Environmentally Assisted Cracking (EAC) of 7xxx series aluminium alloys involves interactions between multiple physical phenomena, which ultimately influence the in-service life of critical components. In this work, we present a new model to study EAC in 7xxx series alloys, which is implemented in the multiphysics simulation framework, DAMASK. The chemo-mechanical model couples crack tip hydrogen generation, resulting from surface oxidation, and transport, with crystal-plasticity-governed intergranular crack propagation, through the microstructural trapping of hydrogen at dislocations, grain boundaries (GB), and crack tip stress fields. Large-scale simulations with realistic grain structures have been performed to provide novel insight into the dominant rate-controlling processes associated with intergranular EAC in 7xxx series aluminium alloys. The model was able to reproduce experimentally measured crack velocities under different loading conditions. Parametric studies indicate that, in addition to the GB network morphology, the crack growth rate was controlled by hydrogen generation at the crack tip with long-range diffusion having negligible influence. Additionally, the total hydrogen generated through crack tip oxidation appears to be more significant than the peak generation rate.

中文翻译：

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使用耦合化学-机械相场损伤模型模拟 Al 合金中的氢控裂纹扩展动力学


7xxx 系列铝合金的环境辅助开裂 （EAC） 涉及多种物理现象之间的相互作用，最终影响关键部件的使用寿命。在这项工作中，我们提出了一个研究 7xxx 系列合金中 EAC 的新模型，该模型在多物理场仿真框架 DAMASK 中实现。化学力学模型通过氢在位错、晶界 （GB） 和裂纹尖端应力场的微观结构捕获，将表面氧化产生的裂纹尖端氢的产生和传输与晶体塑性控制的晶间裂纹扩展耦合在一起。已经进行了具有真实晶粒结构的大规模模拟，为与 7xxx 系列铝合金中的晶间 EAC 相关的主要速率控制过程提供了新的见解。该模型能够重现不同载荷条件下实验测得的裂纹速度。参数研究表明，除了 GB 网络形态外，裂纹扩展速率还受到裂纹尖端氢生成的影响，而长距离扩散的影响可以忽略不计。此外，通过裂纹尖端氧化产生的总氢似乎比峰值生成速率更重要。