CAJ | 학술논문

发动机涡轮增压器用镍基铸造高温合金K418C铸锭经快速感应重熔浇铸零件时发生开裂。运用光学显微镜、扫描电子显微镜( SEM)、电子探针微束分析仪( EPMA)和透射电子显微镜( TEM)对断裂铸锭表面进行了宏观形貌及显微组织分析,并对断裂原因进行探讨。结果表明：断口附近的显微组织异常,黑色块状析出相分布于基体上,伴有穿晶裂纹,电子衍射分析表明黑色块状组织为β-NiAl,铸锭局部Al偏高使得铸锭在凝固时析出脆性相,再次快速加热产生的热应力使得裂纹在β-NiAl相与基体之间萌生并快速扩展贯穿整个铸锭,导致瞬间断裂。
발동궤와륜증압기용얼기주조고온합금K418C주정경쾌속감응중용요주령건시발생개렬。운용광학현미경、소묘전자현미경( SEM)、전자탐침미속분석의( EPMA)화투사전자현미경( TEM)대단렬주정표면진행료굉관형모급현미조직분석,병대단렬원인진행탐토。결과표명：단구부근적현미조직이상,흑색괴상석출상분포우기체상,반유천정렬문,전자연사분석표명흑색괴상조직위β-NiAl,주정국부Al편고사득주정재응고시석출취성상,재차쾌속가열산생적열응력사득렬문재β-NiAl상여기체지간맹생병쾌속확전관천정개주정,도치순간단렬。
K418C Ni-based superalloy casting ingots for engine turbochargers fractured during casting. Macrostructure and microstructure were studied by optical microscopy, scanning electrical microscopy ( SEM ) , electrical probe micro-analysis ( EPMA) and transmission electron microscopy ( TEM) , and the fracture mechanism was discussed. The results show that there were an amount of abnormal black phases near the fracture of K418C casting ingot, which distributed on the matrix, companied with transgranular crack. The electron diffraction result indicated that the black phase is β-NiAl, which is brittle and resulted from local segregation of Al during solidification. The cracks between β-NiAl and matrix were induced by heat stress during rapid heating and propagated rapidly across the whole ingot. Finally, the casting ingot fractured instantly.