Manufacturing challenges in stamping and fabrication of components from advanced high strength steel

Advanced high strength steels (AHSS), including dual phase, TRIP and martensitic grades, are being applied to new vehicle programs because of their contribution to efficient, mass-optimized vehicle structures. Improvements to the energy absorption, durability and structural strength of body structures result from increased usage of advanced high strength steels. However, many manufacturing challenges must be addressed to apply these materials successfully. Forming is a unique challenge, as these materials have more formability than conventional high strength steels. Successful stamping of AHSS requires increased press force and energy. This influences selection of forming processes and die materials. Engineers must also contend with increased springback in the parts. Improvements in simulation technology are required to predict springback successfully. Simulation technology is also required to predict stress-based failures in addition to the typical strain-based failures commonly seen in stamping processes. Joining these materials can also be challenging, as their properties depend on higher levels of alloying than is typically used in automotive body structure materials. The multiphase microstructures are sensitive to the heat input of welding processes. Higher hardenability leads to additional complexity in spot welding processes as well. This paper will discuss these manufacturing challenges, and some of the lessons from these experiences, as AHSS become more widely used. (AU)