The Experts below are selected from a list of 11109 Experts worldwide ranked by ideXlab platform
Shinichi Komazaki - One of the best experts on this subject based on the ideXlab platform.
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application of small punch Creep Testing for evaluation of Creep properties of as received and artificially aged 5cr 0 5mo steel
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2018Co-Authors: Arturo Ortizmariscal, M L Saucedomunoz, Shinichi KomazakiAbstract:Abstract The small punch Creep Testing method was applied to evaluate the Creep properties for the as-received and artificially aged 5Cr-0.5Mo steel. The small punch Creep test was conducted at 600 °C using loads between 67 and 100 N and specimen size of 3 mm diameter and 0.25 mm thickness under an argon gas atmosphere. In order to study the effect of aging on Creep properties, steel specimens were aged at 600 °C for up to 6000 h. The small punch Creep curves indicated that the time to rupture decreased and minimum Creep rate increased with Testing load. The aging process of steel specimens caused the decrease in time to rupture with increasing aging time, which can be attributed to the increase in size and the decrease in number density of precipitates with aging time. The load-equivalent stress ratio was determined to be about 0.49 by finite element method for the as-received steel. In contrast, the load-stress ratio was found to be 0.63 for the experimental SP Creep and uniaxial Creep test results. However, the best relationship between stress and time to rupture was obtained for the experimental ratio of 0.63.
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evaluation of Creep rupture strength of high nitrogen ferritic heat resistant steels using small punch Creep Testing technique
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2016Co-Authors: Shinichi KomazakiAbstract:Abstract The development of next generation ultra-heat-resistant ferritic steels for the future advanced thermal power plants which operate in excess of 700 °C are currently in progress in Japan. The small punch (SP) Creep Testing technique which uses miniature specimens has been applied to evaluate Creep rupture strength of newly developed high nitrogen ferritic steels. The SP Creep tests have been carried out on different grades of high nitrogen ferritic steels in the temperature range of 600–800 °C, under different loads in the range of 70–400 N, using specimens of dimension ∅8 mm x 0.5 mm. The SP Creep rupture results of high nitrogen ferritic steels have been compared with that of conventional steel (Gr.91). The high nitrogen steels exhibited higher Creep rupture strength when compared to the Gr.91. The Creep rupture results obtained from SP Creep tests were correlated to the uniaxial Creep rupture results obtained from conventional Creep tests using a stress conversion coefficient of 2.05. The paper investigates the applicability of SP Creep Testing technique for the evaluation of Creep rupture strength of high nitrogen ferritic heat-resistant steels.
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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, 2016Co-Authors: Toshiya Nakata, Shinichi Komazaki, Yutaka Kohno, Hiroyasu TanigawaAbstract: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.
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Creep property measurement of service exposed sus 316 austenitic stainless steel by the small punch Creep Testing technique
Journal of Materials Research, 2002Co-Authors: Maribel L Saucedomunoz, Shinichi Komazaki, Toru Takahashi, Toshiyuki Hashida, Tetsuo ShojiAbstract:The Creep properties for SUS 316 HTB austenitic stainless steel were evaluated by using the small-punch Creep test at 650 °C for loads of 234, 286, 338, 408, and 478 N and at 700 °C for loads of 199 and 234 N. The Creep curves, determined by means of the small-punch Creep test, were similar to those obtained from a conventional uniaxial Creep test. That is, they exhibited clearly the three Creep stages. The width of secondary Creep stage and rupture time t r decreased with the increase in Testing load level. The Creep rupture strength for the service-exposed material was lower than that of the as-received material at high Testing loads. However, the Creep resistance behavior was opposite at relatively low load levels. This difference in Creep resistance was explained on the basis of the difference in the Creep deformation and microstructural evolution during tests. It was also found that the ratio between the load of small-punch Creep test and the stress of uniaxial Creep test was about 1 for having the same value of Creep rupture life.
K Milicka - One of the best experts on this subject based on the ideXlab platform.
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application of Creep small punch Testing in assessment of Creep lifetime
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2009Co-Authors: Ferdinand Dobes, K MilickaAbstract:Abstract In this contribution, the problem is investigated, whether the dependence of the time to rupture on the acting force in small punch tests can be analyzed in the same way as the dependence of time to rupture on the applied stress in conventional tensile Creep tests. Two comparable sets of constant-force small punch tests and relevant conventional Creep tests on P91 steel were performed at temperatures from 823 to 873 K. The experimental results were analyzed using various parametric approaches (Larsson–Miller, Fisher–Dorn, etc.) very well-known from conventional Creep Testing. It is shown that the methods based on time–temperature parameter can be used also for a description of small punch test data. The differences among various studied methods are negligible; the best description can be achieved with the Sud–Aviation parameter. The extrapolated data can be used for determination of empirical relationships between stress and minimum Creep rate in the Creep tests and force and minimum deflection rate in the small punch test.
G Eggele - One of the best experts on this subject based on the ideXlab platform.
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high temperature strength and damage evolution in short fiber reinforced aluminum alloys studied by miniature Creep Testing and synchrotron microtomography
Acta Materialia, 2012Co-Authors: D Kurumlu, E J Payto, Marcus L Young, M Schobel, Guillermo Requena, G EggeleAbstract:Abstract The Creep behavior of a squeeze-cast, short fiber reinforced Al metal matrix composite (MMC), consisting of an Al–11 wt.% Zn–0.2 wt.% Mg alloy reinforced with 15 vol.% Al 2 O 3 Saffil® short fibers is investigated using miniature Creep specimens. The small dimensions of the miniature Creep specimens permit them to be machined from regions of an MMC block with different microstructures, thus allowing the effect of grain size and fiber texture on Creep to be investigated on a more local level than is possible using conventional specimen geometries. The miniature Creep specimens are subjected to uniaxial tensile stresses ranging from 3 to 40 MPa at temperatures between 573 and 623 K. It is shown that tests performed using the miniature Creep specimen geometry are in good agreement with results previously obtained with standard Creep specimens. Through interrupted Creep experiments, it is observed that the Creep back flow that occurs after unloading increases with increasing accumulated plastic strain. In the as-cast MMC, synchrotron microtomography reveals a fine distribution of pores whose spatial density increases with the spatial density of the fibers. The presence of fractured fibers in the crept MMC is also revealed. Some of the regions between fractured fiber fragments appear to be filled with matrix material, while others are voided.
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Creep of a tial alloy a comparison of indentation and tensile Testing
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2003Co-Authors: Dorothee Dorne, Klaus Rolle, Irgi Skrotzki, Ernhard Stockhe, G EggeleAbstract:Abstract The present study compares the indentation and uniaxial Creep behaviour of a near-γ-TiAl alloy with a duplex microstructure. Indentation Creep tests were performed using a cylindrical indenter at temperatures between 750 and 1050 °C and net section stresses between 50 and 1430 MPa. A stress dependent stress exponent ranging from 3 for low net section stresses to 8 for high net section stresses was determined. The apparent activation energy of indentation Creep was determined as 343±16 kJ mol −1 . The stress as well as the temperature dependence of the indentation and uniaxial Creep data are in good agreement. The indentation experiments were also analysed with respect to the deformed volume in front of the indenter and the surface bulge that develops around the indenter. A simple dislocation model is proposed to rationalize volume and shape of the bulge around the indenter. The good agreement of Creep parameters obtained by indentation and conventional uniaxial Creep Testing demonstrates that indentation Creep tests are suitable to characterize Creep.
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double shear Creep Testing of superalloy single crystals at temperatures above 1000 c
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 1995Co-Authors: C May, G Eggele, G A Webste, G PeteAbstract:Abstract The present paper describes a technique for double sher Creep Testing of superalloy single crystals (SX) at temperatures above 1000 °C. From an engineering point of view this method is interesting because shear Testing represents a simple case of multiaxial loading and because Creep anisotropy can be easily assessed. In the case of SXs pure shear loading allows to directly activate specific crystallographic slip systems and this makes the method attractive from a fundamental point of view. The paper highlights all important experimental aspects which must be considered in the development of a double shear test. In addition finite element Creep calculations were performed to study shear and bending stresses for isotropic material behaviour. Preliminary mechanical and microstructural results, which show the viability of the technique are presented.
Tetsuo Shoji - One of the best experts on this subject based on the ideXlab platform.
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development of heat resistant fe based alloys for a usc steam boiler using ultra high purity uhp technology
Corrosion Science, 2018Co-Authors: Fethi Hamdani, Tetsuo ShojiAbstract:Abstract The design of ultra-high purity (UHP) Fe-based alloys for advanced ultra-supercritical (A-USC) technology is suggested in this work. The Creep Testing at 700 °C and a stress level of 150 MPa have been performed in air. The addition of small amount of reactive-elements, W, Nb, Zr and Sc, has been undertaken into model alloys with the intention to promote the precipitation strengthening. Optimizing the chemical composition coupled by pre-straining enabled improving the Creep resistance; hence a Creep-rupture life of 750 h was reached. The oxidation resistance in supercritical water is remarkably enhanced by small addition of Sc.
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Creep property measurement of service exposed sus 316 austenitic stainless steel by the small punch Creep Testing technique
Journal of Materials Research, 2002Co-Authors: Maribel L Saucedomunoz, Shinichi Komazaki, Toru Takahashi, Toshiyuki Hashida, Tetsuo ShojiAbstract:The Creep properties for SUS 316 HTB austenitic stainless steel were evaluated by using the small-punch Creep test at 650 °C for loads of 234, 286, 338, 408, and 478 N and at 700 °C for loads of 199 and 234 N. The Creep curves, determined by means of the small-punch Creep test, were similar to those obtained from a conventional uniaxial Creep test. That is, they exhibited clearly the three Creep stages. The width of secondary Creep stage and rupture time t r decreased with the increase in Testing load level. The Creep rupture strength for the service-exposed material was lower than that of the as-received material at high Testing loads. However, the Creep resistance behavior was opposite at relatively low load levels. This difference in Creep resistance was explained on the basis of the difference in the Creep deformation and microstructural evolution during tests. It was also found that the ratio between the load of small-punch Creep test and the stress of uniaxial Creep test was about 1 for having the same value of Creep rupture life.
Ferdinand Dobes - One of the best experts on this subject based on the ideXlab platform.
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tensile and Creep Testing of sanicro 25 using miniature specimens
Materials, 2018Co-Authors: Pe Dymacek, Mila Jarý, Ferdinand Dobes, Lubos KlocAbstract:Tensile and Creep properties of new austenitic steel Sanicro 25 at room temperature and operating temperature 700 °C were investigated by Testing on miniature specimens. The results were correlated with Testing on conventional specimens. Very good agreement of results was obtained, namely in yield and ultimate strength, as well as short-term Creep properties. Although the Creep rupture time was found to be systematically shorter and Creep ductility lower in the miniature test, the minimum Creep rates were comparable. The analysis of the fracture surfaces revealed similar ductile fracture morphology for both specimen geometries. One exception was found in a small area near the miniature specimen edge that was cut by electro discharge machining, where an influence of the steel fracture behavior at elevated temperature was identified.
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application of Creep small punch Testing in assessment of Creep lifetime
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2009Co-Authors: Ferdinand Dobes, K MilickaAbstract:Abstract In this contribution, the problem is investigated, whether the dependence of the time to rupture on the acting force in small punch tests can be analyzed in the same way as the dependence of time to rupture on the applied stress in conventional tensile Creep tests. Two comparable sets of constant-force small punch tests and relevant conventional Creep tests on P91 steel were performed at temperatures from 823 to 873 K. The experimental results were analyzed using various parametric approaches (Larsson–Miller, Fisher–Dorn, etc.) very well-known from conventional Creep Testing. It is shown that the methods based on time–temperature parameter can be used also for a description of small punch test data. The differences among various studied methods are negligible; the best description can be achieved with the Sud–Aviation parameter. The extrapolated data can be used for determination of empirical relationships between stress and minimum Creep rate in the Creep tests and force and minimum deflection rate in the small punch test.