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後続誌
52 巻, 6 号
選択された号の論文の6件中1～6を表示しています
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研究論文
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柳沢 平, 丸山 益輝, 有井 一善, 石谷 凡夫, 小西 正明1980 年 52 巻 6 号 p. 331-336
発行日: 1980/06/25
公開日: 2012/03/28
ジャーナル フリーAs the temperature increases, the tensile strength decreases gradually up to 350°C at the strain rate έ of 2.8×10-4 sec-1 and up to 400°C at the strain rate έ of 1.4×10-2 sec-1 and it falls down abruptly above these temperatures. The elongation of rupture decreases, as the temperature increases. The temperature at which the elongation becomes smallest is 400°C at έ=2.8×10-4 sec-1 and 500°C at έ=1.4×10-2 sec-1. This brittleness is due to intergranular fracture. As the temperature increases, the fatigue strength of 104, 105 and 106 cycles in rotary bending fatigue test decreases gradually up to 500°C while it decreases more rapidly above 500°C. However, the fatigue limit decreases gradually, as the temperature increases. The great fall in the fatigue strength at 500°C is found only when the intergranular fracture occurs. Both the striation and the intergranular fracture are found in the specimens of fatigue tests at 400°C.
The mechanism of intermediate temperature embrittlement by the intergranular fracture was considered relating to the dynamic strain aging. In this experiment, the temperature of dynamic strain aging did not agree with that of intergranular fracture. The difference of the temperature is assumed to be due to the increase in the strain rate at the local necking of the matrix between the spheroidal graphites.抄録全体を表示PDF形式でダウンロード (693K) -
松田 政夫1980 年 52 巻 6 号 p. 337-343
発行日: 1980/06/25
公開日: 2012/03/28
ジャーナル フリーThere is a method using semilogarithmic graph paper known as the graphical analysis method to analyze heat conduction in a cylinder. This method is sometimes troublesome because the logarithmic scale has to be transformed into a normal scale after semilogarithmic plotting. In the new method of graphical analysis shown in this work, nornal scale section paper can be used by adding supplementary lines before plotting. The principle of this method is based on the one dimentional difference equation of the polar coordinates, in which difference of the time Δt is defined as follows : Δt=Δr2cγ/4λ, where Δr is the difference of the radial distance, c is the specific heat, γ is the specific weight and λ is the heat conductivity of the cylinder. Therefore, this new method can be easily converted to simple numerical calculation.
When the front of the molten metal passes through the mold cavity, a thin solid metal layer covers the surface of the cavity everywhere. The average temperature θm at the cross section of the molten metal flowing inside the metal layer is expressed by the equations approximately :
Θm=1 −2√τ⋅⋅⋅⋅⋅⋅τ<0.063 Θm=0.72 exp (−5.82τ)⋅⋅⋅⋅⋅⋅τ>0.063
where Θm=(θm−θf)/(θp−θf), θf is the melting point, θp is the initial temperature of the molten metal with an uniform temperature distribution and τ is the dimentionless time defined by the expression (λ/cγ)t/r?? in which t is the time.抄録全体を表示PDF形式でダウンロード (711K) -
倉部 兵次郎, 村松 晃, 牧口 利貞1980 年 52 巻 6 号 p. 344-349
発行日: 1980/06/25
公開日: 2012/03/28
ジャーナル フリーA water soluble CO2 gas mold in which sodium aluminate was mixed in alumina sand used as a refractory particle to facilitate the disintegration of the mold by water spray was tested for the purpose of investigating its high temperature characteristics. After adding to alumina sand sodium aluminate of 5 percent with Na2O/Al2O3 mole ratio of 1.5 and 50% water, the water soluble mold was made in two ways : one was by conventional hardening with long CO2 gassing time and another was hardened by short gassing time after mixing in CO2 atmosphere, i.e., pre-gassing.
Mold treated by pre-gassing was more water soluble than conventional one under 700°C. At temperatures above 700°C, both molds showed excellent disintegration by water spray, which seems to be due to the formation of sodium aluminate from alumina gel and sodium carbonate. The maximum compression strength of this mold was about 30kg/cm2 at 300°C to 500°C which subsequently decreased to about 10kg/cm2 at the temperature range of 700°C to 1,300°C. X-ray diffraction analyses of the mold heated at 900°C to 1,300°C showed predominantly alumina and sodium aluminate patterns, but a weak trace of β-alumina, Na2O⋅11Al2O3, was detected on the surface of the alumina sand heated at above 1,200°C after washing by water.抄録全体を表示PDF形式でダウンロード (603K) -
山岡 弘1980 年 52 巻 6 号 p. 350-355
発行日: 1980/06/25
公開日: 2012/03/28
ジャーナル フリーDecomposed gas from the sand mold bound with organic resin often induces blowhole defects in steel castings. The new casting process was developed to prevent blowhole defects by sucking the decomposed gas with air from the mold surface without letting it dissolve into the molten steel. In this process, the problem of blowhole defects, which are generally found in cast steel produced by the shell mold process or the process using urea-furan resin bound sand mold have been overcome and a sound steel casting can be obtained. It was found that this casting process is also applicable to green sand mold with the same effect as in the organic resin bound sand mold.抄録全体を表示PDF形式でダウンロード (587K)
技術報告
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前田 憲一郎1980 年 52 巻 6 号 p. 356-361
発行日: 1980/06/25
公開日: 2015/01/27
ジャーナル フリーPDF形式でダウンロード (3081K) -
野口 紘, 松居 進, 片江 隆行1980 年 52 巻 6 号 p. 362-367
発行日: 1980/06/25
公開日: 2015/01/27
ジャーナル フリーPDF形式でダウンロード (3084K)
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