抄録
The formability and fatigue performance of welded advanced high strength steel sheets were studied at the viewpoints of industrial tailored blank application. In order to obtain material requirements for the formability of tailored blanks, five different 590MPa steels were evaluated with laser welding and plasma arc welding. In addition, appropriate welding parameters were investigated. The material property of base metal for improving the formability of laser welded steel sheets was high elongation. The material requirement for plasma arc welding was low weld hardness. Low carbon content was a favorable composition for plasma arc welding. Welding speed was important for the formability of laser welded ultra high strength steel sheets. Low welding speed should be avoided to prevent a softening in HAZ. The clamping position of jig for plasma arc welding could affect the formability, because of the changing a cooling effect by the clamping jig. The fatigue strength of laser and arc welded joints using AHSS were higher than that of mash seam welded joints.
