Effect of microstructural and processing parameters on the fatigue properties of severely deformed iron

显微组织和加工参数对严重变形铁疲劳性能的影响

• 批准号: 242435020
• 负责人: Dr.-Ing. Enrico Bruder
• 金额: --
• 依托单位: Fachgebiet Physikalische Metallkunde
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2013
• 资助国家: 德国
• 起止时间: 2012-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/242435020?language=en
• 关键词: Effect; microstructural; processing; parameters; fatigue

In times of constantly rising raw material and energy costs, the aspect of resource efficiency is of growing importance for both production and application of products. A possible approach to face this challenge is to improve the crucial properties of materials which are most relevant for their applications. In the field of metallic structural materials the fatigue properties are fundamental for a wide range of applications. A promising method to increase both static and cyclic strength of metal is the grain refinement by Severe Plastic Deformation (SPD) processes. However, for these processes there is only little knowledge on the implications of processing parameters (and the resulting microstructures) on the fatigue properties and especially the damage mechanisms under cyclic loading. This lack of knowledge is the impetus for the present research project which shall contribute to the basic understanding of these correlations by fundamental investigations on pure iron as a model material. The project not only focuses on ultrafine grained (UFG) microstructures but also on severely deformed states with strains in the range of 1 to 4. Such deformed states can be regarded as a precursor to UFG structures and require significantly lower manufacturing costs.The project concentrates on the Identification of the dominant damage mechanisms above 10^4 cycles and their correlation with certain features of the severely deformed microstructure and premature damage caused by the SPD processing. For this purpose processing and microstructural parameters will be systematically varied to investigate their effect on the dominating damage mechanism as well as on the cyclic strength. Through the variation of the prestrain in the range of 1 to 4, the potential of precursors states as a cost-efficient alternative to UFG materials will be evaluated. Furthermore, UFG microstructures with a prestrain above 6 will be generated with varying aspect ratio and varying damage relevant processing parameters such as strain rate and hydrostatic stress. These will be used to investigate the impact of the effective glide length in elongated structures and relevance of premature damage from the SPD processing on the fatigue properties and their anisotropy.

在原材料和能源成本不断上升的时代，资源效率对于产品的生产和应用越来越重要。应对这一挑战的一种可能方法是改善与其应用最相关的材料的关键性能。在金属结构材料领域，疲劳性能是广泛应用的基础。通过剧烈塑性变形（SPD）工艺进行晶粒细化是提高金属静态和循环强度的一种有前途的方法。然而，对于这些过程中，只有很少的知识的影响的工艺参数（和由此产生的微观结构）的疲劳性能，特别是在循环载荷下的损伤机制。这种知识的缺乏是本研究项目的动力，该项目将有助于通过对纯铁作为模型材料的基本研究来基本了解这些相关性。该项目不仅关注超细晶（UFG）微观结构，还关注应变范围为1至4的严重变形状态。这种变形状态可以被看作是UFG结构的先驱，并且需要显著降低的制造成本。该项目集中于识别10^4次循环以上的主要损伤机制，以及它们与严重变形微观结构的某些特征和SPD处理引起的过早损伤的相关性。为此，将系统地改变工艺和微观结构参数，以研究它们对主要损伤机制以及循环强度的影响。通过在1至4的范围内的预应变的变化，前体状态作为UFG材料的成本效益的替代品的潜力将被评估。此外，具有高于6的预应变的UFG微结构将随着变化的纵横比和变化的损伤相关的工艺参数（例如应变速率和静水应力）而产生。这些将被用来调查的有效滑移长度的影响，在细长结构和相关的过早损坏的SPD处理的疲劳性能和它们的各向异性。

项目成果

Influence of equal channel angular pressing on high cycle fatigue behavior of ultrafine-grained iron: Role of anisotropy

• DOI: 10.1016/j.msea.2017.11.075
• 发表时间: 2018-01
• 期刊: Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
• 影响因子: 6.4
• 作者: E. Bruder;Chandanraj Gangaraju;R. Lapovok