A Markov-Chain Model for Intergranular Stress Corrosion Cracking

本研究基于多晶微观结构的可测量特征，建立了一种新的金属晶间应力腐蚀开裂模型。在该模型中，裂纹被看作是通过晶界网络进行的，当裂纹渗透到材料中时就会导致破坏。该项目的第一阶段将是比较界面能的各种模型。该分析将主要是对从开裂样品中获得的数据进行统计分析，然后对现有的界面能模型进行比较和修改。接下来，该模型将用于比较不同微观结构的抗裂性。要测试的微观结构将包括随机纹理，通过退火数值模型模拟的纹理，以及由卡内基梅隆大学布伦特亚当斯研究组测量的实际材料的纹理。模拟加工模型的纹理结果将预测材料加工对材料性能的净影响。许多工程材料（例如，金属和金属合金）的寿命受到应力腐蚀开裂现象的严重限制。当材料受到拉应力和腐蚀元素的共同作用时，这种类型的失效就会发生，导致裂纹在材料中传播并导致其破裂。提出的研究的主要目的是建立和分析一种新的晶间应力腐蚀裂纹模型。该模型用于预测金属和金属合金裂纹的扩展，它的独特之处在于它包含了来自材料的可测量的微观结构信息。由于应力腐蚀开裂在某些材料中是一种常见的灾难性现象，因此对于工程师来说，通过测量微观结构和使用模型来估计材料的开裂敏感性是非常宝贵的。此外，如果可以将给定的加工技术与所得的微观结构联系起来，则可以使用该模型来规定可以增强抗应力腐蚀开裂的工艺。

Olson 9704471 The proposed research develops a new model of intergranular stress corrosion cracking of metals, based on measurable features of the polycrystalline microstructure. In the model, the crack is viewed as proceeding through a network of grain boundaries, causing failure when the crack percolates through the material. The first phase of this project will be to compare various models for interface energy. This analysis will largely be a statistical analysis of data obtained from cracked samples, followed by a comparison and modification of the existing interfacial energy models. Next, the model will be used to compare the resistance to cracking of various microstructures. The microstructures to be tested will include random textures, textures simulated through numerical models of annealing, and textures from actual materials measured by Brent Adams' experimental group at Carnegie Mellon University. The results for textures from simulated processing models will predict the net effect of material processing on material performance. The lifetime of many engineering materials (for example, metals and metal alloys) is seriously limited by their susceptibility to the phenomenon called stress corrosion cracking. This type of failure occurs when the material is subject to a combination of tensile stress and a corrosive element, leading to a crack which propagates through the material and causes it to break. The main objective of the proposed research is to develop and analyze a new model of intergranular stress corrosion cracking. This model is used to predict the growth of cracks in metals and metal alloys, and it is unique in that it incorporates measurable microstructural information from the material. Because stress corrosion cracking is a common and catastrophic phenomenon in certain materials, it would be invaluable for engineers to be able to estimate a material's susceptibility to cracking by measuring microstructure and u sing the model. In addition, if one can correlate given processing techniques with the resulting microstructures, one could then use this model to prescribe processes which would enhance resistance to stress corrosion cracking.