Abstract: The invention relates to ultrahigh strength hot-rolled steel having a chemical composition consisting of, by weight: 0.05%?C?0.1% 0.7%?Mn?1.1% 0.5%?Cr?1.0% 0.05%?Si?0.3% 0.05%?Ti?0.1% Al?0.07% S?0.03% P?0.05% the remainder comprising iron and impurities resulting from the production thereof. Moreover, the inventive steel has a bainitic-martensitic structure which can contain up to 5% ferrite. The invention also relates to a method of producing bands of said steel.

Abstract: The invention relates to ultrahigh strength hot-rolled steel having a chemical composition consisting of, by weight: 0.05%=C=0.1%, 0.7%=Mn=1.1%, 0.5%=Cr=1%, 0.05%=Si=0.3%, 0.05=Ti=0.1%, Al=0.07, S=0.03%, P=0.05, the remainder comprising iron and impurities resulting from the production thereof. Moreover, the inventive steel has a bainitic-martensitic structure which can contain up to 5% ferrite. The invention also relates to a method of producing bands of said steel.

Abstract: Process for the production of a hot rolled metal strip of very high strength, usable for shaping and particularly for stamping, characterized in that a steel of the following weight composition: carbon, 0.12-0.25%; manganese, 1-2%; aluminum, 0.03-2.5%; silicon, 0.03-2%; chromium, 0.04-2%; phosphorus, 0.02-0.09%; sulfur optionally up to 0.01%; titanium up to 0.15%; niobium up to 0.15%; vanadium up to 0.15%; is subjected to: rolling at a temperature below 880° C.; a first short cooling, carried out over a time less than 10 seconds, a second controlled cooling with a cooling speed V ref1 comprised between 20° C./sec. and 150° C./sec., the temperature at the end of the second cooling being comprised between 700° C. and 750° C., holding at a temperature level, a third cooling, also controlled, whose speed is comprised between 20° C./sec. and 150° C./sec., the temperature at the end of the third cooling being comprised between 350° C. and 550° C.

Abstract: Process for the production of a hot rolled metal strip of very high strength, usable for shaping and particularly for stamping, characterized in that a steel of the following weight composition: carbon, 0.12-0.25%; manganese, 1-2%; aluminum, 0.03-2.5%; silicon, 0.03-2%; chromium, 0.04-2%; phosphorus, 0.02-0.09%; sulfur optionally up to 0.01%; titanium up to 0.15%; niobium up to 0.15%; vanadium up to 0.

Abstract: Process for the production of a hot rolled metal strip of very high strength, usable for shaping and particularly for stamping, characterized in that a steel of the following weight composition: carbon, 0.12-0.25%; manganese, 1-2%; aluminum, 0.03-2.5%; silicon, 0.03-2%; chromium, 0.04-2%; phosphorus, 0.02-0.09%; sulfur optionally up to 0.01%; titanium up to 0.15%; niobium up to 0.15%; vanadium up to 0.15%; is subjected to: rolling at a temperature below 880° C.; a first short cooling, carried out over a time less than 10 seconds, a second controlled cooling with a cooling speed V ref1 comprised between 20° C./sec. and 150° C./sec., the temperature at the end of the second cooling being comprised between 700° C. and 750° C., holding at a temperature level, a third cooling, also controlled, whose speed is comprised between 20° C./sec. and 150° C./sec., the temperature at the end of the third cooling being comprised between 350° C and 550° C.

Abstract: The invention provides a method of fabricating “TRIP” steel in the form of thin strip, wherein: a strip from 1.5 to 10 mm thick, preferably from 1 to 5 mm thick, is cast directly from liquid steel having the composition (in weight percent) C % from 0.05 to 0.25, (Mn+Cu+Ni) % from 0.5 to 3, (Si+Al) % from 0.1 to 4, (P+Sn+As+Sb) % not greater than 0.1, (Ti+Nb+V+Zr+rare earths) % less than 0.3, Cr % less than 1, Mo % less than 1, V % less than 1, the remainder being iron and manufacturing impurities; said strip is hot rolled on-line in one or more passes at a temperature higher than the Ar3 temperature of said steel and with a reduction ratio from 25 to 70%; first forced cooling of said strip is carried out at a cooling rate from 5 to 100° C./s; the strip remains at temperatures from 550 to 400° C.