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57 巻, 3 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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解説
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第3部 我が国の生産動向編集委員会1985 年 57 巻 3 号 p. 152-155
発行日: 1985/03/25
公開日: 2015/01/27
ジャーナル フリーPDF形式でダウンロード (1825K)
研究論文
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柳沢 平, 呂 傳盛1985 年 57 巻 3 号 p. 156-162
発行日: 1985/03/25
公開日: 2011/11/17
ジャーナル フリーThe tensile flow stress of ferritic spheroidal graphite cast iron can be expressed by the following equation as the function of graphite volume fraction Vg and ferrite grain size df.σz=k3(1−k1Vg) (σ0+k2df−1/2)The relationship between tensile flow stress σz by the analysis of plastic deformation and volume fraction of graphite is approximated by the same formula as the above equation. It shows that the validity of the present assumptions. It was clarified that the flow stress of ferritic spheroidal graphite cast iron is influenced appreciably by the ferrite grain size and the triaxial stress field developed in the ferritic matrix between graphite nodules.抄録全体を表示PDF形式でダウンロード (692K) -
山田 聡, 久保田 博, 加藤 栄一1985 年 57 巻 3 号 p. 163-167
発行日: 1985/03/25
公開日: 2011/11/17
ジャーナル フリーApplication of phenol urethane cold box cores to steel castings is often associated with gas defects like pinholes. This effect of the cold box cores on the defects was clearly indicated by the experiments in which the same steel melt was poured into molds with cold box cores or CO2 process cores, that is, much more pinholes were observed in the castings when cold box cores were used. The concentration of nitrogen in the samples obtained from the portions close to the pinholes was much higher than those in other portions of the casting. Mass spectrometric analysis of the gases evolved from the cold box, CO2 process and Shell mold process (resol-type) core sands was performed in the temperature range from 600°C to 1,400°C. As the cold box core sands were heated, the solvent of the binder for them volatilized firstly, followed by the evolution of NH3, CO2, CO, H2O and various kinds of hydrocarbon compounds produced by the decomposition of the binder. In the gases from other core sands, NH3 was not detected. It is concluded that the pinholes were caused by the reaction between cast steel and NH3 evolved from the cold box cores. Thermodynamic calculation indicates that the nitrogen pressure of NH3 is very high, and then liquid steel can absorb large amount of nitrogen from NH3.抄録全体を表示PDF形式でダウンロード (539K) -
田保 昭典1985 年 57 巻 3 号 p. 168-173
発行日: 1985/03/25
公開日: 2011/11/17
ジャーナル フリーThe static stress-strain relationship for gray cast irons has a curvature in low stress levels. Therefore, the elastic behavior is not found clearly. Measurements of the Young's modulus of cast irons with various structures of graphite and matrix were carried out both statically and dynamically. The transverse vibration testing was used as the dynamic method. The dynamic Young's modulus depends on strain and stress amplitude. The amplitude dependence increases as Young's modulus decreases. The static and dynamic Young's modulus have a good coincidence in the same stress values. In this case, values of the maximum stress are used in the dynamic Young's modulus. The dynamic Young's modulus depends on neither the natural frequency nor strain rate. The surface strain distribution in the pieces tested dynamically was calculated from the theory in the first mode of vibration, and it was confirmed by experiments that the surface strain distribution of the cast iron which Young's modulus changes with stress is the same as that of steel with constant modulus. The Young's modulus is principally dependent on the graphite shape. It is considered that the plastic deformation occured microscopically by high stress concentration at the edges of graphites. The elastic behavior could be more easily examined by the dynamic testing.抄録全体を表示PDF形式でダウンロード (624K) -
松浦 誠, 片島 三朗1985 年 57 巻 3 号 p. 174-179
発行日: 1985/03/25
公開日: 2011/11/17
ジャーナル フリーThe effect of air flow rate (rate of increase in air pressure applied onto molding sand) on sand compaction was studied by the measurements of compaction force and mold density in the process of air flow pressing. Under the condition of higher air flow rate, an impulsive compaction force was observed immediately after the pressure was applied, resulting in high compaction of molding sand. The impulsive compaction force increased with increase in air flow rate, then the mold density also increased. The dynamic movement of molding sand during compaction was also measured with an accelerometer to investigate the mechanism of sand compaction in high air flow rate. The molding sand is moved downward in high speed by rapidly increasing air pressure and pressed toward the pattern plate instantaneously and intensively. At that time, the impact compaction occurs accompanying with an impulsive force. The distribution of the compaction force in the mold was theoretically analyzed by considering these dynamic compaction behaviors.抄録全体を表示PDF形式でダウンロード (630K) -
沢本 章, 大城 桂作, 松田 公扶1985 年 57 巻 3 号 p. 180-186
発行日: 1985/03/25
公開日: 2011/11/17
ジャーナル フリーFe-5%Cr and Fe-15%Cr alloys with 1.0% to 4.5%C and 0% to 35%W were solidified unidirectionally in the exothermic sand mold (φ30mm×70mm) on a water-cooled copper chilling plate. The species of primary and eutectic carbides were identified by etching and X-ray diffraction methods, and the amounts of carbides were quantitatively measured by using of an image analyzer. The constitutional diagrams of primary crystals and the solidification processes were studied by thermal analysis and quenching methods. The distributions of chromium and tungsten in each phase were also analyzed with EPMA to examine the behavior of the elements during solidification.
In Fe-5%Cr-W-C alloys, δ, γ, ε, M6C and M3C crystallized as primary phase corresponding to the alloy compositions and Liquid→γ+M6C, Liquid→γ+M6C+M3C and Liquid→γ+M3C eutectic reactions occurred. Primary δ, γ, ε, M6C and M7C3 appeared and Liquid→γ+M6C, Liquid→γ+M6C+M7C3 and Liquid→γ+M7C3 eutectic reactions took place in Fe-15%Cr-W-C alloys. Eutectic M6C crystallized in riblike or fishspinelike shape and primary M6C did dendritically. The amount of M6C increased and those of M3C and M7C3 decreased as tungsten content of the specimen increased. Distribution ratios of chromium and tungsten to primary austenite were 0.9 to 0.6 and 0.6 to 0.4, respectively. They decreased with increase in carbon content of specimens. Chromium was preferentially partitioned to M7C3 or M3C and tungsten to M6C.抄録全体を表示PDF形式でダウンロード (886K) -
村本 和夫, 菊池 千之, 佐藤 一雄1985 年 57 巻 3 号 p. 187-192
発行日: 1985/03/25
公開日: 2011/11/17
ジャーナル フリーMicrostructures and mechanical properties of heat-affected zone of spheroidal graphite cast iron have been investigated by using heat cycle simulating equipment on the assumption of practical welding process. The matrix structure of heat-affected zone at room temperature is classified either martensite, troostite including small amount of martensite or pearlite, depending on the cooling time from 1,000°C to 300°C. That is, martensite matrix, troostite matrix and pearlite matrix were obtained at cooling times of less than 80s, 80-300s and longer than 300s. respectively. Vickers hardness, Charpy impact value and tensile strength of those matrices are always found to be similar to or greater than those properties of the as-cast base metals whenever the cooling time from 800°C to 500°C is longer than 100s.
The structures of matrices for the heat-treated material were different from that for the base metal when the highest temperature in the heating cycle was higher than 700°C. When the highest temperature of heating cycle was around 900°C, its Charpy impact value reached to maximum. For the air-cooled materials, the tensile strength increased with increasing the highest temperature of heating cycle. In the repeated heating and cooling process with lower temperature of 300°C, even though the cooling time was changed, the apparent difference in each mechanical property could not been recognized. Charpy impact values and tensile strengths for the materials in the repeated heat process increased by 25% and 10%, respectively, from those for the base metals.抄録全体を表示PDF形式でダウンロード (781K)
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