Rolled steel that hardens by means of precipitation after hot-forming and/or quenching with a tool having very high strength and ductility, and method for manufacturing same

A rolled steel sheet or blank having a chemical composition comprising, expressed in percent by weight:

• C≦0.1%;
• 0.5%≦Mn≦7%;
• 0.5%≦Si≦3.5%;
• 0.5% Ti≦2%;
• 2%≦Ni≦7%;
• Al≦0.10%;
• Cr≦2%;
• Cu≦2%;
• Co≦2%;
• Mo≦2%;
• S≦0.005%;
• P≦0.03%;
• Nb≦0.1%;
• V≦0.1%;
• B<0.005%;
• and
• N≦0.008%,
• the levels of silicon and titanium being such that:
• Si
• +
• Ti
• ≥
• 2.5
• 
• %
• ,
• and
• Ti
• Si
• ≥
• 0.3
• ,
• a remainder of the composition consisting of iron and unavoidable impurities resulting from processing.

A rolled steel sheet or blank having a chemical composition comprising, expressed in percent by weight:

• C≦0.1%;
• 0.5%≦Mn≦7%;
• 0.5%≦Si≦3.5%;
• 0.5% Ti≦2%;
• 2%≦Ni≦7%;
• Al≦0.10%;
• Cr≦2%;
• Cu≦2%;
• Co≦2%;
• Mo≦2%;
• S≦0.005%;
• P≦0.03%;
• Nb≦0.1%;
• V≦0.1%;
• B<0.005%;
• and
• N≦0.008%,
• the levels of silicon and titanium being such that:
• Si
• +
• Ti
• ≥
• 2.5
• 
• %
• ,
• and
• Ti
• Si
• ≥
• 0.3
• ,
• a remainder of the composition including iron and unavoidable impurities resulting from processing.