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45 巻, 7 号
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研究論文
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宮田 征一郎, 菊地 政郎1973 年 45 巻 7 号 p. 563-572
発行日: 1973/07/25
公開日: 2012/09/21
ジャーナル フリーIt is considered that there is a close relationship between mechanical properties and graphite structure of cast iron. It is essential to quantitatively express the graphite structures to discuss the mechanical properties quantitatively. The purpose of this study is to quantitatively express the graphite structures using statistical methods. The results obtained are summarized as follws :
(1) Mean length and width of graphite particles were numerically estimated.
(2) Proportion of graphite area was numerically estimated.
(3) Each shape of flake, granular and spherical graphites was numerically expressed.
(4) The irregularity of distribution of graphite particles was numerically expressed.抄録全体を表示PDF形式でダウンロード (903K) -
津田 昌利, 江川 勝一1973 年 45 巻 7 号 p. 573-581
発行日: 1973/07/25
公開日: 2012/09/21
ジャーナル フリーThe purpose of this investigation is to examine the influences of cooling rate and additional elements, Mg, Ca and Na on the shape and size of primary silicon in Al-20%Si alloys.
(1) In the specimens quenched into ice water at the temperature in the liquid state fine particles of silicon crystallized, but dendritic silicons crystallized in the alloy treated with phosphorus.
(2) Plate-like silicons were observed in the specimen quenched into ice water at the temperature below 650°C which grew in size until eutectic temperature was reached.
(3) The size and shape of primary silicon became coarse changing to plate form from fine particles with decrease of cooling rate.
(4) Since phosphorus concentrates at places of high calcium even a small quantity of calcium leads to coarsening of primary silicon.
(5) Magnesium or calcium addition promoted the growth of plate-like silicon with feathery silicon at the tip.
(6) Spheroidizing of primary silicon was attained by the gradual deposition of silicon through the liquid around primary silicon with poor silicon content and high viscosity due to sodium addition.
(7) Even if about 0.5% of sodium is added to make primary silicon spheroidal, dendritic primary silicon will crystallize under rapid cooling, and conversely, spheroidal form of silicon is difficult to retain under exremely slow cooling.抄録全体を表示PDF形式でダウンロード (1643K) -
三宅 一生, 喜多 清, 西山 幸夫1973 年 45 巻 7 号 p. 582-591
発行日: 1973/07/25
公開日: 2012/09/21
ジャーナル フリーIn previous works, tension test results of test pieces which were taken from different parts of the body and Y-block of steel castings were discussed and it was clarified that elongation of as-cast iron is lower than that of the annealed one and that elongation value on a piece taken from the center in Y-block is lower than that taken from the bottom part. The purpose of this study is to the relation between each of these results and the feature of the fracture of the tension pieces. As for clarify the method, the authors have examined the results of electron microscope scanning on the fracture of SC 46 to 49 tension pieces and Cu-Sn-Zn alloy. The results are as follows;
(1) The feature on fracture is different between the center and the outside of tension pieces and the smaller the difference is, the larger the elongation. Especially, when the features are finer at the outside parts and when the dimple pattern is deeper, the elongation is larger.
(2) The fact that elongation of the as-cast iron is smaller than that of the annealed one is due to quasi-cleavage which occurs at the center of fracture.
(3) The fact that elongation value on a piece taken from the center in Y-block is lower than that on the bottom part, is attributed to microvoids or inclusions which increase at the center due to the difference in freezing process. It is believed that these defects are the beginnings of the dimple pattern and that the dimple pattern is made shallow and large because of them.抄録全体を表示PDF形式でダウンロード (1846K) -
岡田 千里, 中江 秀雄, 祖父江 昌久, 横井 和明1973 年 45 巻 7 号 p. 592-597
発行日: 1973/07/25
公開日: 2012/09/21
ジャーナル フリーAn investigation has been made on the influence of melting conditions on the properties of iron melted in coreless induction furnace. Important properties of iron such as tensile strength, hardness, bending strength and chilling tendency were determined as a function of holding time, melt temperature, types of furnace lining and innoculation. The following results were obtained.
(1) Mechanical properties of iron are very much dependent on the melting conditions, particularly on the holding time. It has been shown that the strength of iron is greatest at the beginning of holding.
(2) The chilling tendency becomes more apparent by holding at a higher temperature, using rusty raw materials and by the dissolution of the neutral lining.
(3) These results are correlated to the change in nitrogen content and the number of eutectic cells of iron. Therefore, it might be concluded that these two are the most important factors influencing the properties of iron.抄録全体を表示PDF形式でダウンロード (671K) -
松藤 恭介, 久保 真一1973 年 45 巻 7 号 p. 598-605
発行日: 1973/07/25
公開日: 2012/09/21
ジャーナル フリーLow frequency induction furnaces have been rapidly developed in use in the last few years, and various researches have been made on the operation of the furnaces. It is generally understood that the iron melted by induction furnace has a strong chilling tendency and is prone to form shrinkage defects.
When melting by the low frequency induction furnace, continuous batch melting is the common practice, a part of molten iron being tapped and replaced with a cold charge of steel scrap and returns. In our operation, with four 8-ton induction furnaces, 4.4 tons of molten iron is usually tapped and a same amount of cold rolled steel scrap and returns is recharged.
The present experiment was conducted to examine the influence of the proportions of steel scrap in the charge, ranging from 10 to 90 percent, on some properties of induction melted iron. The results obtained were as follows :
(1) No change in chilll depth was observed in chill tests with varying the proportion of steel scrap in the charge.
(2) The degree of normality and quality factor slightly decreased by increasing the proportion of steel scrap in the charge, while the relative hardness did not show any appreciable change. Therefore, if the carbon equivalent is kept constant, the amount of steel scrap charged may be varied depending on the quantities of returns available.
(3) Hydrogen and oxygen contents in the iron slightly increased by increasing the proportion of steel scrap in the charge, while hydrochloric acid-soluble nitrogen content decreased.
(4) Inoculation had no significant influence on the gas content in the molten iron.抄録全体を表示PDF形式でダウンロード (803K)
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