Abstract: A coated steel sheet and press hardened steel part having a composition including, by weight percent: C 0.26-0.40%, Mn 0.5-1.8%, Si 0.1-1.25%, Al 0.01-0.1%, Cr 0.1-1.0%, Ti 0.01-0.1%, B 0.001-0.004%, P 0.020%, S 0.010%, N 0.010% the remainder of the composition being iron and unavoidable impurities resulting from the smelting. The press hardened steel part includes a bulk having a microstructure including, in surface fraction, more than 95% of martensite and less than 5% of bainite, a coating layer at the surface of the steel part, a ferritic interdiffusion layer between the coating layer and the bulk, and a ratio between the ferritic grain width in the interdiffusion layer GWint over prior austenite grain size in the bulk PAGSbulk, satisfying following equation (GWint/PAGSbulk)?1?30%.

Abstract: A painted steel part includes a steel sheet precoated with a metallic coating and hot formed, the coating including: 2.0 to 24.0% by weight of zinc; 1.1 to 7.0% by weight of silicon; optionally from 0.5 to 3.0% by weight of magnesium when the amount of silicon is between 1.1 and 4.0%, and optionally additional elements chosen from Pb, Ni, Zr or Hf, a content by weight of each additional element being less than 0.3% by weight, a balance being aluminum, unavoidable impurities and residual elements resulting from feeding ingots or from a passage of the steel sheet in a molten bath; and a ratio Al/Zn by weight greater than 2.9; and a paint layer.

Abstract: A hot formed pre-coated steel part includes a steel sheet precoated with a metallic coating and hot formed, the coating including: 2.0 to 24.0% by weight of zinc; 1.1 to 7.0% by weight of silicon; optionally from 0.5 to 3.0% by weight of magnesium when the amount of silicon is between 1.1 and 4.0%, and optionally additional elements chosen from Pb, Ni, Zr or Hf, a content by weight of each additional element being less than 0.3% by weight, a balance being aluminum, unavoidable impurities and residual elements resulting from feeding ingots or from a passage of the steel sheet in a molten bath; and a ratio Al/Zn by weight greater than 2.9, where a microstructure in the steel after said hot forming being martensitic or martensitic-bainitic or made of at least 75% of equiaxed ferrite, 5 to 20% of martensite and bainite in an amount less than or equal to 10%.

Abstract: A method for manufacture of a pre-coated steel sheet includes providing a steel sheet, coating the steel sheet with a metallic coating, the metallic coating including: 2.0 to 24.0% by weight of zinc; 1.1 to 7.0% by weight of silicon; optionally from 0.5 to 3.0% by weight of magnesium when the amount of silicon is between 1.1 and 4.0%, and optionally additional elements chosen from Pb, Ni, Zr or Hf, a content by weight of each additional element being less than 0.3% by weight, a balance of the metallic coating being aluminum, unavoidable impurities and residual elements resulting from feeding ingots or from a passage of the steel sheet in a molten bath; a ratio Al/Zn by weight greater than 2.

Abstract: A pre-coated steel sheet includes a steel sheet precoated with a metallic coating, the coating including: 2.0 to 24.0% by weight of zinc; 1.1 to 7.0% by weight of silicon; optionally from 0.5 to 3.0% by weight of magnesium when the amount of silicon is between 1.1 and 4.0%, and optionally additional elements chosen from Pb, Ni, Zr or Hf, a content by weight of each additional element being less than 0.3% by weight, a balance being aluminum, unavoidable impurities and residual elements resulting from feeding ingots or from a passage of the steel sheet in a molten bath; a ratio Al/Zn by weight greater than 2.9, wherein the coating does not include In and the coating does not include Sn.

Abstract: The present invention provides a method for the manufacture of a hardened part. The method includes the provision of a steel sheet pre-coated with a metallic coating including from 2.0 to 24.0% by weight of zinc, from 1.1 to 7.0% by weight of silicon, optionally from 1.1 to 8.0% by weight of magnesium when the amount of silicon is between 1.1 and 4.0%, and optionally additional elements chosen from Pb, Ni, Zr, or Hf, the content by weight of each additional element being less than 0.3% by weight, the balance being aluminum and unavoidable impurities and residuals elements, wherein the ratio Al/Zn is above 2.9. The method further includes the cutting of the coated steel sheet to obtain a blank, the thermal treatment of the blank at a temperature between 840 and 950° C.

Abstract: The present invention provides a method for the manufacture of a hardened part. The method includes the provision of a steel sheet pre-coated with a metallic coating including from 2.0 to 24.0% by weight of zinc, from 1.1 to 7.0% by weight of silicon, optionally from 1.1 to 8.0% by weight of magnesium when the amount of silicon is between 1.1 and 4.0%, and optionally additional elements chosen from Pb, Ni, Zr, or Hf, the content by weight of each additional element being less than 0.3% by weight, the balance being aluminum and unavoidable impurities and residuals elements, wherein the ratio Al/Zn is above 2.9. The method further includes the cutting of the coated steel sheet to obtain a blank, the thermal treatment of the blank at a temperature between 840 and 950° C.