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62 巻, 4 号
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技術報告
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柳沢 平, ナーセル・バララーム1991 年 62 巻 4 号 p. 247-252
発行日: 1991/04/25
公開日: 2015/01/22
ジャーナル フリーAn equipment for in-stream treatment of ductile iron was developed to adopt for gravity die casting. The treatment unit which consists of pouring basin, reaction chamber and a reservoir for holding treated iron, has a frequent motion between melting furnace and permanent mold for consecutive pouring.
The effect of reaction chamber design and nodulizing alloy type on microstructure of cast specimens was studied using four types of reaction chamber design and five kinds of nodularizer at different preheating temperature of reaction chamber.
The results indicate that a carbide free structure with a high nodule count of up to 1500n/mm2 within the as cast structure of a permanent mold rod specimen of 30mm dia. can be achieved using this treatment equipment, by using suitable nodularizing alloy and process chamber design.抄録全体を表示PDF形式でダウンロード (3001K)
研究論文
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楊 栄顕, 片島 三朗, 田島 俊造, 辻 泰浩1990 年 62 巻 4 号 p. 253-258
発行日: 1990/04/25
公開日: 2011/07/27
ジャーナル フリーAbout the substitutional state between the EPS pattern-molten silumin on the new Evaporative Pattern Casting Process, the effects of the pouring system, vacuum degree, pouring temperature, whether coat is adopted or not on the substitutional state between the EPS pattern-molten silumin were investigated.
The obvious results are as follows :
(1) In the case under vacuum, the molten metal flows through the boundary of the EPS pattern and the mold firstly, then the unmelted and ungasified EPS pattern is wrapped in the molten metal and remains in that state for a little while.
(2) In the case without vacuum, the molten metal gets into the EPS pattern, then pushed-off the melted pattern which was heated by the molten metal, and filled up in a state of being nipped between the molten metal and the mold, to the boundary of the mold. The pattern that in a state of melted, after then gasified and discharged.
(3) There are no connections with the pouring system, pouring temperature, vacuum degree, whether coat is adopted or not. The molten metal expands with an isometric circular-arc shape nearly centering the gate.
(4) The flow velocity of the molten metal will increase, when the vacuum degree and pouring temperature were increased. Moreover, the flow velocity of the molten metal is in the order of the top, side and bottom pouring, both in the case of under vacuum and without vacuum.
(5) In the case of the coat adopted and without vacuum, the flow velocity of the molten metal becomes slower when compared with the case without coating, but is almost not affected by the kind of coat, the thickness of the coat and the kind of backing sand.抄録全体を表示PDF形式でダウンロード (799K) -
辻川 正人, 松本 宗久, 川本 信1990 年 62 巻 4 号 p. 259-263
発行日: 1990/04/25
公開日: 2011/07/27
ジャーナル フリーViscosity of Al-10%Cu-5%Mg alloy slurries containing alumina particles, were measured to clarify the possibility of die casting of these slurries. The basic rheological data were obtained by a double cylinder type high temperature viscosity meter at 650°C and 590°C. The date were compared with those of matrix alloy without particles. The shear rate used were from 50/s to 300/s. The result are as followings; (1) When the matrix was in liquid state (650°C), viscosities of the slurries were low and not affected by shear rate. (2) The viscosities of slurries containing about 50vol% primary crystals (590°C) without alumina particles was 3.5 Pa·s. The viscosity of the slurry containing 10%alumina particles increased twice. (3) A great thixotoropy was observed in partialy solidified slurries (590°C) both with and without alumina particles. The viscosity ratio of composite slurry at 300/s to that at 50/s was one-sixth. This difference was greater than that of slurry without particles. (4) When the shear rate was increased instanteneously, the viscosity drop of composite slurry was faster than that of slurry without particles. This can be explained by the concentration of alumina particles in the liquid phase and the fragmentation of primary crystal agglomerations by alumina particles. The date indicates that the composite slurries can be used for die castings.抄録全体を表示PDF形式でダウンロード (761K) -
滝田 光晴, 上田 俶完, 太田 晃三1990 年 62 巻 4 号 p. 264-269
発行日: 1990/04/25
公開日: 2011/07/27
ジャーナル フリーA special two-stepped austempering process of ductile iron was developed. In this process, the desired hardness is secured to improve wear resistance and strength in first step treated in the lower temperature bath(325-375°C) for short time (0-2min). In the second step in the higher temperature bath(440°C), the austenite transformed to perfect bainite and the retained austenite is reduced to improve the machinability in a short time (within 60min). The application of the iron austempered in this process to the sliding parts for automobiles confirmed the sufficient quality and machinability.
In this study, it is intented to make clear the mechanism of the bainite transformation and the improvement of hardness in this process. Ductile iron was two-stepped austempered at various temperature for various period. The microstructure was analized by the image analizing technique and the micro hardness testing.
Following results were obtained :
The harder acicular bainite precipitates from the neighborhood of graphite by the holding in the second step after holding in the first step. As holding in the second step, globular bainite which is less hard precipitates around the acicular bainite. However, the acicular bainite continues to grow maintaing high hardness during holding until finishing of treatment.
The lower the temperature of 1st-step holding and the longer the time of 1st-step, the volume fraction of the harder acicular bainite increases. The harder acicular bainite precipitated by holding at lower temperature even if a short time and grows during in second step contributes to the improve of hardness.
Whereas, the lower the holding temperature of 1st-step, the shorter the time of holding at higher temperature in second step to improve the machinability by reducing the retained austenite.抄録全体を表示PDF形式でダウンロード (814K) -
直井 孝夫, 渡辺 博美, 荒井 俊一郎, 南 和一郎, 千々岩 健児1990 年 62 巻 4 号 p. 270-276
発行日: 1990/04/25
公開日: 2011/07/27
ジャーナル フリーThe Behaviour of molten metal of cast iron poured into the full mold was investigated in various casting plans by using the apparatus for measurement of metal flow, and the case of cavity mold was also examined. The flow mechanism of the molten metal in the full mold was much different from that in the cavity mold due to the gas pressure of evaporated polystyrene. Generally the molten metal spread radially in front of the gate pushed forward by the succeeding molten metal filling the mold cavity. The flow velocity was slow and it flowed little turbulently compared with the case of cavity mold. The quantity of flow through the gate increased as the area between the molten metal and the polystyrene pattern increased. In the case of step gate using expanded polystyrene for runner and gates the molten metal generally flowed into the full mold through the top gate at first, and in the case of using cavity mold it flowed through the bottom gate at first.抄録全体を表示PDF形式でダウンロード (764K) -
金 基永, 鈴木 俊夫, 梅田 高照1990 年 62 巻 4 号 p. 277-282
発行日: 1990/04/25
公開日: 2011/07/27
ジャーナル フリーOne-piece and two-piece mold were used to investigate the effect of mold on the deformation of plane AC4C alloy castings. Both displacements of casting and mold were measured with three linear variable differential transformers.
Bending of mold when airgap forms is included in total deformation of two-piece mold, but is not in one-piece mold because mold doesn't bend when airgap forms.
There exists an inflection point on an measured airgap-time curve, and casting shows uniform thermal contraction after this point. It can be clarified by comparing the increase in airgap size after this point with the uniform thermal contraction estimated by corresponding temperature decrease. Therefore nonuniform deformation of casting finishes at this point. There is no significant difference in nouniform deformations for one-piece and two-piece mold castings after subtracting bending of mold for two-piece mold.
The cause of nonuniform deformation of casting after airgap forms may be due to temperature difference in solidified shell, which is discussed qualitatively by numerical calculation with elastic model using FEM.抄録全体を表示PDF形式でダウンロード (781K) -
加藤 鋭次, 上田 俶完, 松本 章宏1990 年 62 巻 4 号 p. 283-288
発行日: 1990/04/25
公開日: 2011/07/27
ジャーナル フリーThe fatigue and impact properties of Aluminum-Silicon casting alloys modified by various elements were investigated. The form of eutectic Si particle was different by each modification element. From the quantitative analysis, the round factor of the eutectic Si was about the same by each modification element with T6 treatment, but the particle sizes were different and was largest by Li treatment, followd by Sr treatment and smallest by Sb and Na treatment.
The fatigue and impact properties were influenced by the eutectic Si forms depending on different modification element. The eutectic Si particle forms of the alloy modified by Sb were more spherical and finally dispersed, that resistance against crack initiation and propagation was higher. The fatigue limits of alloys modified by Sb and Na were highest, while Sr and Li treatment were lower. However, alloy modified by Sr had shown highest fatigue strength at less than 5×106 cycles.
The alloy modified by Sb had shown lowest fatigue crack growth rate both for high and low ΔK values and had shown maximum stress intensity factor range at lower limit. The fatigue crack growth rate of Na modified alloy was lower in low ΔK range compared with Sr or Li modification, corresponding to this, range of lower limit of stress intensity factor was larger, however, it was lower at high ΔK range.抄録全体を表示PDF形式でダウンロード (990K) -
大原 伸昭, 加藤 榮一1990 年 62 巻 4 号 p. 289-295
発行日: 1990/04/25
公開日: 2011/07/27
ジャーナル フリーThe effects of Al, Ti, Bi, Te and S on the formation of hydrogen blowholes have been investigated by the technique of solidifying molten Fe-C-Si alloys in quartz tubes. This technique was employed to control the hydrogen content in the melts immediatately before solidifying and to eliminate the influence of mold conditions.
Results obtained are as follows ;
(1) The Al addition had no influence on the blowhole formation in white iron. On the other hand, the Al addition reduced the tendency of blowhole formation in gray iron.
(2) The addition of Ti had no influence on the blowhole formation in white iron.
(3) In the case of gray iron with Ti contents in the 0.091 to 0.108%, intermediate Al contents of 0.046% to 0.124% increased the tendency of blowhole formation and Al contents over 0.230% had no influence on the blowhole formation as compared with Ti-free samples.
(4) The addition of Bi, Te and S increased the tendency of blowhole formation in white iron.抄録全体を表示PDF形式でダウンロード (1294K)
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