PHYBAL-CHT - Short-time procedure for the determination of fatigue properties of steel

PHYBAL-CHT - 测定钢疲劳性能的短时程序

• 批准号: 252183314
• 负责人: Professor Dr.-Ing. Dietmar Eifler
• 金额: --
• 依托单位: Fachgebiet und Institut für Werkstoffkunde
• 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/252183314?language=en
• 关键词: PHYBAL; CHT; Short; time; procedure

Short-time and cost effective test methods are of major interest for the evaluation of fatigue properties of metallic materials, because conventional fatigue tests require cost consuming Woehler-experiments. To characterize the cyclic deformation behavior of metallic materials the relation of the plastic strain amplitude and the number of cycles is used and plotted in cyclic deformation curves.In the scope of the presented research project the plastic deformation behavior of steel will be described by a cyclic hardness test which shall be correlated with its cyclic deformation behavior. In the new approach PHYBAL-CHT (CHT = Cyclic Hardness Test), which is based on a cyclic hardness test, the plastic indentation-depth amplitude is determined as a function of the hardness measuring cycles. In analogy to the plastic strain amplitude the measured variables of the cyclic hardness test PHYBAL-CHT will be used to determine a plastic indentation strain amplitude. This procedure allows to describe quantitatively the cyclic hardening, as it is measured in cyclic deformation curves of normalized steels. In the submitted research project representative plastic indentation strain amplitudes shall be determined by the cyclic hardness test PHYBAL-CHT for 42CrMo4 (SAE 4140) in the normalized as well as three quenched and tempered states. The results shall be compared to cyclic deformation curves of conventional fatigue tests. It will be proved, that PHYBAL-CHT is suitable to describe the different cyclic deformation behavior of normalized or quenched and tempered steels.With this new method-approach the experimental effort can be reduced significantly compared to methods which are used to determine fatigue properties in a conventional manner. To prove the comparability between the results of PHYBAL-CHT and conventional fatigue tests, microstructural changes due to the applied loading will be investigated. Changes in the plastic deformed volume will be determined on step-by-step loaded PHYBAL-CHT specimens as well as specimens of conventional fatigue tests by two-dimensional micro hardness mappings, electron backscatter diffraction measurements and radiographic measurements of the full widths at half maximum intensity. To prove local microstructural changes by these methods, it is necessary, that the volume which is plastically deformed by the cyclic hardness test is sufficient in size. For this purpose, a test facility will be built to perform cyclic macro hardness measurements.

短期和成本效益的测试方法是评估金属材料疲劳性质的主要兴趣，因为常规疲劳测试需要耗费糟糕的成本。为了表征金属材料的环状变形行为，塑性应变振幅的关系和循环的数量被使用并绘制在循环变形曲线中。在提出的研究项目的范围中，钢的塑性变形行为将由循环硬度测试描述，该循环硬度测试将与其环状变形行为相关。在新方法中，基于环状硬度测试的phybal-cht（CHT =环状硬度测试），塑料压痕深度幅度是根据测量硬度测量循环的函数确定的。与塑性应变振幅相比，循环硬度测试的测量变量将用于确定塑性压痕应变幅度。该过程允许定量描述循环硬化，因为它以归一化钢的循环变形曲线进行了测量。在提交的研究项目中，代表性压痕应变幅度应由归一化的42CRMO4（SAE 4140）的循环硬度测试phybal-CHT确定，以及三个淬火和调节状态。结果应与常规疲劳测试的环状变形曲线进行比较。可以证明，植物性CHT适合描述归一化或淬火和回火钢的不同循环变形行为。与用于以常规方式确定疲劳性质的方法相比，这种新方法可以显着降低实验努力。为了证明Phybal-CHT和常规疲劳测试的结果之间的可比性，将研究由于施加的负载而引起的微结构变化。塑料变形体积的变化将在分步载荷植物phybal-CHT标本以及常规疲劳测试的标本上确定，通过二维微硬度映射，电子反向散射测量测量以及全半强度的全宽度测量值。为了证明这些方法的局部微观结构变化，有必要通过循环硬度测试对塑料变形的体积足够大小。为此，将建立一个测试设施以执行环状宏硬度测量。