Coated hot- and cold-rolled steel sheet comprising a very high resistance after thermal treatment

A hot-rolled coated steel sheet comprising a hot-rolled steel sheet coated with an aluminum or aluminum alloy coating, wherein said coated steel sheet is in the form of a delivery coil and the steel in the sheet comprises the following composition by weight:

• 0.15%<carbon<0.5%
• 0.5%<manganese<3%
• 0.1%<silicon<0.5%
• 0.01%<chromium<1%
• titanium<0.2%
• aluminum<0.1%
• phosphorus<0.1%
• sulfur<0.05%
• 0.0005%<boron<0.08%, the remainder being iron and impurities inherent in processing, and the steel sheet has a very high mechanical resistance in excess of 1500 MPa after thermal treatment and the aluminum or aluminum alloy coating provides a high resistance to corrosion of the steel sheet.

A hot-rolled coated steel sheet comprising a hot-rolled steel sheet coated with an aluminum or aluminum alloy coating, wherein the steel in the sheet comprises the following composition by weight:

• 0.15%<carbon<0.5%
• 0.5%<manganese<3%
• 0.1%<silicon<0.5%
• 0.01%<chromium<1%
• titanium<0.2%
• aluminum<0.1%
• phosphorus<0.1%
• sulfur<0.05%
• 0.0005%<boron<0.08%, the remainder being iron and impurities inherent in processing, and the steel sheet has a very high mechanical resistance in excess of 1500 MPa after a subsequent thermal treatment, and the aluminum or aluminum alloy coating provides a high resistance to corrosion and prevents decarburization during said subsequent thermal treatment of the steel sheet.