Crack growth thresholds in nickel-based superalloys under dwell-fatigue loading.

驻留疲劳载荷下镍基高温合金的裂纹扩展阈值。

• 批准号: 2718696
• 金额: --
• 依托单位: University of Birmingham
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2718696
• 关键词: Crack; growth; thresholds; nickel; based

Civil aviation requires the development of nickel-based superalloys to reduce life cycle cost. A higher operating temperature will generate a greater volume of thrust which increases efficiency. The development of RR 1073 is designed to increase the entry temperature to 800 degrees Celsius (from 727 degrees Celsius in previous alloy RR 1000). Resistance to dwell fatigue crack growth is now regarded as one of the primary parameters against which the discs have to survive to achieve an increase in service life. Discs are subjected to dwell fatigue at elevated temperature, which consists of long-term stress cycles for a hold time at maximum stress. A mechanism change from cyclic dependent transgranular fracture to time dependent intergranular fracture can occurs at longer dwell times. This project will study underlying micro-mechanisms of dwell crack growth and in particular will define conditions under which intergranular crack growth occurs in terms of crack growth threshold behaviour across a range of dwell times, temperatures and testing procedures. Insight into this phenomenon will be hugely beneficial to predictions of life in-service.

民用航空需要发展镍基高温合金以降低寿命周期成本。更高的工作温度将产生更大的推力，从而提高效率。RR 1073的开发旨在将入口温度提高到800摄氏度（以前的合金RR 1000为727摄氏度）。耐驻留疲劳裂纹扩展性现在被认为是一个主要参数，根据该参数，制动盘必须存活以实现使用寿命的增加。阀盘在高温下经受驻留疲劳，这包括在最大应力下保持一段时间的长期应力循环。在较长的保压时间下，发生了从周期相关穿晶断裂到时间相关沿晶断裂的机制转变。该项目将研究驻留裂纹扩展的基本微观机制，特别是将定义在裂纹扩展阈值行为方面发生晶间裂纹扩展的条件，包括驻留时间、温度和测试程序。对这一现象的深入了解将对预测服役寿命大有裨益。