真空熔模铸造Ni基涡轮叶片氧化物缺陷分析

Analysis on Oxide Defects in Ni-based Turbine Blades by Vacuum Investment Casting

采用镍基超耐热不锈钢在真空条件下铸造涡轮叶片,通过金相显微镜和扫描电子显微镜对涡轮叶片中的氧化物缺陷进行研究。结果表明,隔离区域具有高的碳化物密度和裂缝网络。试样裂缝表面,可以观察到薄膜状夹杂物。在未隔离区域处的裂缝表面具有很多并且广泛分布的薄膜。薄膜主要由铝和铬的氧化物组成。薄膜是在铸造浇注时位于液体金属表面之上的薄膜夹带处生成。它与两端薄膜夹带形成可观察到的裂缝和碳化物。

Turbine blades of a nickel based superalloy were fabricated by vacuum investment casting. The oxides in turbine blades were observed by optical microscopy and scanning electron microscopy. The results show that the segregated areas has a high density of carbides and a network of cracks, there is a kind of film-like inclusion on the cracked surface of the specimen, and a large and widely distributed film on the crack surface at the non-isolated region. The film consists mainly of aluminum and chromium oxides. The film is formed at the film entrainment above the liquid metal surface during pouting process, it forms visible cracks and carbides precipitation with both ends of the film.