Short Fatigue Crack Growth M at Elevated Temperatures and in Oxidative Atmospheres Short Fatigue Crack Growth M at Elevated Temperatures and in Oxidative Atmospheres H. Nishikawa 1, K. Habib 1, Y. Furuya 1, T. Hara 1, T. Osada 1 and K. Kawagishi 1 1 Research Center for Structural Materials, National Institute for Materials Science (NIMS) H. Nishikawa 1, K. Habib 1, Y. Furuya 1, T. Hara 1, T. Osada 1 and K. Kawagishi 1 1 Research Center for Structural Materials, National Institute for Materials Science (NIMS) In this study, to elucidate the oxidation effect on the short fatigue crack growth (SFCG) characteristics of Ni-Co based TMW-4M3 superalloy, fatigue tests were conducted at room/elevated In this study, to elucidate the oxidation effect on the short fatigue crack growth (SFCG) temperature in air/vacuum and three-dimensional microscopic observation of the SFCs using a plasma characteristics of Ni-Co based TMW-4M3 superalloy, fatigue tests were conducted at room/elevated focused ion beam – scanning electron microscope (PFIB – SEM) system. Fatigue lives tested under temperature in air/vacuum and three-dimensional microscopic observation of the SFCs using a plasma vacuum at elevated temperature were comparable to those at room temperature while those tested at focused ion beam – scanning electron microscope (PFIB – SEM) system. Fatigue lives tested under elevated temperatures in air showed shorter fatigue life in higher stress regions and longer fatigue life vacuum at elevated temperature were comparable to those at room temperature while those tested at in lower stress regions than the others. In situ observation of SFCs at elevated temperatures in air elevated temperatures in air showed shorter fatigue life in higher stress regions and longer fatigue life revealed SFCG deceleration in the small ΔK regions and acceleration in large ΔK regions. SFCs in lower stress regions than the others. In situ observation of SFCs at elevated temperatures in air opening/closing behaviors at elevated temperatures measured by digital image correlation (DIC) showed revealed SFCG deceleration in the small ΔK regions and acceleration in large ΔK regions. SFCs the crack opening stress to be higher at elevated temperature in air, possibly due to oxide-induced crack opening/closing behaviors at elevated temperatures measured by digital image correlation (DIC) showed closure. However, the crack closure effect did not fully explain the difference in FCG rate between room the crack opening stress to be higher at elevated temperature in air, possibly due to oxide-induced crack and elevated temperatures in air. Three-dimensional investigations revealed SFCs to form at elevated closure. However, the crack closure effect did not fully explain the difference in FCG rate between room temperatures in air, showing straight transgranular FCG to be insensitive to microstructure in slow and elevated temperatures in air. Three-dimensional investigations revealed SFCs to form at elevated growth regions, and intergranular FCG to precede that in the surrounding material in fast growth regions, temperatures in air, showing straight transgranular FCG to be insensitive to microstructure in slow in contrast to microstructural SFCs features at room temperature. It appears that slow and straight unique growth regions, and intergranular FCG to precede that in the surrounding material in fast growth regions, SFCG at elevated temperatures might occur due to intermittent brittle fracture of oxides formed at the in contrast to microstructural SFCs features at room temperature. It appears that slow and straight unique crack tip. SFCG at elevated temperatures might occur due to intermittent brittle fracture of oxides formed at the crack tip. Estimation of M Estimation of MDayuan Liu 1, Ta-Te Chen 2 and Ikumu 1 Graduate School of Science and Technology, University of Tsukuba Dayuan Liu 1, Ta-Te Chen 2 and Ikumu 2 Center for Basic Research on Materials, National Institute for Materials Science (NIMS) 1 Graduate School of Science and Technology, University of Tsukuba 2 Center for Basic Research on Materials, National Institute for Materials Science (NIMS) Instrumented indentation test, also known as depth-sensing indentation test, is an extension of the hardness test, in which the applied load and penetration depth are measured. The elastic stiffness and Instrumented indentation test, also known as depth-sensing indentation test, is an extension of the hardness can be estimated based on the resulting relationship between load P and depth h (i.e., the P-h hardness test, in which the applied load and penetration depth are measured. The elastic stiffness and curve). An inhomogeneous stress state is produced in the instrumented indentation test compared with hardness can be estimated based on the resulting relationship between load P and depth h (i.e., the P-h the uniaxial stress state. Nevertheless, various estimation approaches for the stress-strain relationship curve). An inhomogeneous stress state is produced in the instrumented indentation test compared with corresponding to the tensile test have been proposed based on the results of instrumented indentation the uniaxial stress state. Nevertheless, various estimation approaches for the stress-strain relationship tests. It is recognized that a unique stress-strain relationship cannot be estimated from the P-h curve of corresponding to the tensile test have been proposed based on the results of instrumented indentation a single indentation using a standard sharp indenter. In this context, a dual-indenter approach and a tests. It is recognized that a unique stress-strain relationship cannot be estimated from the P-h curve of spherical indenter approach using two sharp indenters with different apex angles enable us to determine a single indentation using a standard sharp indenter. In this context, a dual-indenter approach and a a unique set of material parameters in a simple constitutive model. In this study, we focus on the spherical indenter approach using two sharp indenters with different apex angles enable us to determine interactions between the existing and subsequent indentation tests to extract the plastic properties from a unique set of material parameters in a simple constitutive model. In this study, we focus on the the result of two indentation tests performed at neighboring positions. With this view, finite element interactions between the existing and subsequent indentation tests to extract the plastic properties from simulations are performed to design suitable indentation conditions and draw the response surfaces of the result of two indentation tests performed at neighboring positions. With this view, finite element the indentation results to determine the material constants of the plastic constitutive model. Eventually, simulations are performed to design suitable indentation conditions and draw the response surfaces of the proposed approach is validated in applications to aluminum alloys and stainless steel in which the the indentation results to determine the material constants of the plastic constitutive model. Eventually, material constants are read from the response surfaces. the proposed approach is validated in applications to aluminum alloys and stainless steel in which the material constants are read from the response surfaces. Poster Presentation ｜NIMS Award Symposium 2023echanism in Ni-Co Based Superalloy echanism in Ni-Co Based Superalloy echanical Properties of Alloys Using Neighboring Indentation Test echanical Properties of Alloys Using Neighboring Indentation Test Watanabe 1, 2 Watanabe 1, 2 P2 ｜ CharacterizationPP22--2233 PP22--2233 PP22--2244 PP22--2244 55
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