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Volume 21, Issue 2
Displaying 1-5 of 5 articles from this issue
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Isao Konda, Kumao Okita1974 Volume 21 Issue 2 Pages 38-42
Published: May 25, 1974
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe sintered iron compacts generally have many pores. The author investigated how the amount and shape of pores affect the fatigue fracture of sintered iron compacts and observed microscopically the aspects of its fatigue fracture under low cycle.
The following conclusions are obtained from the above microscopical observations.
1) Firstly slip bands generate in grains and they grow into fatigue crack, and the crack appeared to propagate from pore to pore through in grain or along grain boundary.
2) Fatigue cracks generate from all pores. But, fatigue crack grows generally from medium or fine pores and scarcely from larger pores.View full abstractDownload PDF (6277K) -
Hidenori Kuroki, Tsuneyuki Ide, Youichi Tokunaga1974 Volume 21 Issue 2 Pages 43-50
Published: May 25, 1974
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIt is the purpose of this study to investigate the effects of shape of pores on toughness and ductility of sintered iron.
Compacts with a density range of 5.9-7.6 g/cm3 were pressed from electrolytic iron powder and pre-sintered at 1100°C for 10 min in hydrogen. Subsequently they were infiltrated with ferrous chloride by soaking for 4 min in its melt at 750°C.
Activated-sintering (or reduction of ferrous chloride) was carried out at 800°C, 950°C and 1100°C for 5 min-3 hr in hydrogen. Impact and tensile properties of these materials with round pores were compared to those of conventionally sintered ones with sharp edged pores.
The results were summarized as follows.
1. The roundness of the pores caused an increase in the charpy shelf energy and made the ductile-brittle transition more evident.
For this reason, the impact strength of the activation-sintered iron was, at 200°C, about two times as large as that of conventionally sintered iron with the same density, but at low temperatures, smaller than that.
2. Activated-sintering increased the ultimate tensile strength and the fracture strain by 10-50% over conventional sintering. But the yield strength was hardly affected by the pore shape.
3. The relative strength and the fracture strain of porous materials were expressed as functions relating not only to the porosity but also to the notch effect of the pores.View full abstractDownload PDF (3087K) -
Hisashi Suzuki, Kozi Hayashi, Osamu Terada, Masahide Fukuda1974 Volume 21 Issue 2 Pages 51-55
Published: May 25, 1974
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe various properties of this sort of composite alloys would be affected by the grain size of binder phase, as well as by the other factors. Therefore in this paper, the factors affecting the grain size of TiC-(10-30)%Mo-(10-30)%Ni alloys were mainly studied.
Results obtained were as follows: (1) The grain size was generally revealed out by thermal etching. (2) The grain size increased with sintering temperatures, C and Ni contents, and with decreasing Mo contents. The large grain size like a columnar structure was characterized. Discussions about these results were given. (3) The effect of grain size on the strength of alioys and also the structure of the grain boundary were investigated.View full abstractDownload PDF (7047K) -
Susumu Tamagusuku, Yoshinobu Oda1974 Volume 21 Issue 2 Pages 56-59
Published: May 25, 1974
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe ferromagnetic powders dispersed in coating surfaces of commercial broadcast video tapes were exa-mined using X-ray diffraction and Mossbauer technique. X-ray diffraction of the coatings showed the presence of preferred orientation having [110] parallel to an alignment direction on the plane of the tape surface. For the majority of particles examined the easy direction was also parallel to the above direction. These results are compared with those obtained by electrical conductivity measurements.View full abstractDownload PDF (1479K) -
Ryozo Hayami, Mikio Iwasa, Makoto Kinoshita1974 Volume 21 Issue 2 Pages 60-63
Published: May 25, 1974
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDensification behavior of the compact during hot-pressing can be represented by equations of the type f(p)=kt+C, where p is the relative density at the time t.
These equations can be expressed in the form ??, where f(ρ) is the time after ρ reaches p and ?? is the time for the densification from ρ=p to q. Calculable constants a and b depend on the form of f(ρ).
Numerical tables are given of f(ρ) in relation to ρ, and to ??, for four equations corresponding to densifications, which are used by the plastic flow controlled and the diffusion controlled mechanisms.
The application of the tables and figures to the analysis of experimental data is described.View full abstractDownload PDF (231K)
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