Ductibor® 500-AS is a hot-stamping steel that has been designed to introduce local ductile regions within hot-stamped tailor-welded blanks (TWBs) used for energy-absorbing sections of automotive structures. This study investigates the flow and fracture behavior of a range of the microstructures of this alloy, corresponding to mostly ferritic (∼ 96% ferrite plus 4% martensite), intermediate ferritic + martensitic (∼ 57% ferrite plus 43% martensite), and mostly martensitic (∼ 10% ferrite plus 90% martensite), obtained by applying various quench rates after austenitization. A series of mechanical tests in various stress states, ranging from simple shear to biaxial tension, was performed to characterize fracture for the developed microstructures. A mean-field homogenization (MFH) technique was then used to predict the flow and fracture response as a function of the microstructure. An MFH scheme designated as the interpolative Samadian-Butcher-Worswick 1 (INSBW1) within the first-order secant-based linearization method was considered to predict the macroscopic hardening behavior of the ferritic-martensitic microstructures. In the MFH modelling, the flow response of the ferritic and martensitic phases was modelled based on a dislocation-based hardening model, taking into account the chemical composition, carbon partitioning between phases, and dislocation generation and annihilation. Damage accumulation and the onset of fracture were predicted using a phenomenological damage indicator defined within each constituent phase given their calculated fracture loci and instantaneous stress and strain states. The experimental results showed that the mostly-martensitic microstructure had the lowest ductility and highest strength, and ductility and strength increased and decreased, respectively, as the martensite volume fraction in the microstructure decreased. The predicted flow curves and fracture strains as well as the fracture-limit curves for all of the microstructures agreed well with the measured data and interpolated Modified-Mohr-Coulomb (MMC) fracture loci.

Ductibor® 500-AS 是一种热冲压钢，旨在在用于汽车结构吸能部分的热冲压拼焊板 (TWB) 内引入局部延展性区域。本研究调查了该合金的一系列显微组织的流动和断裂行为，对应于主要是铁素体（约 96% 铁素体加 4% 马氏体）、中间铁素体 + 马氏体（约 57% 铁素体加 43% 马氏体），以及大部分马氏体（约 10% 铁素体加 90% 马氏体），通过在奥氏体化后应用不同的淬火速率获得。进行了一系列不同应力状态下的机械测试，范围从简单剪切到双轴拉伸，以表征开发的微观结构的断裂。然后使用平均场均匀化 (MFH) 技术来预测作为微观结构函数的流动和断裂响应。在基于一阶割线的线性化方法中指定为插值 Samadian-Butcher-Worswick 1 (INSBW1) 的 MFH 方案被认为是预测铁素体-马氏体显微组织的宏观硬化行为。在 MFH 建模中，铁素体和马氏体相的流动响应基于基于位错的硬化模型进行建模，同时考虑了化学成分、相之间的碳分配以及位错的生成和湮灭。根据计算的断裂情况，使用在每个组成阶段中定义的现象学损坏指标来预测损坏累积和断裂的发生 在基于一阶割线的线性化方法中指定为插值 Samadian-Butcher-Worswick 1 (INSBW1) 的 MFH 方案被认为是预测铁素体-马氏体显微组织的宏观硬化行为。在 MFH 建模中，铁素体和马氏体相的流动响应基于基于位错的硬化模型进行建模，同时考虑了化学成分、相之间的碳分配以及位错的生成和湮灭。根据计算的断裂情况，使用在每个组成阶段中定义的现象学损坏指标来预测损坏累积和断裂的发生 在基于一阶割线的线性化方法中指定为插值 Samadian-Butcher-Worswick 1 (INSBW1) 的 MFH 方案被认为是预测铁素体-马氏体显微组织的宏观硬化行为。在 MFH 建模中，铁素体和马氏体相的流动响应基于基于位错的硬化模型进行建模，同时考虑了化学成分、相之间的碳分配以及位错的生成和湮灭。根据计算的断裂情况，使用在每个组成阶段中定义的现象学损坏指标来预测损坏累积和断裂的发生 铁素体和马氏体相的流动响应基于基于位错的硬化模型进行建模，同时考虑了化学成分、相之间的碳分配以及位错的生成和湮灭。根据计算的断裂情况，使用在每个组成阶段中定义的现象学损坏指标来预测损坏累积和断裂的发生 铁素体和马氏体相的流动响应基于基于位错的硬化模型进行建模，同时考虑了化学成分、相之间的碳分配以及位错的生成和湮灭。根据计算的断裂情况，使用在每个组成阶段中定义的现象学损坏指标来预测损坏累积和断裂的发生轨迹和瞬时应力和应变状态。实验结果表明，主要为马氏体的组织具有最低的延展性和最高的强度，随着组织中马氏体体积分数的减少，延展性和强度分别增加和减少。所有微观结构的预测流动曲线和断裂应变以及断裂极限曲线与测量数据和内插修正莫尔-库仑 (MMC) 断裂轨迹非常吻合。