Formability investigation of two advanced high-strength steels: conventional versus high total elongation 780 MPa grades

Advanced High-Strength Steels are widely employed in the automotive industry to reduce vehicle mass without compromising structural integrity and safety requirements.However, the limited formability of these materials imposes significant constraints on forming processes.This study compares the formability of an AHSS with a minimum tensile strength of 780 MPa, industrially produced through two distinct thermomechanical processing routes: conventional and optimized with high total elongation.The samples were characterized in terms of microstructure, mechanical behavior and formability.The results indicate that the optimized condition, featuring greater homogeneity, higher volume fractions of bainite and retained austenite, and increased elongation, exhibited a 20% increase in FLC 0 and 55% improvement in edge stretchability, demonstrating substantial enhancements in both global and local formability.Numerical simulation of the stamping process showed a significant reduction in failure due to fracture.These findings were validated at the industrial scale, where the rework rate of stamped parts was reduced from 30-40% to nearly zero.Such results reinforce the importance of microstructural control as a key tool to enable the application of AHSS materials in automotive components with complex geometries.