Effect of Casting Modulus on Microstructure and Segregation in K441 Superalloy Casting

• 来源期刊: 材料科学技术学报：英文版
• 学科: 工学
• 关键词: 铸造组织 高温合金 扫描电子显微镜 弹性模量 微观结构 平均晶粒尺寸 宏观偏析 光学显微镜
• 年，卷（期）: 2011,（9）
• 页码范围: 831-840
• 页数: 10页
• 分类号: TG146.21|TG132.32
• 语种: 英文

摘要

Four castings with different modulus have been designed to simulate different thickness sections of a turbine blade during casting process. The microstructure has been observed by optical microscopy （OM） and scanning electron microscopy （SEM）. The micro-segregation was tested by energy dispersive spectroscopy （EDS） and the macro-segregation was analyzed by using Metalscan 2500 spectrometers. The experimental results show that the microstructure of casting is affected by modulus apparently. The smaller the modulus, the finer the microstructure. The average grain size of castings with modulus of 0.29, 1.57, 3.10 and 5.0 mm is 0.3, 1.5, 2.7 and 4.3 mm, and the volume fraction of eutectic is 0, 0.1%, 0.2% and 1.0%, respectively. The micro/macro segregation is affected by the modulus apparently. The smaller the modulus, the lower the segregation level. When the modulus of casting increases, the content of AI increases, while the content of W, Cr and Mo decreases both in inner grain and near grain boundary. The content of AI and Mo in inner grain is higher than that near grain boundary, while the content of Cr and W in inner grain is lower than that near grain boundary.