Deformation mechanisms and fatigue crack initiation in single crystal nickel superalloys

单晶镍高温合金的变形机制和疲劳裂纹萌生

• 批准号: 2275727
• 金额: --
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2275727
• 关键词: Deformation; mechanisms; fatigue; crack; initiation

Despite high safety factors in the design of nickel superalloy components in gas turbine engines, part failure and material degradation still ultimately occur. Fatigue failure remains the most common cause of failure for these components, and exists in the forms of mechanical, thermomechanical and creep; cyclic stress and strain leads to localised plastic deformation at regions of high stress concentration, around complex geometries, pores, and inclusions, which results in the initiation of fatigue cracks. A greater understating of this process will lead to more accurate component lifing predictions, enabling safer operation and a reduction in cost.Notched single crystal nickel samples have been tested under fatigue loading to determine fatigue life; using material data, along with crystal plasticity finite element (CPFE) modelling, complex models have been generated to estimate fatigue lives using damage criteria. Detailed models of the microstructure of these alloys have been created using representative volume elements (RVE) in order to extract slip strengths of different slip systems present in the gamma/gamma' microstructure, creating a two-phase representative model. These models will be used to simulate fatigue loading of notched single crystal samples to determine any for mechanistic drivers for fatigue crack initiation.

尽管在燃气轮机发动机中镍超合金组件的设计方面具有很高的安全因子，但最终仍会发生零件故障和材料降解。疲劳失败仍然是这些组件失败的最常见原因，并以机械，热机械和蠕变的形式存在。循环应力和应变会导致高应力浓度，复杂几何形状，毛孔和夹杂物周围的局部塑性变形，从而导致疲劳裂纹的启动。对此过程的低估将导致更准确的组件效率预测，使其更安全的操作和成本降低。已在疲劳载荷下测试了注释的单晶镍样品，以确定疲劳寿命；使用材料数据，以及晶体可塑性有限元（CPFE）建模，已经生成复杂模型，以使用损害标准估算疲劳生活。这些合金的微观结构的详细模型是使用代表体积元素（RVE）创建的，以提取伽玛/伽马的微结构中存在的不同滑移系统的滑动强度，从​​而创建了一个两相代表模型。这些模型将用于模拟缺口单晶样品的疲劳负荷，以确定机械驱动因素的疲劳裂纹启动。