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

摘要

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 Ti comprised between Te- 10°C and Te, Te being the eutectic or solidus temperature of the precoating, then heating the blank from the temperature Ti up to a temperature Tm 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 Ti and the temperature Tm, in order to obtain a coated heated blank, then soaking the coated heated blank at said temperature Tm for a time tm comprised between 20s and 90s, 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.