摘要
为了探究DD6合金在高温工作环境服役期间的疲劳裂纹扩展机制,对DD6合金进行630℃、660℃、730℃三个高温条件下的疲劳裂纹扩展试验,发现该合金呈现独特的双模式裂纹扩展特性:在扩展初始阶段,预制缺口几何约束与γ'沉淀强化相的协同作用主导裂纹沿[001]晶体取向的{001}解理面扩展;当应力强度因子增加,裂纹可以穿过γ'沉淀强化相时,位错滑移机制发生转变,此时位错优先在{111}最密排晶面族上运动,导致微观断口出现许多与载荷方向呈约45°{111}晶面族台阶面,同时单晶材料的各向异性特征导致裂纹扩展中试样宏观断口两侧出现显著的侧向斜面。该发现为航空发动机涡轮叶片用单晶合金的疲劳裂纹扩展机制与寿命预测提供了重要理论依据。
To investigate the fatigue crack propagation mechanisms of DD6 alloy under high-temperature service conditions,fatigue crack growth tests were conducted at 630℃,660℃,and 730℃.The results reveal a unique dual-mode crack propagation behavior in the alloy.During the initial propagation stage,synergistic effects of the prefabricated notch geometry constraint andγ' precipitate strengthening phases dominate crack propagation along the{001}cleavage planes aligned with the[001]crystallographic orientation.As the stress intensity factor increases,a transition in dislocation slip mechanisms occurs,where preferential activation of slip systems on the close-packed{111}crystallographic planes enables crack penetration throughγ'precipitate strengthering phases.This mechanism leads to the formation of microscale{111}step features oriented approximately 45° relative to the loading direction.Furthermore,the anisotropic nature of the single-crystal material induces prominent lateral inclined surfaces on both sides of the fracture morphology during crack propagation.These findings provide crucial theoretical foundations for understanding fatigue crack evolution mechanisms and lifetime prediction of singlecrystal superalloys used in aeroengine turbine blades.
作者
王甲贺
黄子琳
袁珂
方向
杨文鑫
王彦芳
WANG Jiahe;HUANG Zilin;YUAN Ke;FANG Xiang;YANG Wenxin;WANG Yanfang(Qingdao Sushi Haice Testing Technology Co.Ltd.,Qingdao 266000,Shandong China;AECC Hunan Aviation Powerplant Research Institute,Zhuzhou 412002,Hunan China)
出处
《河南科学》
2025年第8期1100-1106,共7页
Henan Science
基金
国家科技重大专项(J2019-VIII-0002-0163)。
关键词
DD6单晶合金
疲劳裂纹扩展
断口形貌
DD6 single-crystal superalloy
fatigue crack propagation
fracture morphology
