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Masao Sakane - One of the best experts on this subject based on the ideXlab platform.

  • Creep rupture life and damage evaluation under Multiaxial Stress State for type 304 stainless steel
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2008
    Co-Authors: Shengde Zhang, Takashi Wakai, Masao Sakane
    Abstract:

    Abstract The biaxial creep damage of type 304 stainless steel is studied at 973 K. Biaxial tension creep tests were carried out using cruciform specimens under the principal Stress ratio ( λ ) of 0 ≦  λ  ≦ 1, where the principal Stress ratio is the ratio of y -directional principal Stress to x -directional Stress in the gage part of the specimen ( λ  =  σ y / σ x ). Creep rupture times under biaxial Stress conditions were shorter than those in uniaxial conditions at the same von Mises equivalent Stress. Earlier void nucleation and faster void growth were observed in creep tests at larger principal Stress ratio tests. Creep rupture times in biaxial Stress States were discussed in relation to the void observations.

  • Experimental Study of Ratcheting for SUS304 Stainless Steel and A1070 Aluminum Alloy
    Volume 1: Codes and Standards, 2007
    Co-Authors: Masao Sakane, Akihiko Inoue, Xu Chen, Kwang Soo Kim
    Abstract:

    This paper studies the cyclic ratcheting for two materials under Multiaxial Stress State. The two materials are SUS304 austenitic stainless steel and A1070 pure aluminum. The former material is known as a material that gives strong additional hardening and the latter material shows little additional hardening under nonproportional cyclic loading. The ratcheting behavior under 12 Stress-strain waveforms was extensively studied using hollow cylinder specimen. Ratcheting strain depended on the material and Stress-strain waveform. Anisotropic ratcheting was found in A1070 but isotropic ratcheting was observed in SUS304 steel.Copyright © 2007 by ASME

  • Evaluation of fatigue-creep life prediction methods in Multiaxial Stress State
    Nuclear Engineering and Design, 1991
    Co-Authors: Tatsuo Inoue, Masakazu Okazaki, Toshihide Igari, Masao Sakane, Shigeru Kishi
    Abstract:

    Abstract The present report covers the results of the benchmark project (B) by the Subcommittee on Inelastic Analysis and Life Prediction of High Temperature Materials, the Society of Materials Science, Japan, concerning the fatigue-creep life prediction under Multiaxial Stress condition of combined tension-compression and cyclic torsion. Multiaxial fatigue-creep tests for 2 1 4 Cr −1 Mo steel at 600°C were performed under both in-phase and out-of-phase strain-controlled wave patterns. Seven types of life prediction methods were employed; they are linear damage rule, strain range partitioning method, and methods by Majumdar, Ostergren, Krempl, Lemaitre-Plumtree-Chaboche and Bui-Quoc. In applying these methods two sets of life prediction schemes are adopted. One is the normal way that the fatigue-creep lives are predicted by the experimentally obtained Stress-strain response. Life prediction in the other way is made by employing the calculated Stress-strain relation by means of ten kinds of constitutive models described in the report of benchmark project (A). The predicted lives thus obtained were compared with the experimental data, and the accuracy of the life prediction methods was extensively discussed.

Z.f. Yue - One of the best experts on this subject based on the ideXlab platform.

  • V-Notched Bar Creep Life Prediction: GH3536 Ni-Based Superalloy Under Multiaxial Stress State
    Journal of Materials Engineering and Performance, 2016
    Co-Authors: Dongsheng Zhang, Junbiao Wang, Z.x. Wen, D.s. Liu, Z.f. Yue
    Abstract:

    In this study, creep experiments on smooth and circumferential V-type notched round bars were conducted in GH3536 Ni-based superalloy at 750 °C to identify notch strengthening effect in notched specimens. FE analysis was carried out, coupled with continuum damage mechanics (CDM), to analyze Stress distribution and damage evolution under Multiaxial Stress State. The creep deformation of smooth specimens and the rupture life of both smooth and notched specimens showed good agreement between experimental results and FE analysis predictions; the creep rupture life for the notched specimen was successfully predicted via the “skeletal point” concept. Both creep damage analysis and the observed fracture morphology suggest that creep rupture started first at the root in the V-type notched specimens, and shifted to the region close to the notch root when the notch was relatively shallow compared to U-type notched specimens.

  • A low-cycle fatigue life model of nickel-based single crystal superalloys under Multiaxial Stress State
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2004
    Co-Authors: J.s. Wan, Z.f. Yue
    Abstract:

    Abstract The low-cycle fatigue (LCF) behavior of smooth and notched specimens of nickel-based single-crystal superalloys DD3 was studied at 620 °C. Based on experimental results and finite element analysis results, a low-cycle fatigue life model has been proposed for the nickel-based single-crystal superalloys under Multiaxial Stress States. In the model the mean Stress effect has been considered. The LCF life model is based on the crystallographic theory. The LCF life is a power function of maximum resolved shear Stress of the activated slip systems. Further, the mean Stress effects are taken into consideration. The LCF model parameters can be obtained from smooth round specimens at different Stress levels. The LCF life model has first been validated for another smooth round specimens. Six further notched round specimens (U-type and V-type notches) have been studied to validate the LCF life model. Next, the parameters obtained from the two smooth round specimens mentioned above have been applied. Good agreement has been obtained with experimental results. The results are supported further by the SEM check on the fracture surfaces. The deformation mechanisms of nickel-based single-crystal superalloys DD3 under Multiaxial Stress State were discussed briefly.

Xueping Mao - One of the best experts on this subject based on the ideXlab platform.

  • Research on hardness variation for P92 notched specimen creep experiment
    Materials at High Temperatures, 2018
    Co-Authors: Xiang Lan, Ni Yongzhong, Xueping Mao
    Abstract:

    In order to study the hardness variation of P92 steel during creep in Multiaxial Stress State, creep experiments of specimens with various notches were conducted under different Stresses at 650°C. The hardness and microstructure changes were investigated after creep experiments. The factors related to the hardness of P92 steel notched specimens were discussed. The Kachanov-Robotnov constitutive model for the creep of P92 steel was used to calculate the Stress State and damage of P92 steel notched specimens during creep. The results showed that the hardness of P92 steel notched specimens decreased with the decrease of Stress level and the increase of Multiaxiality. The relationship among hardness, secondary phase precipitates, Multiaxiality and damage were discussed.

  • Study on creep mechanical behaviour of P92 steel under Multiaxial Stress State
    Materials at High Temperatures, 2015
    Co-Authors: Xiang Lan, Xueping Mao
    Abstract:

    The creep mechanical behaviour of P92 steel at 650°C has been studied by experimental research and finite element analysis. During the creep of P92 steel, there existed the notched strengthening effect, which was influenced by the shapes of the notch and the nominal Stress. Under the condition of the same notch depth, the creep life enhancement factor increased with decreasing notched radius or the increase of Stress. The Multiaxial Stress caused by the notch effect had a significant influence on the evolution of the microstructure and resulted in a transforming tendency from ductile to brittle at the root of the notch. The fracture position varied with the shapes of the notch: the U shaped notch started to fracture at the root of the notch, while the C shaped notch in the centre of the specimen. The creep process of notched specimens was simulated by embedding Kachanov–Rabotnov creep damage constitutive model into the interface program of finite element software. The result showed that damage distributio...

  • Analysis on Fracture Mechanism of T92 Steel under High Temperature Multiaxial Creep
    Advanced Materials Research, 2014
    Co-Authors: Jun Yuan, Xiao Wang, Sai Dong Huang, Jing Liu, Xueping Mao
    Abstract:

    The high temperature creep tests of standard specimen and double U-notched specimen of T92 steel were carried out under different Stresses at 600°C and 650 °C. Then scanning electron microscopy was used to observe the fracture morphology. The results show that the notch weakens plasticity, and weakening with the notch acuity. Under Multiaxial Stress State, the failure mode of T92 steel gradually transfers from ductile dimple to brittle quasi-cleavage fracture. Compared with uniaxial Stress State, the dimples under Multiaxial Stress State are smaller and shallower, within lots of carbides and second phase particles. The notch slows the connection, growth and gather of microvoids, and exhibits notch strengthening effect.

  • Study on Creep Behaviors of T92 Steel under Multiaxial Stress State
    Advanced Materials Research, 2013
    Co-Authors: Xueping Mao, Sai Dong Huang
    Abstract:

    Creep tests for smooth specimens and notched specimens of T92 steel were carried out to study the effect of Multiaxial Stress State on creep rupture behaviors at 650°C. Creep rupture life was estimated by representative Stress at Multiaxial State of Stress, the failure behavior of Multiaxial creep was analyzed, and Kachanov creep damage formula was used to analyze the experimental data. The results show that the notch strengthens rupture life, Multiaxial rupture behavior is controlled by mixed parameters, the creep ductility of the smooth and notched specimen decreases with rupture time, and damage factors of the smooth specimen and notched specimen are similar according to Kachanov formula.

  • Analysis on Fracture Morphology and Microstructure of T92 Steel after High Temperature Multiaxial Creep
    Advanced Materials Research, 2013
    Co-Authors: Xueping Mao, Xiao Wang, Sai Dong Huang
    Abstract:

    The high temperature creep tests of standard specimen and double U-type notch specimen of T92 steel were carried out under different Stresses at 650 °C. Then optical microscopy and scanning electron microscopy were used to observe the fracture morphology and microstructure. The results show that the Multiaxial Stress State leads to the creep fracture cracking initiation in notch. Under Multiaxial Stress State, the failure mode of T92 steel is transgranular and dimple plastic fracture, and is more obvious with the increase of creep life. Compared with under uniaxial Stress State, the precipitates under Multiaxial Stress State are larger in size and quantity, and are much coarser.

Zhufeng Yue - One of the best experts on this subject based on the ideXlab platform.

  • Microstructure evolution mechanisms in nickel-based single crystal superalloys under Multiaxial Stress State
    Journal of Alloys and Compounds, 2019
    Co-Authors: Yamin Zhang, Zhixun Wen, Haiqing Pei, Zhao Yanchao, Zhufeng Yue
    Abstract:

    Abstract Thin-walled plate specimens with square and triangular penetration pattern close-packed film cooling holes are used to study the evolution of the γ/γ′-microstructure of nickel-based single crystal superalloys during [001] orientation tensile creep. For both types of penetration patterns, the creep tests were performed at ligament efficiencies of 0.4 and 0.8 at 980 °C and a net section Stress of 300 MPa. In contrast, the creep experiment of specimens with square penetration pattern film cooling holes at a ligament efficiency of 0.8 at 1050 °C was also carried out. Quantitative metallographic assessment is used to investigate the influence of the Multiaxial Stress State on the microstructural evolution of nickel-based single crystal superalloys. The results show that the evolution of the γ/γ′-microstructure in specimens with square and triangular penetration pattern film cooling holes is related to the kinetics of the Stress redistribution during tensile creep. A minimum Stress level is necessary for rafting to occur at a specific experimental temperature. The contrast between the mechanical results and microstructural findings shows the effect of the maximum principal Stress and Stress triaxiality on the microstructural evolution of nickel-based single crystal superalloy specimens with close-packed film cooling holes. The rafting orientation of the γ/γ′-microstructure is shown to be sensitive to the direction of the maximum principal Stress. Finally, the γ/γ′ topological inversion is faster under higher ligament efficiency.

  • Creep damage mechanism and γ′-phase morphology of a V-notched round bar in Ni-based single crystal superalloys
    Materials Science and Engineering: A, 2014
    Co-Authors: D.s. Liu, Zhixun Wen, Zhufeng Yue
    Abstract:

    Abstract The circumferential V-type notched specimen has been designed to investigate the effect of Multiaxial Stress State on creep rupture behavior of Ni-based single crystal superalloys at 980 °C. The Stress on the minimum net-section is chosen to be 400 MPa. Tests on smooth specimens were also carried out under 400 MPa for comparison. Time to creep fracture was found to be higher in the notched specimens. Scanning Electrical Microscope (SEM) analysis indicated that rupture initiates at the notch root in the notched specimen and at the inner in the smooth specimen. Finite element analysis was carried out to understand the Stress distribution and the creep damage evolution under Multiaxial Stress State. The morphology the evolution of γ′-phase proved that directional coarsening was strongly dependent on the local principal Stress field. These findings can be helpful to understand the effect of notch on the creep rupture behavior and mechanism, especially on the γ′-phase morphology evolution.

Lucien Laiarinandrasana - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Multiaxial Stress State on Morphology and Spatial Distribution of Voids in Deformed Semicrystalline Polymer Assessed by X-ray Tomography
    Macromolecules, 2012
    Co-Authors: Lucien Laiarinandrasana, Thilo F. Morgeneyer, Henry Proudhon, Franck N'guyen, Eric Maire
    Abstract:

    Cavitation in the semicrystalline polymer polyamide 6 has been studied in terms of 3D void morphology and distribution in the notched region of axisymmetric specimens using synchrotron radiation tomography at submicrometer resolution. Ex-situ (interrupted and unloaded) tests at different stages of straining reveal damage initiation in form of penny-shaped crazes at maximum load. An in-situ (under load) test confirms the damage morphology at maximum load. When a neck appears and extends within the notch, the penny-shaped crazes extend in height, resulting in a volume change. Final failure is seen to occur from the specimen interior via coalescence of several voids resulting in large cavities. The Multiaxial Stress State generated by the axisymmetric notch causes crazes/cracks that are larger in diameter than those occurring during necking of an initially smooth specimen. The distribution void volume fraction as a function of the radius is measured via image analysis, showing a damage maximum at the specimen center that decreases toward the specimen border. This distribution was found to be consistent with that of the Stress triaxiality ratio.

  • Multiaxial Stress State assessed by 3D X-Ray tomography on semi-crystalline polymers
    Optical Measurements Modeling and Metrology Volume 5, 2011
    Co-Authors: Lucien Laiarinandrasana, Thilo F. Morgeneyer, Henry Proudhon
    Abstract:

    This work aims at linking the microstructural evolution of semi-crystalline polymers to the macroscopic material behaviour under Multiaxial Stress State. Tensile tests on notched round bars, interrupted after different stages of deformation before failure, were supposed to have undergone various States of Stress in the vicinity of the net cross-section. They were examined using synchrotron radiation tomography. A sample obtained from a test stopped at the end of Stress softening stage showed elongated axi-symmetric columns of voids separated by thin ligaments of material. This special morphology allowed investigating the distributions of voids in terms of both volume fraction and orientation. This distribution was compared with the theoretical Multiaxial Stress/strain field. The combination of the tomographic images analyses and the continuum mechanics approach results in a determination of the principal mechanical parameter driving voids evolution.