摘要
选区激光熔化的制造过程不可避免地会在构件内部和表面产生缺陷,如何从“合于使用”的角度评价缺陷微观尺度扩展行为对结构寿命周期服役完整性的影响是目前亟需解决的主要问题之一.为了定量揭示疲劳裂纹萌生行为,借助Tanaka-Mura位错模型描述选区激光熔化成形GH3536合金的疲劳裂纹萌生及短裂纹扩展情况,分析由于缺陷位置、缺陷尺寸和缺陷类型等导致疲劳裂纹的表面和内部萌生的竞争情况.结果表明,随着缺陷距表面距离的减小或等效缺陷尺寸的增加,疲劳失效模式由表面变为内部失效;选区激光熔化成形GH3536存在对应条件下的损伤容限,当缺陷尺寸较小时,构件的裂纹萌生模式不发生变化,但随着缺陷数量增多,疲劳短裂纹的扩展路径发生多次偏转且萌生寿命明显降低.创新点:(1)建立了跨尺度裂纹扩展有限元模型,量化研究了选区激光熔化成形GH3536合金的疲劳裂纹萌生及短裂纹扩展情况.(2)分析了疲劳裂纹的表面和内部萌生的竞争机制与缺陷位置、尺寸和缺陷类型等之间的关系.
During selective laser melting(SLM)process,defects will be formed inevitably inside and on the surface of the additive manufacturing component.Therefore,it is important to evaluate the impact of crack propagation at the microscale on service integrity of structures throughout their life cycle from the perspective of fitness for service.In order to quantitatively reveal the initiation behavior of fatigue cracks,the Tanaka-Mura dislocation model was used to explain the fatigue crack initiation and short crack propagation of SLM formed GH3536 alloy.The competition mechanism between the surface and internal initiation of fatigue cracks caused by defect location,defect size,and defect type was analyzed.The results indicate that as the distance from the defect to the surface decreases or the equivalent defect size increases,the fatigue failure mode changes from surface failure to internal failure.SLM formed GH3536 exhibits damage tolerance under corresponding conditions:when the defect size is small,the crack initiation mode of the additive manufacturing component remains the same;while with the rising number of defects,the fatigue short crack propagation path deflects several times and the initiation life decreases significantly.Highlights:(1)A cross scale crack propagation finite element model was established,the fatigue crack initiation and short crack propagation of SLM formed GH3536 alloy were quantitatively studied.(2)The competition mechanism between the surface and internal initiation of fatigue cracks and the relationship among defect location,size,and defect type were analyzed.
作者
赵洋洋
林可欣
王颖
龚宝明
ZHAO Yangyang;LIN Kexin;WANG Ying;GONG Baoming(Tianjin University,Tianjin,300072,China)
出处
《焊接学报》
EI
CAS
CSCD
北大核心
2023年第7期1-8,I0003,共9页
Transactions of The China Welding Institution
基金
国家自然科学基金资助项目(52075366)。
