We present a new theoretical and numerical framework for modelling mechanically-assisted corrosion in elastic-plastic solids. Both pitting and stress corrosion cracking (SCC) can be captured, as well as the pit-to-crack transition. Localised corrosion is assumed to be dissolution-driven and a formulation grounded upon the film rupture-dissolution-repassivation mechanism is presented to incorporate the influence of film passivation. The model incorporates, for the first time, the role of mechanical straining as the electrochemical driving force, accelerating corrosion kinetics. The computational complexities associated with tracking the evolving metal-electrolyte interface are resolved by making use of a phase field paradigm, enabling an accurate approximation of complex SCC morphologies. The coupled electro-chemo-mechanical formulation is numerically implemented using the finite element method and an implicit time integration scheme; displacements, phase field order parameter and concentration are the primary variables. Five case studies of particular interest are addressed to showcase the predictive capabilities of the model, revealing an excellent agreement with analytical solutions and experimental measurements. By modelling these paradigmatic 2D and 3D boundary value problems we show that our formulation can capture: (i) the transition from activation-controlled corrosion to diffusion-controlled corrosion, (ii) the sensitivity of interface kinetics to mechanical stresses and strains, (iii) the role of film passivation in reducing corrosion rates, and (iv) the dependence of the stability of the passive film to local strain rates. The influence of these factors in driving the shape change of SCC defects, including the pit-to-crack transition, is a natural outcome of the model, laying the foundations for a mechanistic assessment of engineering materials and structures.
翻译:我们提出了一个新的理论和数字框架,用于在弹性塑料固体中模拟机械辅助的腐蚀。可以捕捉坑状和压力腐蚀裂缝(SCC),以及坑到裂缝的过渡。局部腐蚀假定是溶解驱动的,以电影断裂-分解-消化-消化机制为基础,提出一种配方,以纳入电影消化的影响。模型首次纳入了机械磨蚀作为电化学驱动力的作用,加速腐蚀动能。与跟踪不断演变的金属-电压裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂裂变变变变变变变变变变变变变变变变变变变变变变变。五个特别感兴趣的案例研究是展示模型的预测能力,揭示了分析性变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变的精确变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变,揭示的变变变变变变变变变变变变变变变变变,显示的变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变的变, 变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变变,变变变变变变变变变变变变变变变变变变变变变变变变变变变变变