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Hiroyasu Tanigawa - One of the best experts on this subject based on the ideXlab platform.

  • development of a small punch testing method to evaluate the creep property of high cr ferritic steel part i effect of Atmosphere on creep deformation behavior
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2016
    Co-Authors: Toshiya Nakata, Shin-ichi Komazaki, Yutaka Kohno, Hiroyasu Tanigawa
    Abstract:

    Abstract In a preliminary study carried out for evaluating creep properties with the small punch (SP) creep testing method, creep tests were performed using reduced activation ferritic/martensitic steel (RAFMs) F82H specimens both in an Argon Atmosphere and in vacuum (less than 10−3 Pa). The results showed that the rupture time was approximately 2.5 times longer in the Argon Atmosphere compared to that in the vacuum. Changes in the deflection rate with the deflection and time and changes in the minimum creep deflection rate with the rupture time were almost independent of the test Atmosphere, although the minimum creep deflection rate decreased as the rupture time increased. After comparing the SP creep test results, which were sorted by using the Larson-Miller parameter, and the standard creep test results, the ratio (F/σ) between the load (F) in the SP creep test and the stress (σ) in the standard creep test was determined to be 2.1 and 2.3 for the Argon Atmosphere and vacuum, respectively. Consequently, it was found that the ratio, namely, the load/stress conversion coefficient, depended on the test Atmosphere. This result implied that the stress and/or strain distribution on the SP specimen varied with the type of Atmosphere. This change with the test Atmosphere seemed to be closely associated with changes in the friction between the specimen and the ball.

  • development of a small punch testing method to evaluate the creep property of high cr ferritic steel part ii stress analysis of small punch test specimen by finite element method
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2016
    Co-Authors: Toshiya Nakata, Shin-ichi Komazaki, Yutaka Kohno, Hiroyasu Tanigawa
    Abstract:

    Abstract From the creep rupture data for the reduced activation ferritic/martensitic steel F82H, the ratio between the load in the small punch (SP) creep test and the stress in the standard creep test is estimated to be 2.1 in an Argon Atmosphere and 2.3 in a vacuum. However, the reasons for the difference between the values of stress conversion coefficients and the physical meaning of these values have not been clarified. In this study, stress analyses of SP creep specimens were carried out for F82H by using finite element analysis to clarify the physical meaning of the stress conversion coefficient. The friction coefficient between the ball and specimen affected the SP creep properties, and an increase in the friction coefficient resulted in an increase in the rupture time. The applied load (F) and the averaged equivalent stress in the steady state (σs) correlated linearly, and the increasing friction coefficient tended to decrease σs. It was possible to replicate the test results obtained in the Argon Atmosphere with a friction coefficient of 0.39 and the results obtained in the vacuum with a friction coefficient of 1.3. It was also found that the SP creep test results, which were determined by σs, agree well with the standard creep test results.

Toshiya Nakata - One of the best experts on this subject based on the ideXlab platform.

  • development of a small punch testing method to evaluate the creep property of high cr ferritic steel part i effect of Atmosphere on creep deformation behavior
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2016
    Co-Authors: Toshiya Nakata, Shin-ichi Komazaki, Yutaka Kohno, Hiroyasu Tanigawa
    Abstract:

    Abstract In a preliminary study carried out for evaluating creep properties with the small punch (SP) creep testing method, creep tests were performed using reduced activation ferritic/martensitic steel (RAFMs) F82H specimens both in an Argon Atmosphere and in vacuum (less than 10−3 Pa). The results showed that the rupture time was approximately 2.5 times longer in the Argon Atmosphere compared to that in the vacuum. Changes in the deflection rate with the deflection and time and changes in the minimum creep deflection rate with the rupture time were almost independent of the test Atmosphere, although the minimum creep deflection rate decreased as the rupture time increased. After comparing the SP creep test results, which were sorted by using the Larson-Miller parameter, and the standard creep test results, the ratio (F/σ) between the load (F) in the SP creep test and the stress (σ) in the standard creep test was determined to be 2.1 and 2.3 for the Argon Atmosphere and vacuum, respectively. Consequently, it was found that the ratio, namely, the load/stress conversion coefficient, depended on the test Atmosphere. This result implied that the stress and/or strain distribution on the SP specimen varied with the type of Atmosphere. This change with the test Atmosphere seemed to be closely associated with changes in the friction between the specimen and the ball.

  • development of a small punch testing method to evaluate the creep property of high cr ferritic steel part ii stress analysis of small punch test specimen by finite element method
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2016
    Co-Authors: Toshiya Nakata, Shin-ichi Komazaki, Yutaka Kohno, Hiroyasu Tanigawa
    Abstract:

    Abstract From the creep rupture data for the reduced activation ferritic/martensitic steel F82H, the ratio between the load in the small punch (SP) creep test and the stress in the standard creep test is estimated to be 2.1 in an Argon Atmosphere and 2.3 in a vacuum. However, the reasons for the difference between the values of stress conversion coefficients and the physical meaning of these values have not been clarified. In this study, stress analyses of SP creep specimens were carried out for F82H by using finite element analysis to clarify the physical meaning of the stress conversion coefficient. The friction coefficient between the ball and specimen affected the SP creep properties, and an increase in the friction coefficient resulted in an increase in the rupture time. The applied load (F) and the averaged equivalent stress in the steady state (σs) correlated linearly, and the increasing friction coefficient tended to decrease σs. It was possible to replicate the test results obtained in the Argon Atmosphere with a friction coefficient of 0.39 and the results obtained in the vacuum with a friction coefficient of 1.3. It was also found that the SP creep test results, which were determined by σs, agree well with the standard creep test results.

Srinivasa T Rao - One of the best experts on this subject based on the ideXlab platform.

  • effect of sintering Atmosphere on structure and properties of austeno ferritic stainless steels
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2009
    Co-Authors: R Mariappan, S Kumaran, Srinivasa T Rao
    Abstract:

    Abstract Prealloyed 316L and 430L stainless steel powders along with Cu, Cr, Mo and Ni have been used to produce different austeno-ferritic stainless steels through powder metallurgy route. Cylindrical green compacts of 30 mm diameter and 12 mm height have been made at three different compaction pressures and sintered in nitrogen and Argon Atmospheres at 1350 °C for 4 h, to study the effect of sintering on densification behaviour and mechanical properties. Stainless steels sintered in Argon Atmosphere exhibited better densification rate than the nitrogen Atmosphere sintering. The microstructure of stainless steel sintered in nitrogen Atmosphere revealed lamellar constituents with grain boundary Cr2N in ferritic matrix. Composition A (50 wt% 316L + 50 wt% 430L) of austeno-ferritic stainless steel sintered in Argon Atmosphere showed bi-phase structure with high strength and better elongation. The XRD patterns are in line with the microstructure. The ferrite content was measured by ferrite scope and is coherent with the strength and structures.

Zhangfa Tong - One of the best experts on this subject based on the ideXlab platform.

  • Nonisothermal Decomposition Kinetics of Abietic Acid in Argon Atmosphere
    2016
    Co-Authors: Wei Jian Nong, Xiao Peng Chen, Jie Zhen Liang, Linlin Wang, Lingping Zhong, Zhangfa Tong
    Abstract:

    Abietic acid was isolated from rosin by means of reaction-crystallization coupled with exposure to ultrasonic waves, and it was then characterized by its specific rotation, infrared spectra, and 13C nuclear magnetic resonance spectra. The thermal decomposition of abietic acid in Argon Atmosphere was studied under nonisothermal conditions using TG-DTG techniques with heating rates of 5, 10, 20, and 25 K/min. For the kinetic study, the nonisothermal kinetic parameters were obtained via the analysis of the TG-DTG curves by using the Flynn-Wall-Ozawa (FWO) method, the Kissinger method, and the integral method. The results showed that the nonisothermal decomposition mechanism of abietic acid in Argon Atmosphere followed Mampel Power law with n = 3/2, whose differential and integral forms were f(α) = 2/3α–1/2 and G(α) = α3/2. The apparent activation energy Ea and the pre-exponential factor A were 123.44 kJ/mol and 1.78 × 1011 s–1, respectively. The kinetic equation can be expressed as dα/dt = 1.19 × 1011 α–1/2 exp(−1.48 × 104/T). The thermodynamic parameters (ΔH⧧, ΔG⧧, and ΔS⧧) were calculated as well

  • nonisothermal decomposition kinetics of abietic acid in Argon Atmosphere
    Industrial & Engineering Chemistry Research, 2011
    Co-Authors: Wei Jian Nong, Xiao Peng Chen, Jie Zhen Liang, Linlin Wang, Lingping Zhong, Zhangfa Tong
    Abstract:

    Abietic acid was isolated from rosin by means of reaction-crystallization coupled with exposure to ultrasonic waves, and it was then characterized by its specific rotation, infrared spectra, and 13C nuclear magnetic resonance spectra. The thermal decomposition of abietic acid in Argon Atmosphere was studied under nonisothermal conditions using TG-DTG techniques with heating rates of 5, 10, 20, and 25 K/min. For the kinetic study, the nonisothermal kinetic parameters were obtained via the analysis of the TG-DTG curves by using the Flynn-Wall-Ozawa (FWO) method, the Kissinger method, and the integral method. The results showed that the nonisothermal decomposition mechanism of abietic acid in Argon Atmosphere followed Mampel Power law with n = 3/2, whose differential and integral forms were f(α) = 2/3α–1/2 and G(α) = α3/2. The apparent activation energy Ea and the pre-exponential factor A were 123.44 kJ/mol and 1.78 × 1011 s–1, respectively. The kinetic equation can be expressed as dα/dt = 1.19 × 1011α–1/2 e...

Yutaka Kohno - One of the best experts on this subject based on the ideXlab platform.

  • development of a small punch testing method to evaluate the creep property of high cr ferritic steel part i effect of Atmosphere on creep deformation behavior
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2016
    Co-Authors: Toshiya Nakata, Shin-ichi Komazaki, Yutaka Kohno, Hiroyasu Tanigawa
    Abstract:

    Abstract In a preliminary study carried out for evaluating creep properties with the small punch (SP) creep testing method, creep tests were performed using reduced activation ferritic/martensitic steel (RAFMs) F82H specimens both in an Argon Atmosphere and in vacuum (less than 10−3 Pa). The results showed that the rupture time was approximately 2.5 times longer in the Argon Atmosphere compared to that in the vacuum. Changes in the deflection rate with the deflection and time and changes in the minimum creep deflection rate with the rupture time were almost independent of the test Atmosphere, although the minimum creep deflection rate decreased as the rupture time increased. After comparing the SP creep test results, which were sorted by using the Larson-Miller parameter, and the standard creep test results, the ratio (F/σ) between the load (F) in the SP creep test and the stress (σ) in the standard creep test was determined to be 2.1 and 2.3 for the Argon Atmosphere and vacuum, respectively. Consequently, it was found that the ratio, namely, the load/stress conversion coefficient, depended on the test Atmosphere. This result implied that the stress and/or strain distribution on the SP specimen varied with the type of Atmosphere. This change with the test Atmosphere seemed to be closely associated with changes in the friction between the specimen and the ball.

  • development of a small punch testing method to evaluate the creep property of high cr ferritic steel part ii stress analysis of small punch test specimen by finite element method
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2016
    Co-Authors: Toshiya Nakata, Shin-ichi Komazaki, Yutaka Kohno, Hiroyasu Tanigawa
    Abstract:

    Abstract From the creep rupture data for the reduced activation ferritic/martensitic steel F82H, the ratio between the load in the small punch (SP) creep test and the stress in the standard creep test is estimated to be 2.1 in an Argon Atmosphere and 2.3 in a vacuum. However, the reasons for the difference between the values of stress conversion coefficients and the physical meaning of these values have not been clarified. In this study, stress analyses of SP creep specimens were carried out for F82H by using finite element analysis to clarify the physical meaning of the stress conversion coefficient. The friction coefficient between the ball and specimen affected the SP creep properties, and an increase in the friction coefficient resulted in an increase in the rupture time. The applied load (F) and the averaged equivalent stress in the steady state (σs) correlated linearly, and the increasing friction coefficient tended to decrease σs. It was possible to replicate the test results obtained in the Argon Atmosphere with a friction coefficient of 0.39 and the results obtained in the vacuum with a friction coefficient of 1.3. It was also found that the SP creep test results, which were determined by σs, agree well with the standard creep test results.