Microstructural characterization, formation mechanism and fracture behavior of the needle δ phase in Fe–Ni–Cr type superalloys with high Nb content》.pdfVIP

Materials Characterization 109 (2015) 36–42 Contents lists available at ScienceDirect Materials Characterization journal homepage: /locate/matchar Microstructural characterization, formation mechanism and fracture behavior of the needle δ phase in Fe–Ni–Cr type superalloys with high Nb content Yongquan Ning a,⁎, Shibo Huang b, M.W. Fu c, Jie Dong d a School of Materials Science Engineering, Northwestern Polytechnical University, Xian 710072, PR China b Anshan Iron Steel Group Corporation Bayuquan Subsidiary Company, Bayuquan 115007, PR China c Department of Mechanical Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, PR China d Inspection Research Institute of Boiler Pressure Vessel of Jiangxi Province, Nanchang 330029, PR China a r t i c l e i n f o a b s t r a c t Article history: Microstructural characterization, formation mechanism and fracture behavior of the needle δ phase in Fe–Ni–Cr Received 4 July 2015 type superalloys with high Nb content (GH4169, equivalent to Inconel 718) have been quantitatively investigat- Received in revised form 13 September 2015 ed in this research. The typical microstructures of δ phases with the stick, mixed and needle shapes obviously Accepted 16 September 2015 present in Inconel 718 after the isothermal upsetting at the temperature of 980–1060 °C with the initial strain Available online 21 September 2015 −3 −1 −1 rate of 10 –10 s . It is found that the shape of the δ phase has a great effect on the mechanical properties