Abstract: A method for the fabrication of a hot rolled steel includes providing a liquid metal comprising a certain chemical composition; carrying out a vacuum or SiCa treatment, the chemical composition including, expressed by weight 0.0005%?Ca?0.005%, if a SiCA treatment is carried out; dissolving quantities of Ti and N in the liquid metal so as to satisfy (% [Ti])×(% [N])<6.10?4%2; casting the steel to obtain a cast semi-finished product; rolling the cast semi-finished product with an end-of-rolling temperature between 880° C. and 930° C., a reduction rate of the penultimate pass being less than 0.25, and a start-of-rolling temperature of the penultimate pass being less than 960° C. to obtain a hot-rolled product, then cooling the hot rolled product at a rate between 20 and 150° C./s to obtain a hot rolled steel sheet; and coiling the hot rolled product to obtain a hot rolled steel sheet.

Abstract: A method for the fabrication of a hot rolled steel includes providing a liquid metal comprising a certain chemical composition; carrying out a vacuum or SiCa treatment, the chemical composition including, expressed by weight 0.0005%?Ca?0.005%, if a SiCA treatment is carried out; dissolving quantities of Ti and N in the liquid metal so as to satisfy (% [Ti])×(% [N])<6.10?4%2; casting the steel to obtain a cast semi-finished product; rolling the cast semi-finished product with an end-of-rolling temperature between 880° C. and 930° C., a reduction rate of the penultimate pass being less than 0.25, and a start-of-rolling temperature of the penultimate pass being less than 960° C. to obtain a hot-rolled product, then cooling the hot rolled product at a rate between 20 and 150° C./s to obtain a hot rolled steel sheet; and coiling the hot rolled product to obtain a hot rolled steel sheet.

Abstract: The present invention provides a hot rolled steel sheet with yield stress greater than 680 MPa and less than or equal to 840 MPa a tensile strength between 780 MPa and 950 MPa, elongation at failure greater than 10% and hole-expansion ratio (Ac) greater than or equal to 45%. The chemical composition includes, with the contents expressed by weight: 0.05%?Mo?0.35%, 0.15<C?0.6% when 0.05%?Mo?0.11%, or 0.10%?Cr?0.6% when 0.11%<Mo?0.35%. The microstructure includes at least 70% granular bainite, less than 20% ferrite, with the remainder, if any, including lower bainite, martensite and residual austenite. The sum of the martensite and residual austenite contents is less than 5%.

Abstract: The present invention provides a hot rolled steel sheet. The hot rolled steel sheet has a yield stress greater than 680 MPa and less than or equal to 840 MPa, at least in a direction transverse to a rolling direction, strength between 780 MPa and 950 MPa, elongation at failure greater than 10% and hole-expansion ratio (Ac) greater than or equal to 45%. The chemical composition includes, with the contents expressed by weight: 0.04%?C?0.08% 1.2%?Mn?1.9% 0.1%?Si?0.3% 0.07%?Ti?0.125% 0.05%?Mo?0.35% 0.15%<Cr?0.6% when 0.05%?Mo?0.11%, or 0.10%?Cr?0.6% when 0.11%<Mo?0.35% Nb?0.045% 0.005%?Al?0.1% 0.002%?N?0.01% S?0.004% P?0.020% and optionally 0.001%?V?0.2%. The remainder includes iron and unavoidable impurities resulting from processing. The microstructure includes granular bainite, the area percentage of which is greater than 70%, and ferrite, the area percentage of which is less than 20%, with the remainder, if any, including lower bainite, martensite and residual austenite.

Abstract: A hot rolled steel sheet with a yield stress greater than 690 MPa and less than or equal to 840 MPa, with strength between 780 MPa and 950 MPa, elongation at failure greater than 10% and a hole expansion ratio (Ac) greater than or equal to 50% is described. Methods for the fabrication of the sheet are also described.

Abstract: The invention relates principally to a hot rolled steel sheet with a yield stress greater than 690 MPa and less than or equal to 840 MPa, with strength between 780 MPa and 950 MPa, elongation at failure greater than 10% and a hole expansion ratio (Ac) greater than or equal to 50%. The chemical composition of the sheet claimed by the invention contains, whereby the contents are expressed in percent by weight: 0.40%?C?0.065%, 1.4%?Mn?1.9%, 0.1%?Si?0.55%, 0.095%?Ti?0.145%, 0.025%?Nb?0.045%, 0.005%?Al?0.1%, 0.002%?N?0.007%, S?0.004%, P<0.020. The microstructure of the sheet claimed by the invention also consists of granular bainite, ferrite, cementite in an area percentage of less than 1.5% and titanium and niobium carbonitrides, which results in a hole expansion ratio (Ac) greater than or equal to 50%, and the ratio between the grain size DL measured parallel to the rolling direction and the grain size DN measured perpendicular to the rolling direction is less than or equal to 1.4.