Experimental and Numerical Analysis of Work Hardening Effects in Single- and Polycrystals during Cyclic Loading (Bauschinger Effect)

循环加载过程中单晶和多晶的加工硬化效应（包辛格效应）的实验和数值分析

• 批准号: 389025087
• 负责人: Professor Dr.-Ing. Ulrich Krupp
• 金额: --
• 依托单位: Fakultät Maschinenbau und Verfahrenstechnik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/389025087?language=en
• 关键词: Experimental; Numerical; Analysis; Work; Hardening

In practice, the service life of cyclically loaded metallic components is limited by fatigue damage of the alloys applied. Partly irreversibility of the cyclic plastic deformation leads to strain localization, crack initiation and propagation and eventually, to fracture. Especially, unfavorable crystallographic orientations of grains and grain boundaries cause additional stress concentration, and therefore, local plasticity may exhibit even at deformations that are macroscopically elastic. Here, the Bauschinger effect is of particular significance, since it describes load-orientation-dependent strain hardening. By means of micro-indentation and micro-bending experiments as well as tension-compression tests applied to a variety of heat treatments, where the deformation mechanisms will be identified in detail by microstructural analysis (using scanning electron microscopy, incl. EBSD and FIB, and transmission electron microscopy), the proposed project will lead to the development of single crystal and poly crystal material models, that allow for explicit implementation of the Bauschinger effect in the Finite Element method. Verification experiments on two technical important alloys, the duplex steel and Ni-based superalloy 718, will show the potentials and the limits of the proposed models.

实际上，循环负载金属部件的使用寿命受到所用合金的疲劳损伤的限制。循环塑性变形的部分不可逆性导致应变局部化、裂纹萌生和扩展，并最终导致断裂。特别是，晶粒和晶界的不利晶体取向会导致额外的应力集中，因此，即使在宏观弹性变形的情况下，也可能表现出局部塑性。在这里，包辛格效应特别重要，因为它描述了与载荷方向相关的应变硬化。通过微压痕和微弯曲实验以及应用于各种热处理的拉伸压缩试验，通过微观结构分析（使用扫描电子显微镜，包括EBSD和FIB）详细确定变形机制，和透射电子显微镜），拟议的项目将导致单晶和多晶材料模型的开发，从而允许在有限元方法中明确实现包辛格效应。对两种重要技术合金（双相钢和镍基高温合金 718）的验证实验将显示所提出模型的潜力和局限性。