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Prediction of the residual strength of corroded high-strength aluminum alloys under uniaxial loading by numerical simulations

单轴载荷下腐蚀高强铝合金残余强度的数值模拟预测

基本信息

批准号：
259373824
负责人：
Professor Dr.-Ing. Thomas Lampke
金额：
--
依托单位：
Professur Werkstoff- und Oberflächentechnik
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2014
资助国家：
德国
起止时间：
2013-12-31 至 2016-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/259373824?language=en
关键词：
Prediction residual strength corroded aluminum

项目摘要

High-strength aluminum alloys are used in a variety of components due to their high strength and good corrosion resistance. However, the corrosion resistance will fail if the passive layer is damaged, e.g. by chloride ions. Local corrosion phenomena (henceforth referred to as defects) and pitting corrosion occur as the damage is proceeding. This leads to a strength reduction of the material. The residual strength prediction under an uniaxial tensile loading based on the state of pitting corrosion is, thus far, not state of the art for high-strength aluminum alloys. The aim of this research project is the prediction of residual strength by a standard surface inspection. Two aluminum alloys (EN AW-2xxx and EN AW-7xxx) are carried out to transfer existing prediction models for steels to the high-strength aluminum alloys. The existing models will be improved by observing the morphology and distribution of the occurring defects. Corrosion tests at different conditions are realized to develop the model. The gained pitting corrosion will be quantified for each sample by using parameters to describe the shape and the distribution of the defects. The characterization of the defects will be non-destructive using a micro-optical 3D pattern surface measuring device. Subsequent FE-simulations of tensile tests are executed to attain analytical relations between the defect shape, distribution and residual strength. This will be achieved by means of a regression analysis. Additionally, stress analyses are performed to discuss critical defect shapes and distributions. This will be implemented by weighting factors. Finally, the residual strength model is obtained by the analytical relations and the weighting factors. The independent material reduction factor will be calculated by relating the calculated strength of the current damage state to the strength of the non-corroded material. Thus, the model to predict the residual strength can be applied to further aluminum alloys.

高强度铝合金由于其高强度和良好的耐腐蚀性而用于各种部件。然而，如果钝化层被损坏，例如被氯离子损坏，则耐腐蚀性将失效。局部腐蚀现象（以下称为缺陷）和点蚀随着损坏的进行而发生。这导致材料的强度降低。基于点蚀状态的单轴拉伸载荷下的剩余强度预测，迄今为止，还不是高强度铝合金的最新技术。本研究项目的目的是通过标准表面检测预测剩余强度。两种铝合金（EN AW-2xxx和EN AW-7 xxx）进行了现有的预测模型的钢的高强度铝合金。通过观察缺陷的形态和分布，改进现有的模型。通过不同条件下的腐蚀试验建立了腐蚀模型。通过使用参数描述缺陷的形状和分布，对每个样品的点蚀进行量化。缺陷的表征将是非破坏性的，使用微光学3D图案表面测量装置。随后的有限元模拟拉伸试验，以获得分析之间的关系，缺陷的形状，分布和剩余强度。这将通过回归分析来实现。此外，进行应力分析，讨论关键缺陷的形状和分布。这将通过加权系数来实现。最后，利用解析关系式和权重因子得到了剩余强度模型。通过将当前损坏状态的计算强度与未腐蚀材料的强度相关联，计算独立材料折减系数。因此，预测剩余强度的模型可以应用于进一步的铝合金。