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Volume 34 (1996)
- Issue 6 Pages 348-
- Issue 5 Pages 284-
- Issue 4 Pages 212-
- Issue 3 Pages 118-
- Issue 2 Pages 58-
- Issue 1 Pages 3-
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Volume 34, Issue 5
Displaying 1-7 of 7 articles from this issue
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Hiroshi MIMURA, Hironori NAGAI, Kouji ISHIKAWA1996 Volume 34 Issue 5 Pages 284-291
Published: September 25, 1996
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSFor various kinds of matrix-microstructure, embrittlement by high carbon martensite islands (M*) was evaluated as the difference of the transition temperatures between two specimens; one specimen holding M* and the other containing no M*. The transition temperatures were measured for CTOD test, the standard Charpy test and the press notched Charpy test. The results are summarized as follows.
(1) The embrittlement by M* in CTOD depends on the matrix-microstructure through the M* size. Lower bainite has smaller M* size and less susceptibility to M* embrittlement than other microstructures.
(2) The embrittlement by M* in CTOD was remarkable in comparison with those of the other tests for the mixed microstructure of ferrite and upper bainite, while all test gave the similar embrittlement for specimens of ferrite-pearlite or martensite, i.e. the uniform microstructure.View full abstractDownload PDF (3109K) -
Toshitaro MIMAKI, Susumu MIZUNUMA, Genki YAGAWA1996 Volume 34 Issue 5 Pages 292-304
Published: September 25, 1996
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSCreep-rupture strength and creep strain curve are popularly evaluated by TTP method and θ projection concept, respectively, where TTP method can extrapolate creep-rupture data by a TTP function compensating temperature difference and polynomial of stress, and θ method, one of unsteady creep constitutive equations, predicts creep strain curve including the tertiary stage. However, the parameter estimation procedures for the conventional methods have some statistical and numerical difficulties e. g., inversion of the creep-rupture curve, nonconvergence and so on.
In order to improve the accuracy of estimation and to eliminate these difficulties, the authors have proposed two parameter estimation procedures employing nonlinear programming. One is for TTP method and another is for θ projection concept.
According to estimation examples from calculated data referring to literatures and experimental data, these procedures can successfully predict the creep-rupture strength and the creep strain curve obtained for some steels.View full abstractDownload PDF (1474K) -
Hiroshi MIMURA, Yasutoshi HIRAMOTO, Hiroyuki YAMAGUCHI1996 Volume 34 Issue 5 Pages 305-311
Published: September 25, 1996
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSMetallurgical factors controlling COA were studied, by using plain carbon steels of various strength levels. The results are summarized as follows. (1) COA decreases with increase in hardness, amount of inclusion, size of precipitate and amount of low temperature transformation product. (2) Anisotropy of COA, i.e. the ratio of COA in a specimen of L-direction to that of T-direction, comes from inclusion, and texture. (3) COA has fairly good correlation with Charpy absorbed energy of the full ductile fracture mode.View full abstractDownload PDF (3481K) -
Asao OKAMOTO, Yukinori YAMAMOTO, Seiji ASADA1996 Volume 34 Issue 5 Pages 312-319
Published: September 25, 1996
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSRound robin calculations of collapse loads for a pressure vessel were made by sixteen teams in Japan. The model is composed of a cylinder and a head including spherical, conical, and tons segments. The structure is an example to which the stress classifications specified in the ASME Code are not strictly applicable.
The calculations were performed to clarify the issue of the evaluation procedure using the limit analysis method specified in the ASME Section III, and to check the sensitivity of the calculation models and programs. It is found that the stress at knuckle region has certain characteristic of secondary stress, but still dominates the collapse of the vessel. It is recommendable to use limit analysis to prove the validity of the stress classification.
The sensitivity of the calculation methods was not so significant. Thereby it is concluded that the limit analysis can be used as a standard procedure in regulation.View full abstractDownload PDF (756K) -
Masaaki MATSUBARA, Toshihiro AYABE, Kohji BUSUJIMA, Kenji SAKAMOTO, Ya ...1996 Volume 34 Issue 5 Pages 320-327
Published: September 25, 1996
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSStrength degradation was observed during proof testing in ceramic materials due to slow crack growth (S. C. G.). An experimental setup, a pressure vessel-type proof testing system, was developed in order to investigate this strength degradation. After proof testing, specimens for four-point bending tests were cut from the so-called strength-guaranteed area within which equivalent stress is higher than 90 percent of the maximum one. Fracture stress was measured at room temperature for each specimen. Furthermore, the predicted fracture is represented in terms of failure probability based on G-criterion. Good agreement between experimental and theoretical data was achieved.View full abstractDownload PDF (838K) -
Yasuhiro IWASAKI, Akira UI1996 Volume 34 Issue 5 Pages 328-334
Published: September 25, 1996
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSIn capsule free sinter-HIPping of Al2O3, the effects of timing of pressurizing in various HIP parameters on properties of sintered products were especially investigated.
The experiments were conducted with various temperatures in pressureless presintering and the timings of pressurizing in HIP process. For the samples sintered by the capsule free HIP method, density, bending strength and fracture toughness were measured, and it was confirmed that the timing of pressurizing in HIP process was an important facter in order to attain the high density of Al2O3.View full abstractDownload PDF (2304K) -
Yuzuru SAKAI, Kohei NOMA, Hiroshi OHYA, Hiroshi WADA1996 Volume 34 Issue 5 Pages 335-341
Published: September 25, 1996
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSIn order to clarify the crack growth behaviors in the glass fiber reinforced plastic (GFRP) plates, the experimental investigations were performed with the aid of a AE system. The tension specimens made by three types of glass fiber cloths (Woven Roving, Glass Cloth and Chopped Strandmat) were monotonically loaded and the glowth of a surface crack were recorded by a video camera. It was cleared that the crack growth behavior of GFRP plates were particularly different in the types of fiber cloths and the volume fractions.View full abstractDownload PDF (2975K)
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