength steel. Prior to shot peening, the component has a microstructure comprising about 5% by volume retained austenite in a matrix of martensite. The shot peening is conducted at a temperature of about 150 C. and forms at least one hardened surface region comprising about 2% by volume austenite. The TRIP steel may be zinc-coated and having a surface coating comprising zinc and substantially free of liquid metal embrittlement (LME). Zinc-coated hot-formed press-hardened components, including automotive components, formed from such methods are also provided.

A pneumatic brake booster in which, for improving the sealing and simplifying the assembly of sealing elements, it is proposed that the booster housing in the bearing region of at least one sealing element has a metal coating having a surface roughness Ra>1.2.

A pneumatic brake booster in which, for improving the sealing and simplifying the assembly of sealing elements, it is proposed that the booster housing in the bearing region of at least one sealing element has a metal coating having a surface roughness Ra>1.2.

A steel sheet with a metallic coating is provided. A composition of the metallic coating includes from 2.0 to 24.0% by weight of zinc, from 7.1 to 12.0% by weight of silicon, optionally from 1.1 to 8.0% by weight of magnesium, and optionally additional elements chosen from Pb, Ni, Zr, or Hf. The content by weight of each additional element is less than 0.3%. A balance of the composition is aluminum, unavoidable impurities and residual elements. A ratio Al/Zn is from 4.0 to 6.0.

A hot-dip galvanized steel sheet includes: a predetermined chemical composition; and a steel structure represented by: in terms of area ratio, polygonal ferrite: 10% or less; upper bainite: 20% or less; retained austenite: 5% or less; and martensite: 70% or more, in which: martensite having Fe carbides at a number density of 110.sup.6/mm.sup.2 or more is contained by 50% or more, in terms of area ratio, with respect to the entire amount of martensite; and the steel structure has an average effective crystal grain diameter of 5.0 m or less.