摘要
高参数超超临界机组是未来火电技术的核心研究和发展方向,新型镍铁基高温合金HT650T(GH4650T)是650℃等级机组过热器、再热器用重要的候选材料,本研究将固溶态HT650T合金管材分别置于650℃和700℃进行0~10000 h的等温时效实验,分析了时效过程中合金强化相、晶内和晶界碳化物等微观组织以及室温冲击韧性的变化趋势。结果表明:时效过程中合金主要强化相γ′相的粗化受基体元素扩散控制,粗化动力学遵循Lifshitz-Slyozov-Wagner熟化规律。随时效时间的延长,晶界MX相的变化不明显,M 23 C 6析出量增多且宽化,晶界碳化物在时效至10000 h仍保持不连续的形态,未发现有害相析出。室温冲击韧性的下降与晶界碳化物的粗化具有关联性,时效后期冲击韧性趋于稳定,表明HT650T具有良好的组织和性能稳定性,研究结果可为HT650T合金的工程应用提供理论和实验依据。
High-parameter ultra-supercritical unithas been the core research and development direction of future thermal power technology,and the new Ni-Fe based superalloy HT650T(GH4650T)is an important candidate material for superheater and reheater of 650℃grade unit.In this work,the unstressed exposure tests were conducted at 650℃and 700℃for 0—10000 h,respectively.The microstructure evolution of the strengthening phases,intergranular and grain boundary carbides and the trend of impact toughness at room temperature during aging process were analyzed.The results showed that the coarsening ofγ′phase was controlled by the diffusion of the matrix elements,and the growth kinetics followed the Lifshitz-Slyozov-Wagner ripening law.The grain boundary MX phase did not change significantly with the aging time,and the precipitation of M 23 C 6 increased and widened.The grain boundary carbide remained discontinuous at 10000 h after thermal exposure,and no harmful precipitates were found.The decrease of impact toughness at room temperature was related to the coarsening of crystal boundary carbide,and the impact toughness tended to stabilize in the later stage of aging,indicating that HT650T has good stability in microstructure and properties.The research can provide theoretical and experimental basis for engineering application of HT650T alloys.
作者
李力敏
党莹樱
黄锦阳
刘鹏
李沛
鲁金涛
袁勇
LI Limin;DANG Yingying;HUANG Jinyang;LIU Peng;LI Pei;LU Jintao;YUAN Yong(Xi’an Thermal Power Research Institute Co.,Ltd.,Xi’an 710054,China)
出处
《材料导报》
EI
CAS
CSCD
北大核心
2024年第18期214-219,共6页
Materials Reports
基金
中国华能集团有限公司科技项目(HNKJ20-H41)
西安热工研究院有限公司研发基金项目(TA-20-TYK03,TA-23-TYK04)
国家自然科学基金(52271070)
陕西省自然科学基础研究计划项目(2023-JC-QN-0406)。
关键词
镍铁基高温合金
长期时效
组织稳定性
冲击韧性
Ni-Fe based superalloy
long-term exposure
microstructural stability
impact toughness
