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Abstract

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 T_i comprised between T_e−10° C. and T_e, Te being the eutectic or solidus temperature of the precoating, then heating the blank from the temperature T_i up to a temperature T_m comprised between 840 and 950° C. under non protective atmosphere with a heating rate V comprised between 30° C./s and 90° C./s, V being the heating rate between the temperature T_i and the temperature T_m, in order to obtain a coated heated blank, then soaking the coated heated blank at said temperature T_m for a time t_m comprised 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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First Claim