摘要
首先对GH3230合金进行1000℃/100 h的等温氧化实验,然后进行了室温及700℃的拉伸试验和低周疲劳试验,获得了GH3230合金的S-N曲线,并对断口进行了分析。结果表明:等温氧化后形成的致密氧化层对GH3230合金起到了保护作用,对拉伸性能影响较小,但是对疲劳性能影响显著,使室温低周疲劳寿命升高、高温低周疲劳寿命显著降低。拉伸断口分布着大量韧窝,表明其为韧性断裂。高温拉伸试样的韧窝较大而深,与塑性较高这一特性一致。疲劳断口整体分为裂纹萌生区、扩展区与瞬断区,其中裂纹萌生区分为表面沿层起裂和脆性碳化物起裂。疲劳断裂为脆性断裂,室温疲劳试样边缘无明显裂纹,塑性滑移带明显,说明位错运动是主要的塑性变形机制。氧化试样的氧化层致密而完整,碳化物增多且弥散分布,使其疲劳寿命更高。700℃高温疲劳试样边缘产生多条次生裂纹,其裂纹扩展模式为沿晶穿晶的混合模式。没有观察到塑性滑移带,表明变形机制由位错滑移转为扩散蠕变或晶界滑移,氧化试样的氧化层破裂剥落,部分碳化物粗化聚集,使疲劳寿命降低。
I sothermal oxidation tests at 1000℃for 100 hours were conducted on GH3230 alloy,followed by tensile tests and low-cycle fatigue(LCF)tests at both room temperature and 700℃.The S-N curves of GH3230 alloy were established,and fracture surface analyses were performed.Results indicate that the dense oxide layer formed during isothermal oxidation provides effective protection for the alloy,exhibiting minimal impact on tensile properties but significantly influencing fatigue performance.Notably,it enhances room-temperature LCF life while significantly reducing high-temperature LCF life.Tensile fracture surfaces display abundant dimples,confirming ductile fracture characteristics.Larger and deeper dimples observed in high-temperature tensile specimens align with their superior plasticity.Fatigue fractures demonstrate three distinct zones:crack initiation,propagation,and final rupture.Crack initiation mechanisms involve surface layerinduced fracture and brittle carbideinduced cracking.Fatigue failure manifests as brittle fracture,with roomtemperature specimens showing no edge cracks but prominent plastic slip bands,suggesting dislocation motion as the dominant deformation mechanism.Oxidized specimens exhibit intact oxide layers and increased dispersion of carbides,contributing to improved fatigue resistance.In contrast,700℃LCF specimens develop multiple secondary cracks at edges,displaying intergranulartransgranular mixedmode propagation.The absence of plastic slip bands implies a transition in deformation mechanisms from dislocation glide to diffusion creep or grain boundary sliding.Degraded fatigue life in oxidized hightemperature specimens correlates with oxide layer spallation and carbide coarsening.
作者
王莉莎
曹睿
张亚玮
张继
WANG Lisha;CAO Rui;ZHANG Yawei;ZHANG Ji(State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals,Lanzhou University of Technology,Lanzhou 730050,China;School of Materials Science and Engineering,Lanzhou University of Technology,Lanzhou 730050,China;Beijing CISRI-Gaona Materials Technology Co.,Ltd.,Beijing 100081,China;Beijing Key Laboratory of Advanced High Temperature Materials,Central Iron and Steel Research Institute,Beijing 100081,China)
出处
《材料导报》
北大核心
2026年第3期147-155,共9页
Materials Reports
基金
中央引导地方科技发展专项(24ZYQA054)
甘肃省拔尖领军人才项目
甘肃省科技重大专项(23ZDGA010)
甘肃省重点研发计划(23YFGA0057)
国家自然科学基金(52175325
51961024
52071170)。
关键词
低周疲劳
GH3230镍基高温合金
等温氧化
氧化层
疲劳断裂机理
low-cycle fatigue
GH3230 nickel-based superalloy
isothermal oxidation
oxide layer
fatigue fracture mechanism
