IN792LC单晶高温合金长期热暴露下的蠕变性能退化
Degradation of creep properties in single crystal superalloy IN792LC during long-term thermal exposure
李石磊 1帅三三 1汪超 2何磊 2王江 1任忠鸣1
作者信息
- 1. 上海大学材料科学与工程学院,省部共建高品质特殊钢冶金与制备国家重点实验室,上海 200444
- 2. 上海电气燃气轮机有限公司,上海 200240
- 折叠
摘要
研究了 800℃条件下最长时间达到 3 000h的长期热暴露对IN792LC单晶高温合金显微组织演变及蠕变行为的影响.结果表明:长时间热暴露后,γ'相球化生长均匀分散在γ基体内,γ'相的粗化行为符合 Lifshitz-Slyozov-Wagner(LSW)模型.热暴露后一些不连续碳化物在γ/γ'共晶组织周围析出,但无拓扑密排相(TCP)生成.对长期热暴露后的合金进行了 760℃/662 MPa下蠕变断裂寿命测试,随着热暴露时间延长,由于组织退化,合金蠕变寿命降低,而断裂伸长率不断提高.当热暴露达到 3 000h时,合金蠕变断裂寿命降低 81.1%.合金蠕变寿命的减少主要由γ'相粗化、碳化物的退化以及柯肯达尔孔洞增大导致.分析发现在热暴露后共晶相周围MC碳化物分解形成的 M23C6 碳化物,空位在碳化物处塌陷聚集成微孔,加速了裂纹的萌生与拓展.此外,由于热暴露后合金蠕变过程中的位错网络被破坏,位错切入γ'相运动,从而进一步降低蠕变断裂寿命.研究结果为IN792LC单晶高温合金近服役温度条件下使用寿命预测提供了参考.
Abstract
The influence of long-term thermal exposure up to 3 000 h at 800℃on the microstructure evolution and creep behavior of the IN792 LC single crystal superalloy was investigated.The results reveal the uniform dispersion of the spheroidal growth of the γ'phase within the γ matrix after prolonged thermal exposure.The coarsening behavior of the γ'phase conforming to the Lifshitz-Slyozov-Wagner(LSW)model.The discontinuous carbides were precipitated around the eutectic after thermal exposure,but no topological close-packed(TCP)phase was generated.The creep tests were carried out at 760℃/662 MPa after long-term thermal exposure,the creep life of superalloy decreased due to the tissue degradation while the facture elongation increased as the thermal exposure time increased.Specifically,the creep fracture life dropped by 81.1%after 3 000h of thermal exposure.The reduction in creep life was mainly attributed to the coarsening of the γ'phase,degradation of the carbide,and increased creep porosity.Additionally,the decomposed MC carbide transformed into the M23 C6 carbide,which collapsed and gathered into micropores promote crack expansion.Furthermore,the dislocation network during creep was disrupted under thermal exposure and the dislocations cut through the γ'phase movement,which further reducing the creep fracture life.The results provide a reference for the service life prediction of IN792 LC single crystal superalloy at service temperature.
关键词
单晶高温合金/热暴露/组织退化/蠕变/碳化物Key words
single crystal superalloy/thermal exposure/microstructure degradation/creep/carbide引用本文复制引用
基金项目
国家自然科学基金(52271035)
上海市青年科技启明星项目(20 QA1403800)
上海市青年科技启明星项目(21 QC1401500)
上海市科委项目(21511103600)
上海市科委项目(20511107700)
出版年
2024
NETL
NSTL
万方数据