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62 巻, 8 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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研究論文
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岸武 勝彦, 永井 恭一1990 年 62 巻 8 号 p. 620-624
発行日: 1990/08/25
公開日: 2011/07/27
ジャーナル フリーThe effects of modification and spheroidizing of Si on the electrical resistivity were investigated in order to clarify the relation between the morphology of silicon and the electrical resistivity in Al-Si alloy castings. The specific resistivity of both unmodified and modified (sodium-treated) Al-Si alloy castings increases with increasing the Si content. The specific resistivity is decreased by the modification and the resistivity difference increases with the Si content. Therefore, the measurement of electrical resistivity could be used to judge the modification effect of Al-Si alloy castings. The specific resistivity of hypereutectic Al-Si alloy castings is hardly changed by phosphorus-treatment, but decreased largely by sodium-treatment. The specific resistivity of both unmodified and modified specimens decreases after stabilizing treatment at 300°C for 10 hours and comes to be linear to the Si content. The specific resistivity of the spheroidized and stabilized specimens is lower than that of the specimens which are only stabilized.抄録全体を表示PDF形式でダウンロード (817K) -
相馬 詢, 若松 克光1990 年 62 巻 8 号 p. 625-630
発行日: 1990/08/25
公開日: 2011/07/27
ジャーナル フリーIn order to elucidate the effect of direct and indirect graphitizations on growth of cast iron, tests on flake graphite cast iron were carried out in critical range (850∼650°C) by cyclic heating including isothermal heating at various temperatures in cooling transformation range and below it. The results obtained were as follows ;
(1) The iron expanded remarkably by isothermal heating just below the beginning of cooling transformation (730°C) and the growth increased with much ferrite around graphite flakes. This was mainly due to direct graphitization.
(2) With lowering isothermal heating temperature, the expansion by direct graphitization decreased gradually and in the lower parts from the middle point of critical range, the main mechanism of graphitization became indirect and growth decreased. Microphotographs showed the disintegration of pearlite was brought about at the surface of graphite selectively.
(3) The growth of 730°C isothermal heating was the maximum and the growth of 680°C, 700°C, 715°C isothermal heating and simple cyclic heating followed it. But, when the austenite growth was deducted, 680°C isothermal heating was the maximum though the amount of ferrite was less than 730°C isothermal heating. This was considered to be the remarkable tendency of graphite re-precipitation by indirect graphitization.
(4) It could be explained from the standpoint of the theory of irreversible graphite migration that it was also important added to the former method to consider central temperature range of direct and indirect graphitizations of selected cast iron and heating conditions for further increase of heat-resistance in critical range.抄録全体を表示PDF形式でダウンロード (793K) -
阿部 利彦, 川原 正弘, 井川 克也1990 年 62 巻 8 号 p. 631-636
発行日: 1990/08/25
公開日: 2011/07/27
ジャーナル フリーA quality of an ultrasonic internal image have been improved by using both a large amount of image memory and a computer technique. Ultrasonic image of internal defect in cast iron was investigated in this paper by comparing with a X-ray method. A shape and a depth of internal defects were measured by the ultrasonic image analyser using 5 or 10 MHz point focused immersion type transducer. As a focusing of the transducer was important, the relation between optimum focus distance and depth of a defect through dipped water was derived as an equation (1).
Z=f+t-0.338v2x=f+t-0.676dv(mm) (1)
where Z : optimum distance from a bottom of a specimen to top of a transducer (mm), f : focal length in water (mm), t : thickness of a specimen (mm), v : ultrasonic sound velocity in cast iron (km/s), x : time for a sound propagation from surface to defect (μs), d : depth of a defect (mm), t : thickness of a specimen(mm).
A projected shape of a large defect such as a shrinkage cavity was easily observed by using the bottom reflected wave image from a casting rough surface. A defect shape at an arbitrary depth was obtained with a good depth resolution by using the defect reflected wave image. Surface roughness affected on a quality of the image by inducing a noise signal. Thus the rough surface of an as-cast sample had to be ground for the observation of a small cavity image with less than 1mm diameter. As a result of these observations, most of small cavities were observed just below the upper surface and just above the bottom surface in as-cast specimens.抄録全体を表示PDF形式でダウンロード (850K) -
宮沢 信夫, 佐々木 洋, 呉 凌1990 年 62 巻 8 号 p. 637-642
発行日: 1990/08/25
公開日: 2011/07/27
ジャーナル フリーMold containing high viscous phosphatic starch (eg. 420 c. p.) and small amount of heat-stable material, by process of adding starch-water past to sand, has been reported to be applicable for cast iron. In this investigation, to omit a process of pasting starch in a solution, a technique that powdery low viscous phosphatic starch (20 c. p.) was mixed to sand directly, and a “vaccumed-air dehydration process” that air is vaccumed from and passed to the mold, were contrived. Dehydration tests of the mold by various drying process were performed to obtain a relation among factors such as vaccumed-air duration, residual water and strength of the mold. The relation was found to be hold independent on the mold drying process.抄録全体を表示PDF形式でダウンロード (779K) -
堀江 皓, 小綿 利憲, 福井 克彦, 石川 佳樹1990 年 62 巻 8 号 p. 643-647
発行日: 1990/08/25
公開日: 2011/07/27
ジャーナル フリーThree hundred grams of Fe-C-Mn (1.5%) alloy in an electrode graphite crucible was melted in an induction furnace, maximun 20% potassium sulfide was added onto the surface of the molten metal at 1400°C.
After various holding time, the melt was poured into iron mold to determine the content of manganese and sulfur.
Microscopic observation and electron probe X-ray microanalysis (EPMA) have been used in order to clarify the reaction product in these specimens.
The addition of potassium sulfide to molten iron could remove a large amount of manganese ; i. e., about 80% manganese could be removed by using a 7.5% additions of potassium sulfide. The rate of manganese removal from molten iron to slag was very rapid.
A large number of polygon reaction products and blow holes with diameter about 200μm or more were observed in the specimen quenched into water after potassium addition.
Quantitative EPMA showed that these reaction products were manganese sulfide.
It is suggested that manganese in molten iron and sulfur in potassium sulfide interact, forming manganese sulfides and these move rapidly to the surface by attach to rising potassium gas bubbles.抄録全体を表示PDF形式でダウンロード (817K) -
高野 憲三, 名取 義勝1990 年 62 巻 8 号 p. 648-653
発行日: 1990/08/25
公開日: 2011/07/27
ジャーナル フリーThe relation between the amount of dehydration and the strength properties of the CO2 silicate moulds hardened by vacuum gassing technique has been investigated, by using a tightchamber in which mould could be stored in humidity controlled atomospheres or in drying reagent i. e. silica gel.
The strength of moulds depend on its water content, the maximum strength can be obtained with the optimum water content in the mould. And also the optimum water content depends on the reaction time with CO2.抄録全体を表示PDF形式でダウンロード (662K) -
佟 慶平, 鈴木 俊夫, 梅田 高照, 加藤 治1990 年 62 巻 8 号 p. 654-659
発行日: 1990/08/25
公開日: 2011/07/27
ジャーナル フリーThe influence of chemical composition and microstructure on the mechanical properties was investigated for high chromium cast irons with various carbon, chromium, silicon, nickel and molybdenum contents. Both of the tensile strength and the fracture toughness depend on the Cr/C ratio and the area percentage of eutectic carbides. The hardness depends, however, only on the eutectic carbide amount when matrix is martensite. The larger the eutectic carbide amount the higher the hardness. Both the tensile strength and the fracture toughness are larger in the range of Cr/C ratio 4-8 while smaller in the range with Cr/C ratio larger than 8 or smaller than 4. For alloys with a constant Cr/C ratio, both the tensile strength and the fracture toughness decrease with increase of the eutectic carbide amount.
There is little effect of nickel content on the tensile strength and the fracture toughness. Also, the tensile strength is not or slightly affected by increasing silicon content, however, the fracture toughness decreases largely when silicon content is larger than 2% . With increase of molybdenum, both the tensile strength and fracture toughness decrease while hardness increases.
The average spacing of eutectic carbides becomes smaller with increasing cooling rate during solidification though the eutectic carbide amount keeps constant for an alloy with a constant chemical composition. The mechanical properties are markedly improved by refining microstructure.抄録全体を表示PDF形式でダウンロード (913K)
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