压力容器2025，Vol.42Issue(2)：1-9,9.DOI:10.3969/j.issn.1001-4837.2025.02.001
IN718合金高温裂纹扩展的环境依赖性:氧化诱导沿晶开裂与能量条件统一机理
Environmental dependence of high-temperature crack propagation in IN718 alloy:Oxidation-induced intergranular cracking and unified energy criterion mechanism
摘要
Abstract
The crack propagation behavior of nickel-based superalloys under high-temperature oxidation environments is critical for their service reliability.This study focuses on IN718 alloy,conducting fatigue crack growth(FCG)and creep-fatigue crack growth(CFCG)tests at 650℃in vacuum(≤5×10-3 Pa)and atmospheric environments.Scanning electron microscopy(SEM)and electron backscatter diffraction(EBSD)were employed to systematically analyze the effects of oxidation damage on crack propagation mechanisms.Results show that the fatigue crack growth rate in air is 3～4 times higher than in vacuum,with near-threshold crack propagation dominated by intergranular fracture in air,whereas transgranular fracture prevails in vacuum,accompanied by a significantly lower fatigue crack growth threshold.In CFCG tests,a 60 s hold time in air increases the crack growth rate by nearly two orders of magnitude,while the same hold time in vacuum has negligible acceleration effects.Fractography reveals that oxidation promotes intergranular cracking and crack closure effects,while crack tip plasticity in vacuum conforms to small-scale yielding conditions.Energy-based analysis demonstrates the unified energy criterion for crack propagation under grain boundary oxidation mechanisms in IN718 alloy.This study provides experimental and theoretical foundations for oxidation-related crack propagation theories and engineering applications of nickel-based superalloys.关键词
IN718合金/使役性能评价/裂纹扩展/氧化损伤/晶界氧化Key words
IN718 alloy/service performance evaluation/crack propagation/oxidation damage/grain boundary oxidation分类
机械工程引用本文复制引用
刘兰舟,高怡斐,陈新,刘占彬,任萱,诸明良..IN718合金高温裂纹扩展的环境依赖性:氧化诱导沿晶开裂与能量条件统一机理[J].压力容器,2025,42(2):1-9,9.基金项目
国家重点研发计划项目(2023YFB3712100) （2023YFB3712100）
