鋳造工学
Online ISSN : 2185-5374
Print ISSN : 1342-0429
ISSN-L : 1342-0429
80 巻, 3 号
選択された号の論文の5件中1~5を表示しています
研究論文
  • 趙 柏榮, 上野 勝司, 山田 聡, 中江 秀雄
    2008 年 80 巻 3 号 p. 149-155
    発行日: 2008/03/25
    公開日: 2014/02/21
    ジャーナル フリー
      The matrix of cast iron is usually pearlite and ferrite. There are two types of pearlite; namely lamellar and granular. Recently, only the lamellar is called pearlite and granular is called spheroidite. This paper discusses the formation mechanism of both types using the granular types.
      The influence of P, Sn, and heat treatments on matrix structures in nodular cast irons (chemical composition is 3.65%C -2.5%Si -0.3%Mn -0.04%Mg) were studied. Group P added with 0mass% to 0.2mass% P and Group Sn added with 0mass% to 0.06mass% Sn were studied. The samples were heat-treated to obtain spherical pearlite in matrix structures using method A (heated to the intermediate temperature between Ac1 and Ar1) and method B (two step heat treatment).
      The results of these experiments showed that the matrix structure of cast sample to be lamellar pearlite. The matrix of samples treated by method A was spherical pearlite When the spherical pearlite observed in optical micrographs (2-dimentional morphology) were stereographically observed by SEM, the morphology was found to be stick-like cementite in samples heat-treated at 973K, 1023K, and coral-like cementite heat-treated at 1073K.
      The forming conditions of stick-like were pound to be related to the content of dissolved carbon in austenite. This investigation shows that spherical pearlite is obtained at heating temperatures between Ar1 and Ac1.
  • 八百川 盾, Farshid Pahlevani, 安斎 浩一, Perakit Viriyarattanasak, 板村 正行
    2008 年 80 巻 3 号 p. 156-163
    発行日: 2008/03/25
    公開日: 2014/02/21
    ジャーナル フリー
      Semi-solid casting techniques can offer high mechanical properties and low porosity. Many commercial semi-solid processes have therefore been developed over the past three decades in order to manufacture high quality castings. The quick semi-solid slurry production method (Cup-cast method), which can prepare semi-solid slurry quickly by pouring melt into a metallic cup without the need for any expensive facilities, is one such novel semi-solid process. With this technique, pouring conditions and cup design affect temperature distribution in semi-solid slurry. The aim of this study was to investigate the effects of stirring melt at the pouring stage and cup materials on inhomogeneous temperature distribution in JIS-AC4CH aluminum alloy semi-solid slurry. Temperature measurement experiments and numerical simulations were conducted with different sizes and materials of cylindrical metallic pipes. The experimental results showed that the temperature of the semi-solid slurry at the top was lower than that at the bottom for carbon steel and cast iron pipes at 60 seconds after the start of pouring, while opposite temperature distribution was obtained when copper pipes were used. It was found that the semi-solid slurry temperature at the top decreased with increasing thermal diffusivity of pipe material and with increasing degree of stirring.
  • 平塚 貞人, 堀江 皓, 小綿 利憲, 中村 満, 晴山 巧
    2008 年 80 巻 3 号 p. 164-169
    発行日: 2008/03/25
    公開日: 2014/02/21
    ジャーナル フリー
      Upset welding of spheroidal graphite cast iron was carried out under various welding conditions. The diameter of the specimen was 10mm in diameter and 100 in length. Microstructure observation was employed in order to clarify the characterization at welding interface. Vicks hardness, tensile strength and elongation of joint were investigated. In the upset welding, the melted part on the joint was exhausted to the edge side, and the part becomes mottle structure. The microstructure on the joint becomes a spheroidal graphite cast iron structure in the pearlite matrix from the mottle structure with increasing heat input. When the melted part on the joint was exhausted to the edge side, the part where the spheroidal graphite coheres to the center part of the sample was observed
  • 鮫島 大湖, 野口 徹, 堀川 紀孝, 中村 孝, 桃野 正
    2008 年 80 巻 3 号 p. 170-176
    発行日: 2008/03/25
    公開日: 2014/02/21
    ジャーナル フリー
      Thin wall ductile cast iron is a promising material for reducing the weight of industrial products. To utilize this cast iron, mechanical properties have to be established. This report deals with the fracture toughness of thin castings with which CT test pieces cannot be obtained. We therefore focussed on the SP test which requires 0.5mm thickness test pieces. In the tests, a 2.4mm diameter bearing steel ball was indented into the test piece until it broke, and the load and displacement were measured. A drop in the load indicated the breaking of the test piece, and the equivalent fracture strain εqf was evaluated from the displacement δ* up to the point of breaking. There was a correlation between the fracture toughness JIC and equivalent fracture strain εqf in several materials, and the fracture toughness was estimated from the correlation. CT and SP tests were conducted on the same block of ductile cast iron, and the fracture toughness JIC and equivalent fracture strain εqf were measured and compared. In the SP test on ductile cast iron, the fracture point on the load-displacement curve was not certain. To determine the point on the curve, the fracture process was considered from the fracture appearance observation. The equivalent fracture strain εqf was evaluated from the fracture displacement δ*. The correlation between the fracture toughness JIC and equivalent fracture strain εqf was determined as JIC = 400εqf2 + 5 [kJ/m2]. It was established that the fracture toughness of thin wall castings can be measured by the SP test.
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