Factors Influencing Dual Phase Steel Flanging Limit Punching

Based on pre-punching to hot rolled martensitic and bainitic dual phase steels with similar elongation and work hardening index (n), as well as similar thickness and hole expansion test using taper die, analysis of the hole expansion rate indicated significant difference in their flanging performance. The results indicated that mechanical property was not the only major factor that influenced flanging. Further analysis of the hole border microstructure, work hardening condition, and fracture property showed that the fracture property of sheets was the major factor that influenced flanging performance.