摘要
研究了单晶高温合金在持久、拉伸和低周疲劳条件下的损伤与断裂特征。结果表明:单晶合金高温持久微观断裂方式为沿原始微孔洞扩展的微孔聚集型断裂,中温持久微观断裂方式为微孔聚集型断裂与滑移剪切断裂共存的混合型断裂;高温拉伸首先在内部以微孔聚集型模式开裂,最后阶段以滑移剪切的方式发生断裂,微孔聚集型断裂过程占主要地位,中温拉伸以纯滑移剪切的方式发生断裂,断口由一个平面组成;低周疲劳断裂由裂纹萌生、裂纹稳定扩展和裂纹失稳扩展3个阶段组成。断口呈现多源开裂特征,疲劳裂纹一般萌生于表面。疲劳裂纹扩展初期断口基本与主应力方向垂直,随着疲劳裂纹扩展,断口表现为与主应力约成45°的平面特征。
The damage and fracture characteristics of a single crystal （SC） superalloy were investigated under the conditions of stress rupture, tension and low-cycle fatigue. The results show that during high-temperature stress rupture testing, the SC superalloy fractured in the mode of microvoid coalescence; during middle-temperature stress rupture testing, the SC superalloy fractured under the co-effect of microvoid coalescence and shear by slip. During high-temperature tensile testing, the SC superalloy cracked in the mode of microvoid coalescence in the early stage and then fractured in the mode of shear by slip; the microvoid coalescence damage course is dominant during the whole fracture course. During middle-temperature tensile testing, the SC superalloy fractured in the mode of shear by slip, and the fracture surface was a plane surface. The low-cycle fatigue fracture is composed of three stages： crack initiation, stable propagation and unstable propagation. The low-cycle fatigue fracture surface had more than one source zones and the cracks commonly initiated from the surface. The fracture surface forming in the initial stage is perpendicular to the principal stress axis, and then the cracks propagated along the direction 45 degree away from the principal stress axis.
出处
《失效分析与预防》
2012年第3期148-152,166,共6页
Failure Analysis and Prevention
关键词
单晶高温合金
持久
拉伸
低周疲劳
损伤
single crystal superalloy
stress rupture
tension
low-cycle fatigue
damage
