Abstract The advanced high strength steels (AHSS) are well recognized for their high-strength-to-weight ratio combined with good shock absorption properties. Moreover, these steels are also known for their complex forming and fracture characteristics. This study is aimed at investigating the fracture behavior of AHSS sheets under the influence of an equal-biaxial state of stress. The work was conducted on two important AHSS sheets – (i) DP980 and (ii) TRIP1180. A hydraulic bulge test was performed to cause the fracture under biaxial loading condition. The strains near the pole of the bulge specimens were measured using the digital image correlation technique. A detailed micro- and macro-scale characterization was performed to examine the fracture aspects of both sheets. The results clearly indicated the occurrence of shear localization during fracture. Moreover, the likely sources of micro-crack initiation were also revealed. Apart from fracture characterization, a comprehensive finite element study was done using appropriate constitutive equations. Finally, a simple fracture criterion was applied to predict the onset of fracture for both steels.

中文翻译：

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先进高强钢水压胀形试验断裂特性研究

摘要 先进的高强度钢（AHSS）因其高强度重量比和良好的减震性能而广为人知。此外，这些钢还因其复杂的成形和断裂特性而闻名。本研究旨在研究在等双轴应力状态影响下高强钢板材的断裂行为。这项工作是在两个重要的 AHSS 表上进行的——(i) DP980 和 (ii) TRIP1180。在双轴加载条件下进行了液压膨胀试验以引起断裂。使用数字图像相关技术测量凸起试样极点附近的应变。进行了详细的微观和宏观尺度表征，以检查两种板材的断裂方面。结果清楚地表明在断裂过程中发生了剪切局部化。此外，还揭示了微裂纹萌生的可能来源。除了裂缝表征外，还使用适当的本构方程进行了全面的有限元研究。最后，应用简单的断裂标准来预测两种钢的断裂开始。