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47 巻, 5 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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倉井 和彦, 川野 豊, 山本 悟1975 年 47 巻 5 号 p. 297-304
発行日: 1975/05/25
公開日: 2012/09/18
ジャーナル フリーA small Sn content of 0.002% or 0.03% produced a slight increase in the maximum impact value, but the maximum impact value began to decrease at 0.08%Sn content, and drastically lowered to 1.5kgm/cm2 at 0.11%Sn content. The Sn contents up to 0.03% showed no pronounced effect on the transition temperature. The temperature where impact values began to decrease was lowered slightly at 0.002%Sn content.
A small Pb content, 0.0005%, also produced a slight increase in the maximum impact value. When the Pb content was raised above 0.001%, the maximum impact value decreased remarkably, and at 0.004%Pb content it was as low as 0.9kgm/cm2. Though the transition temperature was slightly raised by increasing the Pb content up to 0.002%, the temperature where the impact value began to decrease was lowered to some degree at 0.001%Pb content.
The beneficial effect to impact properties of very small contents of Sn or Pb appeared to be due to the increased plastic deformation caused by the segregation of these elements having low melting point at grain boundaries, while the detrimental effect of the relatively large content of these elements was related to the inferior shape of graphite particles.抄録全体を表示PDF形式でダウンロード (929K) -
西 成基, 小林 俊郎1975 年 47 巻 5 号 p. 305-312
発行日: 1975/05/25
公開日: 2012/09/18
ジャーナル フリーIn this study, instrumented Charpy impact test was carried out on as-cast flaky and nodular cast irons. Impact fracture behavior in these cast irons was analyzed and fracture toughness was measured mainly following fracture mechanics. Test temperature range (10∼−60°C) in this study seemed to correspond to the lower temperature side of the transition curve. Therefore, remarkable dependence of fracture behavior on temperature was not detected. However, a little reduction of toughness at low temperature was observed in nodular iron, and low stress type brittle fracture was observed in V notch Charpy specimens of both cast irons.
According to the result of analysis on absorhed energy, crack initiation energy was larger than propagation energy in V-notched, double-notched and unnotched specimens. Fracture mode in V- and double-notched specimens was very similar, and it was found that the critical COD value can he determined from the deflection to the maximum unstable fracture load. The fracture toughness values KIC obtained were 71kg·√mm/mm2 for the flaky graphite and 139.5kg·√mm/mm2 for nodular cast irons at room temperature. The critical crack length for unstable fracture was evaluated under various stress levels and flaw shapes. These results provide useful information for the solution of various practical problems.抄録全体を表示PDF形式でダウンロード (968K) -
大和田 野利郎, 山田 恒二, 藤原 真久1975 年 47 巻 5 号 p. 313-319
発行日: 1975/05/25
公開日: 2012/09/18
ジャーナル フリーThe effects of three rate-controlling factors, i.e. graphite nodule number, cooling rate and growth rate constants of the ferrite layer, on the ferritization rate of spheroidal graphite iron on linear cooling were investigated.
The results of experiments on unidirectional growth of ferrite layers show that the growth rate constant of the ferrite layer in direct transformation during cooling is approximately proportional to the undercooling, and that proportional constant and the temperature at which ferritization starts vary with silicon and manganese content in iron. Ferritization of spheroidal graphite iron on linear cooling proceeds, in the beginning, by direct transformation as the undercooling increases, but it due to indirct transformation stops after pearlite is formed. The slower the cooling rate and the greater the graphite nodule number, the bigger is the ferritized fraction at the same undercooling.
Based on these results, the ferritization process on linear cooling was numerically expressed. This was in good accord with the experimental results. By using the expression, the ferritized fraction after cooling can be evaluated.抄録全体を表示PDF形式でダウンロード (725K) -
谷口 希一1975 年 47 巻 5 号 p. 320-325
発行日: 1975/05/25
公開日: 2012/09/18
ジャーナル フリーWhite cast iron consisting of continuous phase of cementite interspersed with rods or globules of austenite is not originally very tough. In order to improve the toughness, the author has studied the hot rolling of brittle white cast iron and evaluated the relationship between the rolling characteristics and rolled structures.
It was found that the plastic working of white cast iron by hot rolling technique was possible. Hot rolling was easier with lower carbon content and higher rolling temperature. The network structures of ledeburite were deformed in parallel with the direction of rolling and dispersed uniformly in the matrix. The tensile strength, elongation and resilience of the rolled white cast iron increased remarkably compared with those of the as-cast ones because of the fine and uniform dispersion of ledeburite.抄録全体を表示PDF形式でダウンロード (885K) -
炭本 治喜, 中村 幸吉1975 年 47 巻 5 号 p. 326-331
発行日: 1975/05/25
公開日: 2012/09/18
ジャーナル フリーWhen the impact value is low in iron and steel, the fracture surface generally presents a white appearance that is called the brittle fracture. However, in highly ductile spheroidal fracture surface iron, it was found that the impact value does not decrease despite the fact that a major part of the fracture surface is white. It is thought that the impact characteristics of the spheroidal graphite cast iron may be explained by considering this phenomenon. The following conclusion was obtained from the observation on mainly the fracture surface after impact testing in different temperatures (−196°C∼100°C).
The fracture surface was classified into three types as follows. 1) Gray fracture surface with high impact value : the deformation of the matrix is large, and the internal fracture of graphite is also evident. 2) White fracture surface with high impact value : the deformation of the matrix is large, but the internal fracture of graphite is slight. 3) White fracture surface with low impact value : the graphites are sharply cut and large cracks are found in the matrix, and also some twins are found near the fracture surface. It is considered that the high impact value in the second type of fracture have been obtained due to the large deformation of the matrix prior to brittle fracture.抄録全体を表示PDF形式でダウンロード (890K) -
山田 始, 田中 他喜男1975 年 47 巻 5 号 p. 332-337
発行日: 1975/05/25
公開日: 2012/09/18
ジャーナル フリーThe machinability of AC3A and hypereutectic alloy as typical alloys of Al-Si casting alloys on super-high speed machining at 1,000m/min were examined.
In the machining of AC3A, the finished surface was remarkably improved and cutting resistance was lowered by super-high speed machining. The effect of cutting fluid such as soluble oil on the decrease of tool wear was notable even on super-high speed machining. Modification treatment with Na was also effective in decreasing the tool wear. Therefore, super-high speed machining of AC3A can be put to practical use.
Frank adhesion in the machining of hypereutectic Al-Si alloy occured at cutting speeds faster than about 300m/min and increased with increasing cutting speed and, however, decreased on super-high speed machining. The cutting resistance of hypereutectic Al-Si alloy remarkably increased with increasing cutting speed because the tool wear depended very much on the cutting speed.抄録全体を表示PDF形式でダウンロード (898K) -
田中 雄一, 本間 恒夫, 井川 克也1975 年 47 巻 5 号 p. 338-344
発行日: 1975/05/25
公開日: 2012/09/18
ジャーナル フリーAlternate bending fatigue tests were carried out on cast iron with various graphite and matrix structures. In order to study fatigue crack initiation and its growth rate, a fatigue machine with a microscopic cine-camera installed was employed for continuous and direct observation of the polished surface of the specimen during fatigue. The fatigue strength, endurance ratio and fatigue notch factor obtained by alternate bending fatigue tests of the small and thin specimens of cast iron were in good agreement with the results of rotating beam fatigue tests by many workers.
In the spheroidal graphite cast iron, the analyses for growth of fatigue crack showed that there were three stages of growth involved. The first stage is the region where the rate of crack growth decreases with fatigue crack propagation, which was related to stress relaxation at the notch root by micro-crack growth. It was found that the fatigue crack propagation was arrested in the spheroidal graphite. The rate of growth (da/dN) in the second stage was related to the stress intensity factor (Kamp) and could be expressed by
da/dN=C·(Kamp)4
In the third stage, the most rapid crack propagation (which could be expressed by da/dN=C·(Kamp)8∼10) was achieved by the linking of isolated micro-cracks generated from graphite nodules ahead of the main crack. In the flaky graphite cast iron, micro-crack growth initiated from flaky graphite rather than notch root and it linked up together just before fracture.抄録全体を表示PDF形式でダウンロード (989K)
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