Influence of ultrasound on the strain hardening behaviour of metallic materials

超声波对金属材料应变硬化行为的影响

• 批准号: 405225776
• 负责人: Professor Dr. Eberhard Kerscher
• 金额: --
• 依托单位: Arbeitsgruppe Werkstoffprüfung (AWP)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/405225776?language=en
• 关键词: Influence; ultrasound; strain; hardening; behaviour

Ultrasound is used to improve and optimize the results of many manufacturing processes. Current ultrasound applications are often based on the results of work done by Blaha and Langenecker in the 1960s. They showed that the flow stress of metallic materials can be reduced significantly if ultrasound is superimposed during a tensile test. Additionally, the application of ultrasound can in some materials lead to temporary or permanent hardening.The reason for this so-called acoustic softening and hardening is still not completely understood from a materials science point of view. While there are several publications dealing with acoustic softening and attempting to explain the underlying mechanisms there are just a few publications dealing with acoustic hardening. In all those works acoustic softening and hardening are reported mainly for hexagonal (zinc) or face-centred cubic (aluminium) metals, although many technical applications deal mostly with the ultrasonic supported manufacturing processes of steels.Within the current proposal systematic investigations shall be carried out to clarify the circumstances, at which acoustic softening and hardening occurs in ferritic, body-centred cubic and austenitic, face-centred cubic steels, for the first time. Therefore, an experimental setup has to be built up to superimpose ultrasonic pulses at a defined moment for a restricted time during a classical compression test. These experiments will be carried out with the above mentioned steels to analyse how variations of the initial materials state, namely the initial dislocation density, and variations of the power and the duration of the ultrasonic pulses will influence the acoustic softening and hardening. Thereby, the mechanical materials response has to be measured during and after the ultrasonic pulses. In addition, the microstructural changes have to be characterised by light optical microscopy, electron microscopy, and by local indentation experiments.It is envisaged to finally derive a metal physical explanation has to be derived to explain the ultrasonic induced softening and hardening phenomena. This clarification of the acoustic effect is the main goal of the project and is planned to serve as basis for the application of the acoustic softening and hardening also in other metallic materials.

超声波用于改善和优化许多制造过程的结果。目前的超声波应用通常是基于Blaha和Langenecker在20世纪60年代所做的工作结果。他们表明，如果在拉伸试验中叠加超声波，金属材料的流动应力可以显著降低。此外，超声波在某些材料中的应用会导致暂时或永久硬化。从材料科学的角度来看，这种所谓的声学软化和硬化的原因仍然没有完全理解。虽然有一些出版物处理声学软化并试图解释潜在的机制，但只有少数出版物处理声学硬化。在所有这些工作中，声学软化和硬化主要用于六角形（锌）或面心立方（铝）金属，尽管许多技术应用主要涉及超声波支持钢的制造过程。在目前的建议中，应首次进行系统的调查，以澄清铁素体、体心立方钢和奥氏体、面心立方钢在声学软化和硬化时发生的情况。因此，必须建立一个实验装置，以便在经典压缩试验中在限定的时间内在限定的时刻叠加超声波脉冲。这些实验将用上述钢进行，以分析初始材料状态的变化，即初始位错密度，以及超声脉冲功率和持续时间的变化如何影响声软化和硬化。因此，必须在超声波脉冲期间和之后测量机械材料的响应。此外，微观结构的变化必须通过光学显微镜、电子显微镜和局部压痕实验来表征。设想最终推导出一种金属物理解释来解释超声诱发的软化和硬化现象。澄清声学效应是该项目的主要目标，并计划作为声学软化和硬化在其他金属材料中的应用的基础。