CAJ | 학술논문

对DD6单晶高温合金在高温低周(980℃、760℃)及疲劳/蠕变交互作用的断裂特征进行了研究。结果表明：DD6单晶高温合金高温低周疲劳断口往往呈多源开裂特征，裂纹萌生于试样的表面或亚表面，疲劳裂纹在刚萌生时沿着一定的小平面进行扩展，扩展区主要由垂直于裂纹扩展方向的疲劳条带和河流花样组成，瞬断区为类解理台阶形貌，裂纹扩展初期断口基本与主应力方向垂直，随着疲劳裂纹的扩展，断口呈现与主应力约成45°的平面特征；低周疲劳/蠕变交互作用的断裂特征与相同应变条件下低周疲劳断口总体形貌相似，但也一些不同之处，如断口整体氧化严重、疲劳扩展区面积明显减小。
대DD6단정고온합금재고온저주(980℃、760℃)급피로/연변교호작용적단렬특정진행료연구。결과표명：DD6단정고온합금고온저주피로단구왕왕정다원개렬특정，렬문맹생우시양적표면혹아표면，피로렬문재강맹생시연착일정적소평면진행확전，확전구주요유수직우렬문확전방향적피로조대화하류화양조성，순단구위류해리태계형모，렬문확전초기단구기본여주응력방향수직，수착피로렬문적확전，단구정현여주응력약성45°적평면특정；저주피로/연변교호작용적단렬특정여상동응변조건하저주피로단구총체형모상사，단야일사불동지처，여단구정체양화엄중、피로확전구면적명현감소。
The fracture features of single crystal superalloy DD6 were investigated under the condition of low-cycle fatigue ( 980℃, 760℃) and fatigue-creep. The results show that the low-cycle fatigue fracture surface had more than one source zone and the fatigue cracks initiated at surface or subsurface of the specimens. The fatigue cracks propagated along the crystallographic plane first and then perpendicularly to the loading axis. Typical fatigue striations and river pattern formed in the steady propagation stage. Like-cleavage steps were observed at the fast fracture zone. 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. 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:more serious oxidation and smaller extension zone.