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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-
Predecessor
Volume 34, Issue 4
Displaying 1-7 of 7 articles from this issue
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Bonding Interface Microstrcuture of Zr/Stainless Steel by Hot Roll Bonding and its ControllingMasanori YASUYAMA, Kazuhiro OGAWA, Takao TAKA, Kazuyuki NAKASUJI, Yosh ...1996 Volume 34 Issue 4 Pages 212-221
Published: July 25, 1996
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSThe hot roll bonding of zirconium and stainless steel inserted with tantalium was investigated using the newly developed rolling mill. The effect of hot rolling temperatures of zirconium/stainless steel joints on bonding interface structure was evaluated. Intermetallic compound layer containing cracks was observed at the bonding interface between stainless steel and tantalium when the rolling temparature was above 1373K. The hardness of the bonding layer of zirconium and tantalium bonded above 1273K was higher than tantalium or zirconium base metal in spite of absence of intermetallic compound. The growth of reaction layer at the stainless steel and tantalium interface and at the tantalium and zirconium interface was comforming a parabolic low when that was isothermally heated after hot roll bonding, and the growth rate was almost same as that of static diffusion bonding without using hot roll bonding process. It is estimated that the strain caused by hot roll bonding gives no effectt on the growth of reaction layer. It was confirmed that the dissimilar joint of zirconium and stainless steel with insert of tantalium having the sound bonding interface were obtained at the suitable bonding temparature of 1173K by the usage of the newly developed hot roll bonding process.View full abstractDownload PDF (7592K) -
Yasuo OTOGURO, Masaaki MATSUBARA, Hidesato MABUCHI, Yukio TOMITA, Susu ...1996 Volume 34 Issue 4 Pages 222-230
Published: July 25, 1996
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSThe effects of heat treatment conditons on hydrogen attack and creep rupture properties in hydrogen were investigated with extra low carbon 17Ni martensitic steels.
The following results were obtained.
1) Microstructures of the steels were martensite and a small amount of austenite. Prior austenite grain boundaries were not clearly etched in the specimens as quenched.
2) Tensile strength and reduction of area after hydrogen exposure decreased and fracture occurred more intergranularly with increasing quenching temperature.
3) Deterioration of tensile properties after hydrogen exposure was more marked with the specimens tempered at 550°C than that with those as quenched for a steel containing 0.004%C and vice versa for a steel containing 0.045%C.
4) Creep rupture properties in hydrogen were better with decreasing quenching temperature. Tempering improved rupture strength and ductility.
5) Lower carbon content showed higher strength and ductility in both hydrogen attack and creep rupture tests in hydrogen.
6) It was proved that hydrogen decreased prior austenite grain boundary strength itself because quenching at higher temperature lowered rupture strength even in a steel containing only 0.004%C.View full abstractDownload PDF (7568K) -
Hiroshi MIMURA, Hiroshi SHIMANUKI, Junichi KOBAYASHI, Takayoshi OHSHIR ...1996 Volume 34 Issue 4 Pages 231-238
Published: July 25, 1996
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSA new model on the distribution of measured fracture toughness values in weld joints was proposed, by taking account of the fractographic observation that cleavage cracks started from the crack tip were often arrested after a little extension in COD test of the weld joints. The model can explain the wide scatter of the measured fracture toughness and existence of crack initiation sites other than the local brittle zone, which were often observed for the weld joint CTOD test in the past literatures.View full abstractDownload PDF (4185K) -
Hiroyuki SUMI, Kotoji ANDO, Kiichi TSUJI1996 Volume 34 Issue 4 Pages 239-247
Published: July 25, 1996
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSIn the past studies, the authors proposed that the criterion for obtaining the plane strain condition at the middle-section of the specimen was given by the following equation; B≥0.004 (Kc(J)/σys)2+0.01. However, there are some obscure points, such as the applicable region of Kc(J)/σys, in it. Therefore, fracture toughness tests were performed in the ductile-brittle transition temperature range and low-toughness temperature range for high strength steel (HT780).
The main results obtained were as followed. (1) For HT780, the results of the cleavage crack initiation sites and the fibrous crack shapes also showed the similar tendency with the former one.
(2)In the lower Kc(J)/σys region, the above-mentioned equation was not fit to the experimental results, (3) It is inferred that the stress in the thickness direction (σz) is distributed among the range which is decided by Sc and 1 /2Bc. (4) Therefore, becoming the plane strain with increasing the thickness, there will exist a transition state which can be the plane strain and the no-plane strain.View full abstractDownload PDF (3808K) -
Kyo Chul AHN, Seung Yo SON1996 Volume 34 Issue 4 Pages 249-255
Published: July 25, 1996
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSBolted joint in plastic region tightening acquire high tightening strength and high degree of efficiency of intensity. In case of high-cycle fatigue testing, a lot of time and efforts are needed to know correct data analysis and mathematical model. The S-N curve at a particular stress level represents the formation of the persistent slip band, its strain-hardening and crack formation (necking) and step-wise crack propagation locally in the test specimen. However, in the tensile test the whole specimen deforms plastically and strain-hardens homogeneously as the stress increases. Number of cycles to failure under cyclic loading depends only on the elongation accumulated in the test and Young's modulus of the material. Therefore, this study confirm a usefulness of compare experimental value with high cycle fatigue equation that shows relationship between the tensile test and the S-N curve of bolted joint in plastic region. As a result, plastic region tightening increase in 1.32 times of (Δl/l0)f value rather than bolted joint in elastic region tightening in tensile test.View full abstractDownload PDF (583K) -
Osamu YOKOTA, Yasunori SUGAWARA1996 Volume 34 Issue 4 Pages 256-262
Published: July 25, 1996
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSAn electromagnetic flaw detection method has been mainly applied to the measurement of crack size in the metal substrates and coating thickness on the composite materials. As for the measurement of a surface coating thickness, essentially there are three types of measurement which micrometer microscope, micrometer calliper and coating thickness meter can be required in JIS. The experiment was done to study of the accuracy of coating thickness measurement using coating thickness meter.
It is found experimentally that false coating thickness was generated by coating thickness meter for the measurement of ceramic coating thickness on stainless steel. But this study has not been any other reports yet. The main results are summarized as follows.
False thickness is influenced by blasting time, blasting distance and so on, But, it is not due to any surface roughnesses. It has been experimentally verified that false thickness is caused mainly by the presence of residual stress on which the surfaces of substrates were blasted with alumina grit materials.View full abstractDownload PDF (3985K) -
Yoshiyasu ITOH, Masataka TAMURA, Hideo KASHIWAYA, Yasuo TAKAHASHI1996 Volume 34 Issue 4 Pages 263-269
Published: July 25, 1996
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSA computer-aided interactive system for coating design has been developed, which enables to conveniently analyze the reaction diffusion of bonded materials including coating components and composites etc. This system consists of an interactive preprocessor, a reactive diffusion analysis based on a parabolic time law and a post-processor of calculated results. The analysis can be easily conducted by the selection of menues and the data input acceding to a few commands
The reaction diffusion of interface between the plasma sprayed CoCrAlY and the single crystal substrate of CMSX-2 are analyzed using the developed system. It is clear that the diffusion distance during heating process can not be ignored in comparison with the total diffusion distance. As a result, it is confirmed that the developed system is useful to apply for designing the coating system for gas turbine.View full abstractDownload PDF (4738K)
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