CAJ | 학술논문

研究了[011]取向的镍基单晶高温合金在750~980℃温度范围和200~680 MPa应力下的蠕变断裂特征。在扫描电镜上对各种实验状态下的蠕变断口和纵向剖面进行了详细观察。研究发现：在低温750℃和中温870℃不同初始蠕变应力条件下，枝晶间区亚晶界处不规则γ＇/γ界面是裂纹主要萌生场所，这些已萌生的裂纹在与外加应力轴垂直的(011)面上沿＜110＞和＜100＞两个方向扩展；980℃不同初始应力条件下，裂纹主要在合金中显微疏松孔洞处萌生，沿与外应力轴垂直的方向扩展。观察750℃和870℃不同应力状态蠕变试样的纵向剖面，对亚晶界区不规则γ＇相面积分数的测量和计算表明，用面积分数表征该合金[011]取向在中低温状态下的蠕变损伤程度是可行的。
연구료[011]취향적얼기단정고온합금재750~980℃온도범위화200~680 MPa응력하적연변단렬특정。재소묘전경상대각충실험상태하적연변단구화종향부면진행료상세관찰。연구발현：재저온750℃화중온870℃불동초시연변응력조건하，지정간구아정계처불규칙γ＇/γ계면시렬문주요맹생장소，저사이맹생적렬문재여외가응력축수직적(011)면상연＜110＞화＜100＞량개방향확전；980℃불동초시응력조건하，렬문주요재합금중현미소송공동처맹생，연여외응력축수직적방향확전。관찰750℃화870℃불동응력상태연변시양적종향부면，대아정계구불규칙γ＇상면적분수적측량화계산표명，용면적분수표정해합금[011]취향재중저온상태하적연변손상정도시가행적。
The creep fracture behavior of a [011] oriented single crystal nickel base superalloy was investigated in the tempera-ture range of 750 to 980℃ and the stress scope of 200 to 680 MPa. The fracture surfaces and longitudinal sections of crept specimens were examined by scanning electron microscopy ( SEM) . It is found that under different initial stresses at 750℃ and 870℃, creep cracks seem always to initiate at theγ'/γinterface on the interdendritic sub-boundary and propagate along the sub-boundary trace, and their cleavage planes expand along<110> and<100> on the (011) plane. But under different stresses at 980℃, creep cracks initiate at inherent casting pores and slowly propagate perpendicular to the axis of stress applied up to the final fast fracture. After observing the longitudinal sections of specimens crept under different stresses at 750℃ and 870℃, it is feasible for the area fraction of irregularγ' phase in the sub-boundary to characterize the creep damage level before collapsing of the superalloy along the [011] direction at the moderated and low temperatures.