Abstract This paper presents a physically-based cyclic viscoplasticity model to capture the influence of welding-induced microstructural transformation on the fatigue response of the bainitic high-strength low-alloy steel, X100Q. The model incorporates the strengthening effects of dislocations, microstructural boundaries and precipitates, and the softening effects of microstructural degradation and early-life fatigue damage on yield strength and nonlinear cyclic-plastic response. The model is applied to predict the constitutive responses of X100Q parent material, physically-simulated intercritical heat affected zone (HAZ) and fine-grained HAZ, based on differences in bainitic hierarchical microstructure between the materials. A refined bainitic block structure is shown to be the primary microstructural feature contributing to monotonic and cyclic strength in the materials, whereas dislocation annihilation and the concomitant coarsening of the bainitic lath structure with cyclic-plastic deformation leads to cyclic softening behaviour.

中文翻译：

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焊接引起的显微组织转变对 x100q 贝氏体钢循环塑性和低周疲劳影响的位错力学本构模型

摘要 本文提出了一种基于物理的循环粘塑性模型，以捕捉焊接引起的显微组织转变对贝氏体高强度低合金钢 X100Q 疲劳响应的影响。该模型结合了位错、微观结构边界和析出物的强化效应，以及微观结构退化和早期疲劳损伤对屈服强度和非线性循环塑性响应的软化效应。该模型用于预测 X100Q 母材、物理模拟临界热影响区 (HAZ) 和细晶粒 HAZ 的本构响应，基于材料之间贝氏体分级微观结构的差异。