Abstract Cast pores are known to cause stress/strain concentrations, facilitating the initiation of fatigue cracks and shortening the fatigue lifetime of cast materials; however, it is an open question regarding how the deformation fields generated by different pores interact each other and evolve with fatigue loading. The present study addresses the local deformation behavior in cast-pore containing high manganese steel during fatigue loading investigated using single- and multi-pore finite-element models. These models take into account the actual size, shape and distribution of pores based on X-ray computed tomography images and consider the actual material properties of the steel, i.e. the high strain-hardening rate, cyclic hardening law and Bauschinger effect using a viscoplastic constitutive model within the framework of Chaboche model. The results demonstrate that the local stress, strain and hysteresis loop energy around an actual pore evolve progressively with fatigue loading, and reach as large as 2 to 4, 2.5 to 8.5 and 6 to 30 times their corresponding far-field values at high fatigue cycles. More importantly, two different effects, i.e. "umbrella-like stress shielding" and "overlapping stress amplifying", are identified in the presence of multiple pores, due to the deformation fields interactions between pores. And, which of the two effects takes place or predominates depends on the specific location of concern and the spatial distribution of pores. These findings may be extended to provide some new insight into the fatigue damage micromechanisms in various cast-pore containing materials and to help understand the scatters of their fatigue lifetime in terms of the local deformation fields around pores and their interactions.

中文翻译：

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铸造高锰钢气孔间循环变形场相互作用

摘要 众所周知，铸造气孔会引起应力/应变集中，促进疲劳裂纹的产生并缩短铸造材料的疲劳寿命；然而，关于不同孔隙产生的变形场如何相互作用并随疲劳载荷演变，这是一个悬而未决的问题。本研究使用单孔和多孔有限元模型研究疲劳载荷期间含铸造孔的高锰钢的局部变形行为。这些模型考虑了基于 X 射线计算机断层扫描图像的孔隙的实际尺寸、形状和分布，并考虑了钢的实际材料特性，即高应变硬化率、循环硬化规律和使用粘塑性本构的包辛格效应Chaboche 模型框架内的模型。结果表明，实际孔隙周围的局部应力、应变和磁滞回线能量随着疲劳载荷逐渐演变，在高疲劳循环下达到其相应远场值的 2 到 4 倍、2.5 到 8.5 倍和 6 到 30 倍. 更重要的是，由于孔隙之间的变形场相互作用，在存在多个孔隙的情况下确定了两种不同的效应，即“伞状应力屏蔽”和“重叠应力放大”。并且，这两种效应中的哪一种发生或占优势取决于关注的具体位置和孔隙的空间分布。