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Volume 27, Issue 6
Displaying 1-6 of 6 articles from this issue
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Yoshio Fujiwara, Humihiro Ueda, Hiroaki Masatomi, Hisashi Suzuki1980 Volume 27 Issue 6 Pages 181-184
Published: August 25, 1980
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSFatigue fracture properties of hot isostatic pressed WC-12%Cc alloys having coarse and fine WC particles were investigated and macro-and microfractografic analyses were carried out. The results obtained are as follows: (1) Fatigue strength increases with increase of WC particle size. (2) Fatigue strength of hot isostatic pressed alloy becomes larger than those of conventionally sintered alloy. (3) Fractographic analysis reveals the existence of characteristic fracture surface of fatigue. A some region of fatigue fracture surface looks weakly bright. In this region, saw tooth type crack can be observed. These pattern consist from the Co (h.c.p.) phase.View full abstractDownload PDF (6357K) -
Hisashi Suzuki, Koji Hayashi, Yasuro Taniguchi1980 Volume 27 Issue 6 Pages 185-189
Published: August 25, 1980
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSEffects of replacement of tungsten carbide with molybdenum carbide on the properties of WC-Co alloys were studied. Two sorts of alloy systems, i.e., a WC-Mo2C-Co alloy system prepared by using individual powder as a starting material, and a (W, Mo)C-Co alloy system by using cobalt and (W, Mo)C solid-solution powders were used as specimens.
The room temperature T. R. S. Of WC-Mo2C-Co alloy system dropped sharply with increasing amount of molybdenum carbide. On the other hand, that of (W, Mo)C-Co alloy system was hardly affected by the amount of molybdenum carbide. However, the hardness of (W, Mo)C-Co alloy was not improved, and the two-phase region became narrower with increasing the amount of molybdenum carbide.View full abstractDownload PDF (2328K) -
Kiyoaki Akechi, Zenshiro Hara, Kenzo Hanawa1980 Volume 27 Issue 6 Pages 190-196
Published: August 25, 1980
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSTwo types of commercial Ti alloy powders (Ti-6AI-4V and Ti-6A1-2Sn-4Zr-6Mo, <500 μmφ) made by a rotating electrode process (REP) have been resistance-sintered in air. The relation between physical and mechanical properties of sintered specimens and their resistance-sintering conditions have been studied. The effects of various heat treatments on the properties of resistance-sintered specimens have been also examined.
These powders in a die insulated by mica were resistance-sintered under a pressure (1.2 t/cm2). The condition of resistance-sintering was as follows: electric current; 7.6-15 kA, voltage; 2.5-4.7 V, time; 0.6-2.0 sec (30-100 C, C; cycles) and power input; 45-190 kVAC/g (1 kVAC=9.8 J).
By the resistance-sintering with a power input higher than 140 kVAC/g, specimens having high density-ratio (>98% theoretical) and high tensile strength could be obtained (Ti-6A1-4C; 120 kg/mm2, Ti-6A1-2Sn-4Zr-6Mo; 100 kg/mm2). Resistance-sintered specimens of both alloys were strengthened by the solu-tion-treatment and the aging (STA) heat treatment (tensile strength-130 kg/mm2). Tensile strength of resistance-sintered Ti alloys was almost comparable to that of those water-quenched.View full abstractDownload PDF (6482K) -
Masaharu Miyano, Hiroshi Inoue, Jiro Shibata1980 Volume 27 Issue 6 Pages 197-200
Published: August 25, 1980
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThis investigation was carried out to examine the influence of heating condition, pretreatment and com-position of material on the incubation period appearing in induction heating of Fe-Graphite compact.
The results were summarized as follows:
1) The incubation period increases with decreasing frequency of induced current and density of the compact. It also increases with increasing graphite content.
2) The addition of copper and preheating-cooling of the compact before induction heating reduce the incubation period.
3) The induction heating up to 900°C reduces extremely the incubation period in re-heating of the compact after cooling.
4) The possible explanation for the existence of the incubation period is that the compact may be not heated effectively since the high frequency current will penetrate deeply into the compact, because of its high electric resistance.
However, when the electric resistance is decreased by the evolution of absorbed gases and also by the neck-growth in the compact, an effective rapid heating becomes possible.View full abstractDownload PDF (1774K) -
Katsuhiro Nishiyama, Hirohisa Suwabe, Noboru Ichiyama1980 Volume 27 Issue 6 Pages 201-206
Published: August 25, 1980
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSAn investigation was made on the damping properties of sintered SUS304L stainless steels modified by the corrosion treatment. The results were summarized as follows:
(1) The damping capacity of sintered SUS304L stainless steels modified by the intergranular corrosion treatment was approximately two to forty times as large as the value of as-sintered compacts.
(2) The increases of (St-Ss) in the sintered compact using -100 mesh powders were higher than that of -20/+60 mesh powders, where St and Ss are the damping capacities of specimen with and without intergranular corrosion treatments respectively.
(3) The increases of (St-Ss) on the corrosion time using the corrosion reagent of 10%CuSO4-H2SO4 were higher than by using of 65%HNO3.View full abstractDownload PDF (4426K) -
Hideo Kayano, Ryoko Takagi1980 Volume 27 Issue 6 Pages 207-211
Published: August 25, 1980
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSIn the present study particle powders of copper coated with thin films of organometallic complexes were pressed and then heat treated. The complex compounds were thermally decomposed to carbide particles of uniform dimension or to fine oxide particles; these particles were homogeneously dispersed in the alloys, thus permitting the production of the conductive materials having fairly low or negative temperature gradient of resistance to keep high conductivity at higher temperature. It may be said that this type of new conductive materials overthrows the Matthissen's rule. Thus deviation from the Matthissen's rule is particularly re-markable in the samples added with Ni(AA)2, Ti(AA)3, 1Mn4Ni(AA)2 and SmCo5(AA)2. This deviation may be attributed to s-d interaction of the dispersed amorphous transition metal compounds and matrix copper atoms.View full abstractDownload PDF (1730K)
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