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52 巻, 11 号
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研究論文
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堤 信久, 出津 新也1980 年 52 巻 11 号 p. 623-628
発行日: 1980/11/25
公開日: 2012/03/28
ジャーナル フリーThe present investigation has been carried out in order to obtain more information on the behavior of nitrogen in the gray cast iron by analyzing the hydrochloric acid-soluble nitrogen (NS) and acid-insoluble nitrogen (NI) determined by means of JIS G1228 method. Nitrogen in gray cast iron combines with the titanium existing in or added to the molten iron and forms TiN, which tends to float to the upper part of the specimen bar due to the difference in the density of TiN and the molten iron. When the mold temperature is high, the floating of TiN is pronounced, because the solidification time is longer. When nitrogen content is increased, with titanium content held constant, a large amount of TiN is formed and floats in a pronounced way.抄録全体を表示PDF形式でダウンロード (694K) -
大城 桂作, 白木 茂敏, 松田 公扶1980 年 52 巻 11 号 p. 629-634
発行日: 1980/11/25
公開日: 2012/03/28
ジャーナル フリーHypo-eutectic irons with 5%, 10%, 15% and 30% chromium and with 0.5 to 3.8% carbon were quenched during solidification, and the dendrite arm spacings were measured to clarify the growth process of the primary dendrite in Fe-Cr-C alloys. The distribution of chromium in the dendrites was analyzed with an electron probe micro-analyzer to investigate the solute redistribution during dendrite growth. The secondary arm spacing (D2) during solidification was expressed by the empirical equation as follows: D2=A2θf0.30, where θf was the solidification time. A2 decreased with increasing chromium content, carbon content and cooling rate. The equation Ḋ2/D2=0.30 θf−1 indicates that coarsening and coalescence of the secondary arms occur more frequently in the earlier stages of solidification than in the later stages. The distribution coefficient (KCr) of chromium in the primary dendrite decreased almost linearly with increasing carbon content. In the specimens with chromium ranging from 5 to 15%, KCr was little affected by the chromium content and was expressed by the next equation.
KCr=−0.11(%C)+0.99
KCr of the 30% Cr iron was appreciably larger than that given by the above equation. The segregation ratio of chromium in the dendrite is quantitatively expressed by the ratio of the chromium content in the boundary of the dendrite (C??) to that in the core (C??). The ratio C??/C?? decreased gradually from 1.8 and 1.5 to 1.0 with increasing carbon content in the 5% and 10% chromium irons. On the other hand, C??/C?? of the 15% chromium irons was at the maximum value 1.4 at about 1.1% carbon. C??/C?? of the 30% chromium irons was less than 1.1. The results could be explained by the dependence of C??/C?? on both KCr and the fraction of the primary solid.抄録全体を表示PDF形式でダウンロード (666K) -
新山 英輔, 内田 敏夫, 森川 穰, 斉藤 茂樹1980 年 52 巻 11 号 p. 635-640
発行日: 1980/11/25
公開日: 2012/03/28
ジャーナル フリーVarious methods of predicting shrinkage in castings from the results of numerical calculation of the temperature field during solidification have so far been proposed. The means of increasing the usefulness of such prediction were studied. (1) In numerically treating a casting on a 2-dimensional section some errors can be induced by neglecting the heat flow in the direction perpendicular to the plane of the section. A method of approximation was proposed where the value of the latent heat of freezing of the cast metal is changed in such a way as to give a roughly correct solidification time even when the perpendicular heat flow is neglected in the calculation on the 2-dimensional section. The usefulness of the method was demonstrated with some examples. (2) It was shown that mapping of calculated temperature gradient at the time of solidification can be a powerful tool in predicting shrinkage cavities, particularly those occuring along the centerline of the castings. In the actual castings, shrinkage cavities were found in those areas where the temperature gradient at the time of solidification was calculated to be below 2 or 3 degrees per centimeter. Cavities were not found in castings whose design was changed to eliminate the areas of low temperature gradient.抄録全体を表示PDF形式でダウンロード (594K) -
千々岩 健児, 白髭 勝男1980 年 52 巻 11 号 p. 641-647
発行日: 1980/11/25
公開日: 2012/03/28
ジャーナル フリーThe changes of the pressure of the molten metal in the mold cavity of aluminum die castings and their effects on the strength of the products were investigated. A cold-chamber-type die casting machine with pressing capacity of 80 tons was used, and aluminum was poured into a metallic mold with a curved groove cavity. The pressure of the molten metal was measured by using a special high pressure-high temperature pressure gauge developed by the authors. The experiments revealed the following results. (1) The pressure in the mold cavity gradually rises as it gets farther from the gate. (2) The pressure at each point in the cavity rises up to a peak pressure and then falls. (3) The peak pressure is higher near the gate than at a farther point in the cavity. (4) Water hammering phenomenon is sometimes observed. (5) The pressure is influenced by the mold temperature and the pouring speed. (6) The strength of the products is influenced by the peak pressure. The higher the peak pressure is, the higher the tensile strength is. These results have disclosed how the pressure of the molten metal changes in the mold cavity which has been unknown so far. Significant suggestions to the die-casting technique have been obtained through the study.抄録全体を表示PDF形式でダウンロード (667K) -
岩堀 弘昭, 米倉 浩司, 山本 善章, 中村 元志1980 年 52 巻 11 号 p. 648-652
発行日: 1980/11/25
公開日: 2012/03/28
ジャーナル フリーThe cause of gas defects often occurring at the molten cast iron-steel insert interface was investigated. When such melts as cast iron and Fe-3%C, Ni-2%C, Fe-2%Si and Al-20%Si alloys are cast, no gas defect occurs on the steel surface free from iron oxide. When the steel surface is contaminated with iron oxide and the molten metal contains a certain amount of carbon, gas defects emerge. The gas defects increase with increasing iron oxide on the steel surface. The evolved gas contains a high concentration of CO2. The gas defects are resulted from the reaction of iron oxide and carbon contained in the molten metal at the cast iron-steel interface.抄録全体を表示PDF形式でダウンロード (651K)
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