Observation and Numerical Prediction of Concentration Distribution at Cast Coating Interface of Solid Pt, Ir, Re Using Liquid Ni-based Alloys Machiko Ode, Hisao Esaka, Akira Ishida, Susumu Takamori and Hideyuki Murakami Research Center for Structural Materials (RCSM), National Institute for Materials Science (NIMS) The applicability of a cast-coating process for improving the oxidation resistance of cast Ni-based superalloys was evaluated. Specifically, metallic plates of Pr, Ir, and Re expected to improve oxidation resistance when they are enriched on the cast alloys were placed in a mold and cast coating using Ni-10at%Al alloy was performed in order to investigate the formation of the Pt, Ir, or Re-enriched layer on the casting surface. Then the microstructure of the Ni-based alloy/specimen interface was observed. To analyze the concentration profile in the interdiffusion region, solidification and diffusion simulations were performed. It was found that Pt easily dissolves into the molten Ni-based alloy, and Re cannot expected to modify cast metal surfaces due to its low solubility into the Ni-10at%Al alloy. On the other hand, Ir forms smooth interdiffusion layer, and numerical calculations predicted that Ir can maintain the modification ability even in a process time of 1 hour, which is equivalent to the casting time of Ni-based turbine blades. Delayed Fracture of Ultra-high Strength Steel Processed by Y. Kimura 1 and T. Inoue 1 1 Research Center for Structural Materials, National Institute for Materials Science (NIMS) 38Warm tempforming is a thermomechanical treatment that deforms tempered martensite at elevated temperatures. Warm tempforming using multi-pass caliber rolling on medium-carbon low-alloy steel can create an ultrafine elongated grain (UFEG) structure with a strong <110>// rolling direction (RD) fiber texture. In this presentation, delayed fracture properties of the warm tempformed steel with UFEG structure will be presented. 0.4%C-2%Si-1%Cr-1%Mo steel was quenched and tempered at 500°C and then subjected to warm tempforming using multi-pass caliber rolling to create the UFEG structure. Delayed fracture properties were evaluated using slow-strain-rate-test and hydrogen immersion test. The results showed that at ultra-high tensile strength of 1.8 GPa, the warm tempformed (TF) samples with UFEG structure exhibited much higher delayed fracture resistance than the quenched and tempered (QT) samples. Delayed fracture behavior in long-term outdoor exposure tests is also presented for ultra-high strength bolts fabricated from TF and QT samples. PP11--0077 PP11--0088 Poster Presentation ｜NIMS Award Symposium 2023 P1 ｜ ProcessWarm Tempforming
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