DZ125高温合金断裂特征

Fracture Features of Directionally Solidified Superalloy DZ125

对DZ125定向凝固高温合金的室温、高温拉伸,高温低周、高周疲劳,以及疲劳/蠕变交互断裂特征进行了研究。结果表明:DZ125合金室温、高温拉伸断口具有类解理断裂、韧窝断裂和沿枝晶断裂的混合特征,断裂机制为中心微孔聚集型断裂;高温低周疲劳断裂断口与主应力方向垂直;高温高周疲劳断裂断口疲劳裂纹扩展第一阶段表现为类解理小平面和平行锯齿状断裂特征。低周/蠕变交互断裂特征与相同条件下低周疲劳断口主要存在3方面差异:疲劳扩展区面积明显减小;断口上的撕裂棱线较多且相互连接;断口上氧化严重,特别是在疲劳扩展区,存在明显的致密氧化层。

The fracture features of directionally solidified superalloy DZ125 were investigated under the condition of tension, low-cycle fatigue, high-cycle fatigue and fatigue-creep. The results show that the fracture surfaces of the tensile specimens present the mixed feature of quasi-cleavage feature, dimples and interdendritic fracture. The fracture mechanism of the tensile specimens is microvoid coalescence fracture. The fracture surfaces of the high-temperature low-cycle fatigue specimens are perpendicular to the main stress. The high-temperature high-cycle fracture surfaces forming during the first stage of fatigue crack propagation represent quasi-cleavage facet feature and parallel saw-tooth fracture feature. Compared with the fracture surfaces of the low-cycle fatigue specimens tested under the same condition, those of the fatigue-creep specimens have the following distinct features： smaller extension zone, more tearing ribs and more serious oxidation.