Extensive interface exfoliation (flaking) mechanism occurring in the bead-slide region was investigated using numerical and experimental methods. For high reliability, the material constants of dynamic loading were obtained by high-strain-rate tensile tests and applied to simulation modeling for hat channel drawing with a bead test (hat-bead test). Accordingly, a highly reliable model was developed, the results of which matched well with those of experiments. The damage as a function of the stress and strain in a specimen was maximized by vertical drawing after bending and was concentrated on the surface, indicating severe tensile strain localized on the surface. Numerous fragments of large size were correspondingly found at the bottom of the vertical wall. In addition, the damage trend was nearly identical in each region in the hat-bead experiment. Moreover, the features of the fragments in extensive flaking in the hat-bead test were very similar to those in practical press-forming, indicating that the flaking was generated by the same mechanism. Consequently, the bead-slide region, severe surface damage due to localized tensile strain occurring during vertical bending is the main cause of extensive flaking.

使用数值和实验方法研究了在珠-滑动区域中发生的广泛的界面剥落（剥落）机理。为了获得较高的可靠性，通过高应变率拉伸测试获得了动态载荷的材料常数，并将其应用于带有珠子测试（帽珠测试）的帽子通道拉伸的仿真模型。因此，开发了高度可靠的模型，其结果与实验结果非常吻合。弯曲后通过垂直拉伸将样品中应力与应变的函数关系最大化，并将其集中在表面上，这表明表面上存在严重的拉伸应变。在垂直壁的底部相应地发现了许多大尺寸的碎片。此外，在帽子珠实验中，每个区域的损坏趋势几乎相同。此外，在帽珠试验中，大量剥落中的碎片特征与实际压制成型中的碎片特征非常相似，这表明剥落是通过相同的机理产生的。因此，在垂直弯曲过程中由于局部拉伸应变而导致的胎圈滑动区域，严重的表面损坏是造成大量剥落的主要原因。