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33 巻, 8 号
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研究論文
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―強度に関する現場的一実験―落合 三雄1961 年 33 巻 8 号 p. 553-559
発行日: 1961/08/25
公開日: 2012/10/29
ジャーナル フリーThe vigorous movement of molten metal in the mold cavity of a centrifugal cating tends to cause “wash” and “scab” defects on the cast surfaces. The centrifugal force acting on the metal favors fusion of sand and metal penetration. The factors affecting those defects may be classified as; (1) Vigorous metal movement, (2) Sand grain size, type and amount of binder and type of mold coating, (3) Mold ramming and drying conditions. The molds for centrifugal castings are required to be sufficiently strong at room and high temperature.
The compression strength of actual production molds, prepared with No.7 silica sand and oil binder and dried, was determined at room temperature. The strength value decreased as the mold became more complex. For a simple shaped mold the compression strength was 100 to 170kg/cm2, while for a complex one it was 50 to 100kg/cm2. The strength also decreased as the mold weight increased.
At higher temperature the strength decreased sharply up to 400°C, then gradualy up to 600°C, the value being below 5 kg/cm2 at above 400°C. Hot strengths decreased as the binder ratio was decreased.
A mold coating containing 65% of zirconium silicate (Zr2O3·SiO2) when coated three times, was found to raise the hot strength value of the mold higher than that of a mold not coated or coated only once. Apparently the coating was effective in strengthening the mold.抄録全体を表示PDF形式でダウンロード (665K) -
山崎 桓友1961 年 33 巻 8 号 p. 560-569
発行日: 1961/08/25
公開日: 2012/10/29
ジャーナル フリーAs previously reported by the auther, wear resistance of a cast iron surface is improved greatly by a proper sulfurization in a H2S atmosphere followed by a diffusion treatment. However, the difusion treatment time is too long to be practical. Nitrogen is known to increase the diffusion rate of carbon and sulfur in iron. In order to study the effect nitrogen on the sulfurization process, cast iron was heattreated in H2S-NH3 atmosphere. The samples were examined by means of X-ray analysis, chemical analysis, metallography and hardness measurement. The following results were obtained.
(1) The surface film formed in NH3-H2S atmosphere consisted of pyrrhotite (Fe1-xS) as in the case of H2S atmosphere. The mixed atmosphere containing NH3 over 96% was strongly sulfurizing.
(2) The parabolic law was held in the mixed atmosphere as in the pure H2S atmosphere.
(3) As the NH3 ratio was increased from 0 to 90%, the sulfide film thickness increased. Above 90%, the amount of sulfide decreased rapidly with the increasing NH3.
(4) Sulfur diffused layer of the thickness of 0.05 to 0.15mm was observed beneath the sulfide film.
(5) The position of the hardness peak in the surface layer was different in a NH3-H2S treated iron from that in a H2S treated iron.
(6) The sulfur content in the sulfur diffused layer increased as the NH3 ratio increased at treating temperature below 500°C. On the contrary, at 600°C the sulfur content decreased with the increased ratio of NH3.
(7) It was concluded that a proper amount of nitrogen in the sulfurized layer accelerated the diffusion of sulfur and hence the formation of sulfide on the surface of cast iron.抄録全体を表示PDF形式でダウンロード (994K) -
音谷 登平, 徳永 洋一1961 年 33 巻 8 号 p. 570-578
発行日: 1961/08/25
公開日: 2012/10/29
ジャーナル フリーMolten pig iron containing molybdenum and nickel was treated with an Fe-Si-Mg alloy, cast in a green sand mold and examined for the cast structures and mechanical properties.
Combined effect of chemical analysis and section size on the attainment of an as-cast structure with nodular graphite and acicular matrix was studied and tha results were represented graphically.
The hardness of a nodular-acicular cast iron increased as the section thickness decreased, as the nickel content increased, or as the molybdenum content decreased. This was due to the hardening of the ground mass of austenite containing martensite. Magnetic measurement revealed two different temperature ranges for decomposition of retained austenite during heating of an acicular cast iron. The tensile strength was improved considerably when the iron was annealed at the lower temperature range (250-350°C) for 10 hrs. The optimum toughness of the magnesium-alloy-treated acicular iron was obtained when the as-cast white iron was annealed for the first stage graphitization.抄録全体を表示PDF形式でダウンロード (1014K) -
加山 延太郎, 斎藤 和夫1961 年 33 巻 8 号 p. 579-585
発行日: 1961/08/25
公開日: 2012/10/29
ジャーナル フリーThe melting process in a water-cooled cupola was studied and the feasibility of water-cooling as applied to a small cupola was discussed. The results obtained were as follow.
(1) Excessive cooling tended to shift the site of the oxidizing reaction C+O2→CO2 upwards in the cupola and to counteract the reducing reaction C+CO2→2CO.
(2) The increased rate of cooling in the small water-cooled cupola caused an increase in the oxidizing power of the furnace, an decrease in the melt temperature as tapped, and increases in the losses of carbon and silicon in the furnace.
(3) Combustion condition was improved when the blast was prevented from running along the inside of the water-cooled shell by increasing the tuyer ratio and the blast velocity.
(4) As good operational conditions can be obtained in a small water-cooled cupola as in a standard one, if the cooling is controlled properly and if the coke ratio is increased slightly, an additional advantage of the former being the improved stability of the furnace condition and the melt quality.
(5) A small water-cooled cupola should not be operated without lining.抄録全体を表示PDF形式でダウンロード (711K)
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