Project nominated for Innovation of the Year Steelie Award 2022
Taking advantage of the unique lineup of CSP (flexible in width and thickness) technology, a novel high strength high formable sheet steel has been developed with very low-carbon lean alloying using an innovative fine-grained single-phase ferritic microstructure development strengthened with TiC nano precipitates.
The sheet steel is produced using a lean C-Mn-Ti alloy design using scrap in EAF and continuously cast, and hot rolled, followed by cold rolling and batch annealing at the lowest temperature (600-650°C) to optimise full recrystallisation of ferrite grains and retaining nano precipitates of TiC developed during hot rolling.
A Fully ferritic matrix thus develops strength from fine ferrite grains and nano-precipitation and offers the highest formability attributes as measured by hole expansion ratio (80-110%) and forming limit strains.
Tensile strengths similar to dual-phase 590 steel are achieved with formability properties far exceeding that of DP590 steels or any steels with similar strength.
The sheet steel also offers superior yield strengths much higher to that of conventional DP 590 steel, providing potential for automotive applications requiring high yield and high formability. A hole expansion ratio of 90% and above has been registered for a sheet thickness of 1.2mm.
The steel has been commercially produced and successfully used in critical autobody structural components such as seat side support, auto tubular applications and exhibited outstanding performance in complex stamping applications.