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FABRICATION PROCESS OF COATED STAMPED PARTS AND PARTS PREPARED FROM THE SAME

  • US 20120085467A1
  • Filed: 02/01/2010
  • Published: 04/12/2012
  • Est. Priority Date: 02/02/2009
  • Status: Active Grant
First Claim
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1. 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, said precoating containing more than 50% of free aluminium and having a thickness selected to enable alloying with said steel substrate, said thickness being preferably comprised between 15 and 50 micrometers, thencutting said steel sheet to obtain a precoated steel blank, thenheating said blank under a non protective atmosphere up to a temperature Ti near the melting temperature of said precoating, said temperature Ti being preferably comprised between Te

    10°

    C. and Te, where Te is the eutectic or solidus temperature of said precoating, thenheating said blank from said temperature Ti up to an austenitization temperature Tm of said steel substrate, said temperature Tm being preferably comprised between 840 and 950°

    C., under a non-protective atmosphere at a heating rate V comprised between 30°

    C./s and 90°

    C./s, V being the heating rate between said temperature Ti and said temperature Tm, in order to obtain a coated heated blank, thensoaking said coated heated blank at said temperature Tm for a time tm, comprised between 20 s and 90 s, thenhot stamping said 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 said steel substrate comprising at least one constituent chosen among martensite or bainite.

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