Advanced high-strength steel (AHSS) is composed of complex steel chemistries and thermomechanical properties that improve strength and ductility. It is this improved strength that allows the use of thinner (and therefore lighter) gauges and so addresses some of the challenges of lightweighting vehicles because it can reduce mass while maintaining strength to meet NHTSA safety standards (see CAFE Standards, NHTSA, and AHSS).
This higher yield strength of AHSS presents challenges to metal stampers in terms of formability and a greater tendency to retain coil set. These materials also have wider tolerances on their yield strength, yet narrower tolerances between their yield and tensile strength. Therefore, the force required to yield and form the material cannot be excessive because of the potential to take the material past its tensile strength.
Stamping AHSS typically requires increased forces, which can adversely affect tooling as well as amplify vibrations that can potentially damage the dies and even the press. Over the past decade, task forces have been formed to develop guidelines that help stampers gain the knowledge they need to help deal with these challenges in terms of the die and stamping process.
However, to successfully process AHSS, stampers need to look at every aspect of the stamping line, including the press feeding operations and, in particular, the straightening equipment and process.
Read the full article at: STAMPING JOURNAL