摘要
对镍基单晶高温合金在530℃的低周疲劳断口及断裂损伤机制进行研究。结果表明:在530℃时,单晶高温合金低周疲劳裂纹一般萌生于试样表面、亚表面或内部。亚表面存在铸造缺陷时裂纹从缺陷处起源。在大应变幅(>0.85%)条件下,合金在疲劳循环过程中表现出明显的循环硬化行为,应变幅低于0.85%时循环应力响应曲线基本趋于稳定。镍基单晶高温合金主要通过滑移产生变形,在530℃合金主要通过八面体滑移机制进行断裂,主滑移系为{111}<110>。分析断口特征可知,断口在源区附近未见明显塑性变形,稳定扩展区可见疲劳条带特征,快速扩展区在滑移台阶处存在大量交叉滑移带。通过电子背散射衍射分析发现,不同滑移面交界处的断口表面存在明显塑性变形,靠近断口表面的γ基体及立方γ’相变形严重。该温度下疲劳断口表面未见明显氧化特征。
The low-cycle fatigue performance and fracture damage mechanism of Ni-based single crystal superalloy were investigated at 530℃.Results show that at 530℃,the fatigue crack of the single crystal superalloy generally appears on the surface,sub-surface or inside of the sample.When there are casting defects on the sub-surface,fatigue crack will arise preferentially from the defects.Under the condition of large strain amplitude(>0.85%),the alloy shows obvious cyclic hardening behavior during the fatigue cycle,and the cyclic stress response curve tends to be stable when the strain amplitude is lower than 0.85%.The plastic deformation of Nibased single crystal superalloy is mainly proceeded by slip.At 530℃,the fracture of single crystal superalloy is mainly caused by octahedral slip mechanism,and the main slip system is{111}<110>.According to the sectional structure characteristics of the fracture,no obvious plastic deformation occurs near the source area.The characteristic of fatigue striation can be seen in the stable extension of the crack,and a lot of cross slip bands exist at the slip step in the rapid crack extension stage.By electron backscattered diffraction analysis,there are obvious plastic deformation on the fracture surface at the junction of different slip planes,and theγmatrix and cubicγ'phase near the fracture surface are seriously distorted.No obvious oxidation is observed on the surface of fatigue fracture at 530℃.
作者
张金刚
陈星
李振
田福政
刘新灵
Zhang Jingang;Chen Xing;Li Zhen;Tian Fuzheng;Liu Xinling(Failure Analysis Center of Aero Engine Corporation of China,AECC Beijing Institute of Aeronautical Materials,Beijing 100095,China;Beijing Key Laboratory of Aeronautical Materials Testing and Evaluation,Beijing 100095,China)
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2023年第6期1985-1993,共9页
Rare Metal Materials and Engineering
基金
National Science and Technology Major Project(J2019-Ⅵ-0022-0138)。
关键词
单晶高温合金
低周疲劳
八面体滑移
循环硬化
single crystal superalloy
low cycle fatigue
octahedral slip
cyclic hardening
