Weldability criteria for mash seam tailored blank welds in ultralow carbon steel applied to automotive bodies

摘要

Mash seam (MS) tailored blank (TB) welding is a production method for blanks involving welding together blanks of different material, thickness, and coating and is an attractive method for manufacturing car bodies because it leads to lighter parts, and can save cost and time in manufacture. However, quantified criteria to evaluate the quality of TB welds have not been developed. In the present work, the failure height ratio (FHR) was introduced to assess the weldability of MS welds, and the applicability of the FHR was confirmed via actual auto body forming and forming limit diagram tests. Furthermore, a new parameter, namely, a heat number based on the heat input calculated according to Q=I2Rt, was proposed and assessed. It was found that this heat number could be used to evaluate the soundness of MS welds.