The Experts below are selected from a list of 3684 Experts worldwide ranked by ideXlab platform
M Iben Houria - One of the best experts on this subject based on the ideXlab platform.
-
influence of Casting Defect and sdas on the multiaxial fatigue behaviour of a356 t6 alloy including mean stress effect
International Journal of Fatigue, 2015Co-Authors: Raouf Fathallah, M Iben Houria, Yves Nadot, Daan M. MaijerAbstract:Abstract The effect of mean stress on the multiaxial High Cycle Fatigue (HCF) behaviour of cast A356-T6 alloy containing natural and artificial Defects with varying Secondary Dendrite Arming Spacing (SDAS) has been investigated experimentally. Tension, torsion and combined tension–torsion fatigue tests have been performed for two loading ratios: R σ = 0 and R σ = −1. A Scanning Electron Microscopy (SEM) was used to perform fractographic analysis of the fracture surfaces to characterise the Defect causing failure. In order to gauge the effect of mean stress and Defects, the results are reported with standard Kitagawa and Haigh diagrams. A surface response method has been employed to characterise the influence of Defect size and SDAS on the fatigue limit. Relationships and correlations describing the observed behaviour have been incorporated in the Defect Stress Gradient (DSG) criterion with the goal of determining the influence of Defects on the fatigue limit through a stress gradient approach. Results clearly show that: (i) the mean stress has a detrimental effect on the fatigue limit. This effect is a function of the loading, which is most pronounced under tension, less under combined tension–torsion, and least pronounced under torsion conditions; (ii) in the absence of Defects, the SDAS controls the fatigue limit of cast A356, this effect is much more important under torsion loading; (iii) the DSG criterion is improved by the mean of a parameter describing the microstructure effect through the SDAS.
Makoto Yoshida - One of the best experts on this subject based on the ideXlab platform.
-
mechanical properties of inconel 718 nickel based superalloy around solidus temperature
Journal of The Japan Institute of Metals, 2012Co-Authors: Tsubasa Ohashi, Ryosuke Goto, Kenji Muto, Makoto YoshidaAbstract:Nickel-based superalloys have been applied to gas turbine and aircraft jet engine parts due to superior high temperature strength and corrosion resistance. However, Casting Defect such as solidification cracking often occurs. In order to increase productivity of precision Casting and various shape Casting processes, predicting the occurrence of solidification cracking by using CAE(Computer Aided Engineering) should be essential. Therefore, it is necessary to obtain mechanical properties in the state of solid-liquid coexistence. In this study, we try to get high temperature (around solidus temperature) mechanical properties of the nickel-based superalloy such as Inconel 718 by using originally developed tensile test. In the previous reports, flat distribution of temperature in the gage length, and crack initiation strain were not ensured. On the other, the developed device ensured within 3℃ of the temperature distribution in the gage length as to the Inconel 718. Tensile strain was measured by using in-situ observation of marker on the surface of the specimen. As a result, Stress-Strain curve, crack initiation stress, and crack initiation strain of Inconel 718 were obtained.
-
mechanical properties of inconel 718 nickel based superalloy around solidus temperature
Journal of The Japan Institute of Metals, 2012Co-Authors: Tsubasa Ohashi, Ryosuke Goto, Kenji Muto, Makoto YoshidaAbstract:Nickel-based superalloys have been applied to gas turbine and aircraft jet engine parts due to superior high temperature strength and corrosion resistance. However, Casting Defect such as solidification cracking often occurs. In order to increase productivity of precision Casting and various shape Casting processes, predicting the occurrence of solidification cracking by using CAE(Computer Aided Engineering) should be essential. Therefore, it is necessary to obtain mechanical properties in the state of solid-liquid coexistence. In this study, we try to get high temperature (around solidus temperature) mechanical properties of the nickel-based superalloy such as Inconel 718 by using originally developed tensile test. In the previous reports, flat distribution of temperature in the gage length, and crack initiation strain were not ensured. On the other, the developed device ensured within 3℃ of the temperature distribution in the gage length as to the Inconel 718. Tensile strain was measured by using in-situ observation of marker on the surface of the specimen. As a result, Stress-Strain curve, crack initiation stress, and crack initiation strain of Inconel 718 were obtained.
Jonathan Cormier - One of the best experts on this subject based on the ideXlab platform.
-
benefits of high gradient solidification for creep and low cycle fatigue of am1 single crystal superalloy
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2015Co-Authors: S Steuer, P Villechaise, Tresa M Pollock, Jonathan CormierAbstract:Abstract The influence of high thermal gradient processing on the creep and low cycle fatigue properties of the AM1 Ni-based single crystal superalloy has been studied. Isothermal creep (from 750 °C up to 1200 °C) and low cycle fatigue (750 °C and 950 °C) experiments were performed for AM1 alloy solidified with a conventional radiation cooled (Bridgman) and higher thermal gradient liquid-metal cooled (LMC) Casting process to produce coarse and finer-scaled dendritic structures, respectively. There was no significant effect of the Casting technique on creep properties, due to the very similar microstructures (γ′-size and γ-channel width) established after full heat treatment of both Bridgman and LMC samples. For low cycle fatigue properties, the benefit of the higher gradient LMC process was dependent on the testing temperature. At 750 °C, cracks primarily initiated at pores created by solidification shrinkage in both Bridgman and LMC samples. Samples produced by the LMC technique demonstrated fatigue lives up to 4 times longer, compared to the Bridgman samples, due to refined porosity. At 950 °C the low cycle fatigue properties of the LMC and conventionally solidified material were not distinguishable due to a shift of crack initiation sites from internal pores to oxidized surface layers or near-surface pores. The benefit of the LMC approach was, however, apparent in fatigue at 950 °C when testing in a vacuum environment. Based on these results, a crack initiation model based on the local slip activity close to Casting Defect is proposed.
Daan M. Maijer - One of the best experts on this subject based on the ideXlab platform.
-
influence of Casting Defect and sdas on the multiaxial fatigue behaviour of a356 t6 alloy including mean stress effect
International Journal of Fatigue, 2015Co-Authors: Raouf Fathallah, M Iben Houria, Yves Nadot, Daan M. MaijerAbstract:Abstract The effect of mean stress on the multiaxial High Cycle Fatigue (HCF) behaviour of cast A356-T6 alloy containing natural and artificial Defects with varying Secondary Dendrite Arming Spacing (SDAS) has been investigated experimentally. Tension, torsion and combined tension–torsion fatigue tests have been performed for two loading ratios: R σ = 0 and R σ = −1. A Scanning Electron Microscopy (SEM) was used to perform fractographic analysis of the fracture surfaces to characterise the Defect causing failure. In order to gauge the effect of mean stress and Defects, the results are reported with standard Kitagawa and Haigh diagrams. A surface response method has been employed to characterise the influence of Defect size and SDAS on the fatigue limit. Relationships and correlations describing the observed behaviour have been incorporated in the Defect Stress Gradient (DSG) criterion with the goal of determining the influence of Defects on the fatigue limit through a stress gradient approach. Results clearly show that: (i) the mean stress has a detrimental effect on the fatigue limit. This effect is a function of the loading, which is most pronounced under tension, less under combined tension–torsion, and least pronounced under torsion conditions; (ii) in the absence of Defects, the SDAS controls the fatigue limit of cast A356, this effect is much more important under torsion loading; (iii) the DSG criterion is improved by the mean of a parameter describing the microstructure effect through the SDAS.
Bo Chen - One of the best experts on this subject based on the ideXlab platform.
-
transition from internal to surface crack initiation of a single crystal superalloy in the very high cycle fatigue regime at 1100 c
International Journal of Fatigue, 2021Co-Authors: Zihua Zhao, F Zhang, Bo ChenAbstract:Abstract Transition from internal to surface crack initiation is controlled by oxidation assisted fatigue-crack process in the very-high-cycle fatigue regime. Between 760 and 1000 °C, single crack initiation site is associated with internal Casting Defect, followed by a crystallographic Stage I propagation. By contrast, multiple surface crack initiation sites appear at 1100 °C, as the consequence of internal oxide penetration. The fatal crack follows a Mode I propagation and oxygen can diffuse into the material along the crack path. γ′-phase depletion appears surrounding the oxidised and cracked regions, while localised rafting can occur close to the crack tip.