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33 巻, 6 号
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研究論文
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植田 昭二, 坂口 弘志1961 年 33 巻 6 号 p. 397-404
発行日: 1961/06/25
公開日: 2012/10/29
ジャーナル フリーFluid flow in the gating system for marine propeller casting has been studied with the aid of transparent models made of plastic, in which the flow of metal is simulated by that of water. It has been also attempted to add the small particles of solid substances such as wax or porous rubber, whose density was 0.87∼0.02, to simulate the presence of dross. It has been pointed out that:
1) Tapered sprues were unlikely to cause gas aspiration compared with parallel sprue. The dimensions of height and diameter of sprue should be designed as small as possible to minimize the momentum of fluid which is given in sprue.
2) L-bend type spruee base caused severe agitation and air entrapment. Surge sump type sprue base was considerably superior to L-bend base, and splashing and agitation was much less. In this base trapped air was also washed away more quickly.
3) The use of 2nd sprue was effective to absorb the momentum fo the flow without agitation, and also to eliminate the dross and trapped air.
4) Inversely tapered runner caused air entrainment. The runner should be designed to minimize the air trap by making the height of channel small relative to its breadth.
5) In comparison with the skirt type ingate, the agitation and the rotation of fluid flow in the propeller cavity was reduced by using the multiple hole ingate. However, the behaviour of the flow when it entered to the propeller cavity through ingate was much influenced by the momentum of the flow.抄録全体を表示PDF形式でダウンロード (1045K) -
音谷 登平, 徳永 洋一1961 年 33 巻 6 号 p. 404-411
発行日: 1961/06/25
公開日: 2012/10/29
ジャーナル フリーAfter austenizing at 900°C for 30 minutes, the S-curve for 0.4%Mo-1.3%Cu cast iron was determined by metallographic and dilatometric methods. From this result, the effects of isothermal treatments ranging from 250 to 675°C on its various mechanical properties were investigated, and summarized as follows :
1) During the isothermal holding of the cast iron after ending times of S-curve, there appeared general decrease in hardness, which may be explained by assuming that undecomposed austenite was stabilizing in matrix structure.
2) The tensile strength and toughness were progressively increased by isothermal treating at lower bainite range, and dropped as the treating temperature was raised to upper bainite range due to the restraining of the transformation. The lower pearlitic treatments provided higher tensile strength, with lower toughness.
3) Rolling abraision test (dry and with sliding of 10%) showed that (i) the wear loss of the heat-treated iron was decreased in case of combination with flake graphite cast iron and increased with high carbon tool steel, (ii) most improvement of Mo-Cu cast iron in wear resistance was gained by marquenching and isothermal treatment at 375-425°C, (iii) in lower bainitic treating at 325°C, on the other hand, the wear resistivity was decreased relatively, and (iv) no isothermal pearlitic iron proved wear resistivity in this works.抄録全体を表示PDF形式でダウンロード (991K) -
丸山 益輝1961 年 33 巻 6 号 p. 412-420
発行日: 1961/06/25
公開日: 2012/10/29
ジャーナル フリーThe effects of the inoculation of ferro-silicon on the graphite form of vacuum-molten iron were researched. The rusults obtained are as follows.
1) When the grains of ferro-silicon were added on the vacuum-molten iron, the innumerable graphite nuclei, from which the spheroidal graphite grew, deposited in the high silicon parts segregated in the molten iron.
2) Spherpidal graphites were counted up in the molten iron when ferro-silicon was added.
3) Graphites crystalizing during solidification showed a tendency to take a flake form or a fine eutectic form, except the ones depositing on the existing spheroidal graphite nuclei.
4) The larger the grain size of ferro-silicon was, the more the silicon segregated in the molten, and the tendency to deposit a spheroidal graphite nucleus was increased.
5) With the increase of addition amount of ferro-silicon and the lowering of addition temperature, the segregation of silicon in molten iron increased and it contributed to deposit a spheroidal graphite nucleus.
Considerating the results of various experiments obtained above, the fundamental conditions of generation of spheroidal graphite were summarized as follows :
1) The oxygen content and sulphur content of molten iron should be kept under a limitted value.
2) The graphite should be precipitated directly from the molten iron in a short time.
From the above consideration, it was deduced that the graphite form (whether the graphite grew in the spheroidal form or the flake form) depended up on the change of surface tension between molten iron and graphite.抄録全体を表示PDF形式でダウンロード (992K) -
阿部 善彦1961 年 33 巻 6 号 p. 421-427
発行日: 1961/06/25
公開日: 2012/10/29
ジャーナル フリーOn dry abrasion, the wear resisting properties of the spheroidal graphite cast steel of various matrices have been studied which were obtained by different heat-treatments such as normalizing, oil quenching and tempering. The upper specimens have various heat treated matrices and the lower specimen has the normalizing structure. The results obtained can be summarized as follow:
1. Surface hardness after abrasion showed the difference by the matrices, but it had a tendency to attain constant value along with the increase of running distance.
2. Although the surface of specimens was adjusted constant by mechanical finishing before wearing test, surface roughness approached to the characteristic curves in each combinations of matrices between upper and lower specimens.
3. The lustrous degenerative layer as seen on samples tempered at low temperature was produced by physical factors such as work hardening and tempering effects.
4. On the contrary, the grayish layer as seen on samples tempered at high temperature was very thin and produced by chemical factors such as oxidizing or nitriding.
5. The upper specimens having much grayish area did not so much wear the lower specimens, but they showed themselves less wear resisting. On the contrary, the specimens which were covered with lustrous degenerative layer, showed more wear resisting, but the wearing amounts of the lower specimens were increased. Therefore, the combination of the extremely different matrics and the identical matrices must be avoided.抄録全体を表示PDF形式でダウンロード (859K)
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