巻号一覧
後続誌
59 巻, 2 号
選択された号の論文の7件中1～7を表示しています
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技術報告
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片岡 義博, 伊藤 鉄美, 樋口 正司, 村井 香一1987 年 59 巻 2 号 p. 74-78
発行日: 1987/02/25
公開日: 2015/01/27
ジャーナル フリーIt has been known that a small addition of tin stabilizes pearlitic structure but an excessive addition degenerates spheroidal graphites. The critical amount is not the same but may vary depending on raw materials, melting conditions and cooling rate after casting. Molten iron with relatively high purity was prepared in a high frequency induction furnace, using steel scrap as raw material and electrode graphite as carburizer. Effects of the amount of tin addition and casting section thickness on structure and mechanical properties were investigated with the following results :
(1) About 0.1% of tin results in complete pearlitic matrix structure and the highest mechanical properties. (2) Increased tin addition does not deteriorate spheroidal graphite up to 1.0%Sn. But mechanical properties, particularly ductility, are lowered rapidly with tin upto 0.3%, while little change is observed with further tin addition.抄録全体を表示PDF形式でダウンロード (2591K)
研究論文
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井ノ山 直哉, 結城 勇, 山本 悟, 川野 豊1987 年 59 巻 2 号 p. 79-84
発行日: 1987/02/25
公開日: 2011/09/23
ジャーナル フリーA kinetic study of the first stage graphitization in white cast irons containing chromium has been carried out based upon quantitative structural analysis. The results are as follows : (1) The dissolution of cementite is the main reaction in the first stage graphitization. (2) Additional element chromium retards the reaction of cementite dissolution with increasing chromium content in the specimens and prolongs annealing time. (3) The rate constant Kd of cementite dissolution decreases exponentially with the chromium concentration on the surface of dissolving cementite during graphitization. (4) The above results are explained in terms of the structure and bonds of cementite crystal. Namely a chromium atom forms a stronger bond than an iron atom and hence, when present in cementite, it makes cementite more stable.抄録全体を表示PDF形式でダウンロード (706K) -
山田 人久, 桜井 隆, 竹之内 朋夫, 岩波 義幸1987 年 59 巻 2 号 p. 85-90
発行日: 1987/02/25
公開日: 2011/09/23
ジャーナル フリーFor the production of sound castings it is important to be able to predict the grade of microporosities formed in the center of the castings accompanied with V-segregation. Controlling parameters in computer calculation for the prediction were studied. Experimental work was first conducted where a total of six plate-shaped castings containing different grades of porosities were made by changing the mold taper. The grade of porosity in the castings was judged from radioactive non-destructive tests. The castings were then numerically analyzed and evaluated by means of temperature gradient at solidifying front. However, the critical values differed with the casting size and the grade of porosity could not be related to temperature gradient. The grade of porosity was next evaluated by the shape of the solidifying semi-solid region at the solidifying front. This was done by observing the U-shaped semi-solid region surrounded by iso-solid fraction lines fs=0.3 and fs=0.7. A new parameter L/H was proposed, where L was the central height of the U-shaped region and H was the width of the region at the height of 1/2L. Accordingly the parameter L/H was calculated by computer for each casting and compared with the observed grade of porosity. The region and grade of porosity were correlated well with L/H. The validity of the parameter was checked also on a more sophisticated shaped castings to find a good result. It is concluded that the parameter can be used for a wide variety of castings.抄録全体を表示PDF形式でダウンロード (644K) -
田中 照司, 西山 幸夫, 伊藤 公雄, 福迫 達一1987 年 59 巻 2 号 p. 91-95
発行日: 1987/02/25
公開日: 2011/09/23
ジャーナル フリーAlthough temperature control of exothermic mold for structural control processes is of critical importance, little study has been published on the subject. A study was conducted on actual turbine blade casting to establish a simplified way of controlling the mold temperature. It was found that free control of mold temperature is possible by the use of a parameter P introduced in the present study. A process was proposed to manufacture directionally solidified blades as a higher yield than was possible by the existing process. The process uses a proprietary exothermic material whose temperature is controlled by adjusting the amount of filler to be added into the material.抄録全体を表示PDF形式でダウンロード (667K) -
毛利 勝一, 高木 十三雄, 山口 勝, 柳本 智明1987 年 59 巻 2 号 p. 96-101
発行日: 1987/02/25
公開日: 2011/09/23
ジャーナル フリーEffects of added elements on the intergranular cracking susceptibility of 9%Ni cast steel were investigated. Three series of experiments I to III were carried out. In the series I relation between Ni content and crack susceptibility was examined. By increasing Ni content the steel became embrittled and bending test pieces were readily fractured at a small degree of bending. Microstructural study revealed intergranular cracking already present in the as cast state. In the series II effects of additional elements on crack prevention were studied. Cr, V, Mg, Mo, Zr and Ce were examined to find Zr and Ce effective. In the series III contents of Zr and Ce were changed, further confirming their effects of preventing intergranular cracking. The effect of the two elements was related to the structural refinement occurring on their addition.抄録全体を表示PDF形式でダウンロード (740K) -
河部 昭雄, 若林 太, 小林 俊郎1987 年 59 巻 2 号 p. 102-107
発行日: 1987/02/25
公開日: 2011/09/23
ジャーナル フリーIt is well known that toughness and strength of cast irons can be improved by austempering heat treatment from (α+γ) range. In the present study up to 3% copper was added to ductile cast irons, which were then austempered at 300°C after cooling from various austempering temperatures including (α+γ) range. Effects of the treatments were evaluated by instrumented Charpy impact testing. The best result was obtained by austempering from (α+γ) range. Toughness increased with copper content as far as graphite spheroidization was not adversely affected.抄録全体を表示PDF形式でダウンロード (800K) -
宮沢 信夫, 石野 亨1987 年 59 巻 2 号 p. 108-114
発行日: 1987/02/25
公開日: 2011/09/23
ジャーナル フリーThe finding that sufficient heat resistance against molten cast iron can be obtained by an addition of a small amount of zircon flour or bentonite to dry sand mold with starch phosphate binder led to the development of a new type of a mold for cast iron. The aim of the present study was to investigate high temperature reaction of starch phosphate with zircon flour and bentonite and to discuss the mechanism of heat resistance of the mold against molten cast iron at 1,400°C. The results showed that starch phosphate was decomposed by carburization at high temperature and sodium hydrogen phosphate hydrate (Na2H2P2O7) was condensed into sodium metaphosphate (NaPO3)3. Although sodium hydrogen phosphate did not react at high temperature with zircon flour or bentonite, sodium zircon phosphate (NaZr2(PO4)3) and aluminum phosphate (AlPO4) are formed from sodium metaphosphate at 600°C and the formation of these heat resistant compounds at high temperature gave rise to the heat resistance of the mold.抄録全体を表示PDF形式でダウンロード (762K)
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