Hot-rolled high-strength steel strip

A hot-rolled high-strength steel strip having a composition having, in wt. %,

• C:
• 0.06-0.12 wt. %,
• Mn:
• 1.20-2.20 wt. %,
• Ti:
• 0.07-0.15 wt. %,
• Si:
• up to 0.65 wt. %,
• Al:
• up to 0.10 wt. %,
• P:
• up to 0.02 wt. %,
• S:
• up to 0.01 wt. %,
• Nb:
• up to 0.03 wt. %,
• N:
• up to 0.01 wt. %,
• optionally one or more elements selected from the group consisting of:
• (Cr:
• up to 0.25 wt. %, Mo:
• up to 0.10 wt. %, V:
• up to 0.30 wt. %, Cu:
• up to 0.20 wt. %, Ni:
• up to 0.50 wt. %, B:
• up to 0.005 wt. %),
• and balance Fe and inevitable impurities;
• and wherein the steel strip has a microstructure of:
• precipitation-strengthened acicular/bainitic ferrite and/or bainite,
• a MisOrientation Distribution (MOD) index of at least 0.85 at ¼-thickness,
• at most 5 vol. % of second-phase constituents, including any cementite, pearlite, martensite, and/or retained-austenite,
• an average grain size by number at ¼-thickness in the rolling direction and based on a grain tolerance angle of 15° (GSN15) of at most 2.0 μm,
• a total high-angle grain boundary length (ΣGBL15-65) at ¼-thickness of at least 1060 mm−1, and
• γ-fibre X-ray random intensity ratio of at least 27 as measured with XRD at ½-thickness;
• and wherein the steel strip has at least the following mechanical properties:
• a yield strength (Rp0.2) ranging from 600 to 820 MPa,
• an ultimate tensile strength (Rm) ranging between 730 and 950 MPa,
• a tensile elongation (A50) of at least 11%,
• a hole-expansion capacity (HEC) of at least 45%, and
• a work of fracture (WOF) of at least 100 J.