Arcelormittal

Arcelormittal Investigacion Y Desarrollo, S.l.

Audi Ag

Volkswagen Ag

Raisa Grigorieva

Pascal Drillet

Thierry Sturel

Brahim Nabi

Florin Duminica

Christian Allely

Tiago Machado Amorim

David Dussaussois

Uwe Paar

Ludwig Schaller

Karl Michael Bader

Isabelle Thirion

Michael Alsmann

Thomas Vietoris

Cédric Georges

Cedric Georges

A press hardening method including the following steps: A. the provision of a steel sheet for heat treatment being optionally coated with a zinc- or aluminum-based pre-coating, B. the flexible rolling of the steel sheet in the rolling direction so as to obtain a steel sheet having a variable thickness, C. the cutting of the rolled steel sheet to obtain a tailored rolled blank, D. the deposition of a hydrogen barrier pre-coating over a thickness from 10 to 550 nm, E. the heat treatment of the tailored rolled blank to obtain a fully austenitic microstructure in the steel, F. the transfer of the tailored rolled blank into a press tool, G. the hot-forming of the tailored rolled blank to obtain a part having a variable thickness,H. the cooling of the part having a variable thickness obtained at step G).

Press hardening method

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%.

Hot formed pre-coated steel part

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.

Coated steel sheet

A press hardening method includes the following steps: A. the provision of a steel sheet for heat treatment, precoated with a zinc- or aluminum-based pre-coating for anti-corrosion purpose, B. the deposition of a hydrogen barrier pre-coating over a thickness from 10 to 550 nm, C. the batch annealing of the precoated steel sheet in an inert atmosphere to obtain a pre-alloyed steel sheet, D. the cutting of the pre-alloyed steel sheet to obtain blank, E. the thermal treatment of the blank to obtain a fully austenitic microstructure in the steel, F. the transfer of the blank into a press tool, G. the hot-forming of the blank to obtain a part, H. the cooling of the part obtained at step G).

press hardening method includes the following steps: A. the provision of a steel sheet for heat-treatment, precoated with a zinc- or aluminum-based pre-coating, B. the deposition of a hydrogen barrier pre-coating over a thickness from 10 to 550 nm, and comprising at least one element chosen from among: nickel, chromium, magnesium, aluminum and yttrium, C. batch annealing of the precoated steel sheet to obtain a pre-alloyed steel sheet, the cooling after the batch annealing being performed at a speed of 29.0° C.hor less, D. the cutting of the pre-alloyed steel sheet to obtain blank, E. thermal treatment of the blank to obtain a fully austenitic microstructure in the steel, F. the transfer of the blank into a press tool, G. the hot-forming of the blank to obtain a part, H. the cooling of the part obtained at step G).

A press hardening method includes the following steps providing a carbon steel sheet coated with a barrier pre-coating including nickel and chromium wherein the weight ratio Ni/Cr is between 1.5 and 9, cutting the sheet to obtain a blank, thermal treatment of the blank in an atmosphere having an oxidizing power equal or higher than that of an atmosphere consisting of 1% by volume of oxygen and equal or smaller than that of an atmosphere consisting of 50% by volume of oxygen, such atmosphere having a dew point between &#x2212;30 and +30&#xb0; C., transfer of the blank into a press tool, hot-forming of the blank to obtain a part, cooling of the part to obtain a microstructure in steel being martensitic or martensito-bainitic or made of at least 75 wt. % of equiaxed ferrite, from 5 to 20 wt. % of martensite and bainite in amount less than or equal to 10 wt. %.

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&#xb0; C. to obtain a fully austenitic microstructure in the steel, the transfer of the blank into a press tool, the hot-forming of the blank to obtain a part, the cooling of the part in order to obtain a microstructure in steel being martensitic or martensitic-bainitic or made of at least 75% of equiaxed ferrite, from 5 to 20% of martensite and bainite in amount less than or equal to 10%.

Method for the manufacture of a hardened part which does not have LME issues

A manufacturing process of a hot stamped coated part comprising the following successive steps, in this order: providing a hot rolled or cold rolled steel sheet comprising a steel substrate and an aluminium-silicon alloy precoating, the precoating containing more than 50% of free aluminium and having a thickness comprised between 15 and 50 micrometers, then cutting the steel sheet to obtain a precoated steel blank, then heating the blank under non protective atmosphere up to a temperature Tcomprised between T&#x2212;10&#xb0; C. and T, Te being the eutectic or solidus temperature of the precoating, then heating the blank from the temperature Tup to a temperature Tcomprised between 840 and 950&#xb0; C. under non protective atmosphere with a heating rate V comprised between 30&#xb0; C./s and 90&#xb0; C./s, V being the heating rate between the temperature Tand the temperature T, in order to obtain a coated heated blank, then soaking the coated heated blank at said temperature Tfor a time tcomprised between 20 s and 90 s, then hot stamping the blank in order to obtain a hot stamped coated part, then cooling said stamped part at a cooling rate in order to form a microstructure in the steel substrate comprising at least one constituent chosen among martensite or bainite.

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Metz, France

Raisa Grigorieva