Patent ID: 7708843

Claim:
A process for manufacturing a part having very high mechanical properties from a hot-rolled or cold-rolled steel strip comprising a steel, the process comprising the following successive steps: said steel strip is precoated with a precoat comprising aluminum or an aluminum alloy to obtain a coated strip having a steel/precoat interface; said coated strip is cold-deformed to obtain a cold-deformed part; optionally a portion is removed from said cold-deformed part; said cold-deformed part is heated so as to form an intermetallic compound starting from the steel/precoat interface and to austenitize the steel and thus obtain a heated part; said heated part is transferred to a tool; and said heated part is cooled in the tool to obtain a cooled part at a rate such that the steel in the cooled part has a quenched structure selected from the group consisting of a martensitic structure, a bainitic structure and a martensite-bainite structure, wherein the cooled part comprises an intermetallic coating on the steel having a quenched structure; and before said cold-deformed part is heated, the steel/precoat interface does not contain an intermetallic phase; and said precoat is formed by at least one aluminum or aluminum alloy electroplating step, by at least one aluminum or aluminum alloy chemical vapor deposition step, by at least one aluminum or aluminum alloy physical vapor deposition step, by at least one co-rolling step in which said steel strip is co-rolled with an aluminum or aluminum alloy foil, or by a combination of any two or more of said steps.