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49 巻, 9 号
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研究論文
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西川 進, 山本 悟, 川野 豊1977 年 49 巻 9 号 p. 525-532
発行日: 1977/09/25
公開日: 2012/07/10
ジャーナル フリーTests were made to examine the required conditions and hypothetical mechanism of eutectic formation which had been proposed by other investigators, on commercial and highly pure synthetic irons and a new mechanism of formation was proposed. It was found that conditions, such as hypoeutetic composition of alloys, high cooling rate, titanium-treatment and melting and freezing in vacuum, are not necessary nor sufficient for eutectic graphite formation, and that various hypothetical mechanisms of formation can not explain the experimental results satisfactorily. Therefore, a new mechanism is proposed : eutectic graphite may be formed as a result of the γ-phase strongly obstructing the graphite growth during solidification which makes graphite fine and multiplys branch.抄録全体を表示PDF形式でダウンロード (999K) -
鷹取 正六, 桜井 市蔵1977 年 49 巻 9 号 p. 533-538
発行日: 1977/09/25
公開日: 2012/07/10
ジャーナル フリーA study was made on the relation between different casting conditions and the tendency to pit hole (which resemble superficial blow holes and sometimes pit deeply under the surface of the casting) on low carbon steel pipes of 10mm wall thickness cast centrifugally in water shower cooled metal mold. The thicker the refractory coating on the inner surface of the mold or the lower the spinning speed or the lower the thermal conductivity of the coating or the more the amount of bentonite in the coating is, the more the pit holes are apt to occur. The source of pit holes is the gasified combined water which is released gradually from the bentonite in the coating during the period when small liquid canals are formed among cellular dendrites in the outer layer of pipes. If the gas pressure becomes higher than the outward pressure of the liquid among cellular dendrites in centrifugation, gas pushes the liquid inward and depending on the balance between the rate of increase of gas pressure and solidification rate of the outer layer of the pipe, gas can not reach the inner perfect molten zone, which lead to the formation of pit holes.抄録全体を表示PDF形式でダウンロード (789K) -
尹 義博, 西 成基, 篠田 武雄1977 年 49 巻 9 号 p. 539-544
発行日: 1977/09/25
公開日: 2012/07/10
ジャーナル フリーPrimary and secondary dendrite arm spacing increases with decreasing average cooling velocity. But primary arm spacing increases with Cu content, while secondary arm spacing does not change appreciably with Cu content over the composition range investigated. The relationships between these were obtained as follows;
λ1=0.87√Co/Va, λ2=177Va−1/3
where, λ1 is the primary arm spacing (mm), Co is the Cu content (%), Va the average cooling velocity (°C/min) and λ2 the secondary arm spacing (μ). As the solidification rate increases, the size and mean free path of the θ phase show an appreciable decrease. And the mean free path between θ-particles is similar to the order of the secondary dendrite arm spacing. With decreasing distance from the chill face (that is, increasing solidification rate), the amount of θ phase decreases over the range of solidification conditions investigated in this paper. As distance from chill becomes smaller, lattice constant decreases, and the Cu-content in α-matrix increased. From these results, the behavior of second phase in unidirectionally solidified Al-Cu alloys could be confirmed quantitatively.抄録全体を表示PDF形式でダウンロード (688K) -
松原 安宏, 大城 桂作, 松田 公扶1977 年 49 巻 9 号 p. 545-550
発行日: 1977/09/25
公開日: 2012/07/10
ジャーナル フリーTwo series of cast irons containing 15%Cr and 30%Cr were melted at 1,400°C and quenched by water spray while freezing unidirectionally, and the mechanism of growth of eutectic cells was investigated from the shape and structure of the eutectic cell. Because the shape of the eutectic cell interface is affected strongly by the depth of the solid-liquid region, the eutectic freezing ranges of eutectic cast irons containing about 10 to 50%Cr were measured by thermal analysis.
The eutectic freezing range (ΔTE) varied with chromium content and was maximum (65°C) at 15%Cr and minimum (21°C) at 30%Cr. Hence the length of the eutectic freezing zone, when irons solidified unidirectionally under the same thermal gradient, was largest in 15%Cr irons., and smallest in 30%Cr irons. Eutectic colony size (Ew) appeared to be proportional to 0.45 power of the eutectic freezing time (Δt) because of the fact that Ew was proportional to ΔTE0.45 and that Δt was in proportion to ΔTE. The transverse section of a eutectic cell had a nearly round shape and the rate of the radial growth of the eutectic cell (Rr) decreased gradually toward the cell boundary. Rr at the same eutectic freezing ratio was considerably smaller in 15%Cr irons than in 30% Cr irons. Since the coarseness of the eutectic structure was subject to the rate of vertical growth to a eutectic cell interface, the eutectic carbides existing in the colony became larger near the colony boundary and this tendency was much greater in 15% Cr irons.抄録全体を表示PDF形式でダウンロード (861K) -
玉崎 洋一1977 年 49 巻 9 号 p. 551-556
発行日: 1977/09/25
公開日: 2012/07/10
ジャーナル フリーIn Cu-5 and 10%Sn alloys, mold reaction between melt and plaster mold was prevented by adding 0.5% of Be or 1.0% of Al which improved the casting surface roughness to 10 to 20 microns maximum when melt was poured at as high as 1,250°C. In Cu-20 and 40%Zn alloys, mold reaction was prevented by adding 0.5% to 1.0% of Al or 0.5% of Si and the casting surface roughness was improved to 13 to 17 microns when the melt was poured at as high as 1,200°C for 20%Zn and 1,170°C for 40%Zn alloy. In Cu-5%Pb alloy, mold reaction was somewhat prevented by the addition of 2% of Be or Al which improved the casting surface roughness to 25 to 35 microns maximum when melt was poured at as high as 1,250°C. But for Cu-10%Pb alloy, mold reaction was insufficiently prevented by the addition of 2% of Be or 3% of Al which only improved the casting surface roughness to 40 to 65 microns maximum. Thus it was considered that Cu-10%Pb alloy could not be applied to precision casting in plaster molds. In Cu-10%Sn-2%Zn bronze, the casting surface roughness was improved by the addition of 0.5% of Be or Al to 20 microns maximum when melt was poured at as high as 1,250°C, but in Cu-5%Sn-5%Zn-5%Pb bronze, casting surface roughness was just a little but improved by the addition of 0.5% of Be or 1.0% of Al, that is, to 30 microns maximum when melt was poured at as high as 1,200°C.
It was confirmed from these investigations that Be, Al and Si were important and effective additional elements to prevent mold reaction and obtain smoother casting surface because they form stable selective oxidation film around the copper-base alloy poured into plaster molds.抄録全体を表示PDF形式でダウンロード (2993K) -
竹内 宏昌, 永瀬 国士, 梅田 高照, 木村 康夫1977 年 49 巻 9 号 p. 557-562
発行日: 1977/09/25
公開日: 2012/07/10
ジャーナル フリーSolidification process was examined experimentally and numerically. It was found that the solidification time at the plate of L-shaped castings is determined in accordance with Chvorinov's rule, but the solidification constant varies with the mold thickness. Solidification time at the junction can be predicted by increasing the modulus 1.1 times as large as that of the plate. The progress and time of solidification can be predicted quantitatively by numerical calculation. Solidification time is dependent upon the heat transfer coefficient between mold and castings, but is independent of that between mold and air. The value of the heat transfer coefficient between mold and castings was evaluated as 0.02cal/cm2⋅sec⋅°C. Mold dressings can change the solidification progress and time at the junction.抄録全体を表示PDF形式でダウンロード (685K)
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