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Tamura Y.,Chiba Institute of Technology | Sugimoto Y.,Chiba Institute of Technology | Sugimoto Y.,Kimura Chuzosho Co. | Soda H.,University of Toronto | McLean A.,University of Toronto
Keikinzoku/Journal of Japan Institute of Light Metals | Year: 2013

Cast Mg-Ca and Mg-Ca-Zr alloys were prepared from elemental metals, Mg-5Ca, and Mg-33Zr master alloys. The microstructure was examined and tensile tests performed. The microstructures of the cast Mg-Ca alloys consist of primary α-Mg dendrites and a degenerated lamellar eutectic. An addition of zirconium transformed coarse primary α-Mg dendrites to fine globular grains of approximately 20~35 μm in diameter. Hardness increased for both Mg-Ca and Mg-Ca-Zr alloys with calcium contents, and there was a slope change in hardness increase at about 0.3%Ca, at which eutectic containing Mg 2Ca started to appear at grain boundaries. The value of 0.2% proof stress also increased for both alloys, showing higher values due to a grain refining effect. The values of tensile strength for Mg-Ca-Zr alloys were also higher than those of the Mg-Ca alloys, while the strength did not improve beyond 0.3%Ca. Fracture occurred owing to the decohesion within eutectic regions and the cracks propagated though the regions. Thus, an increase in the eutectic regions leads to a reduction in ductility. In particular, the Mg- Ca-Zr alloys, with calcium content as little as 0.3%, showed a significant reduction in ductility, negating the effect of grain refinement. © 2013 The Japan Institute of Light Metals. Source

Kimura H.,Kimura Chuzosho Co.
71st World Foundry Congress: Advanced Sustainable Foundry, WFC 2014 | Year: 2014

Our company introduced Full Mold Casting (FMC) in 1966, and have been innovating its technology. I will report the action contents. Although FMC was an excellent technology to produce complex castings, many defective products occurred by the residue of polystyrene pattern. Therefore, in order to prevent the residue, we developed the technology of decreasing it. Also, in order to reproduce the pattern of defective products promptly, we founded the pattern shop in 1967, the following year of FMC introduction. When the First Oil Shock occurred at the end of 1973, we promoted technological innovation of FMC with using non work hours which was caused by the recession. As a result, we developed "New Full Mold Casting (NFMC)" and started to manufacture the castings of machine tools. From 1976, we discontinued cavity mold process, and converted to FMC completely. In 1981, we founded "Japan Metal Co., Ltd. with the aim of "Clean foundry", and in 1988, we founded the foundry in Omaezaki for manufacturing large castings. The technological development of Kimura advanced greatly by construction of new plants in this way. Through the introduction of CAD/CAM, the development of coating, automatic measurement of the cut styrolfoam pattern with the laser measuring machine, and shortening the cooling time of casting production by the introduction of the water cooling system, we could started the casting series production. When amount of production decreased dramatically (2009) after Lehman shock, we developed the casting technology for engine block by FMC. Also, we developed hybrid casting process which using the integrated core manufactured with RP (Rapid Prototyping) technology, and wrapped it with the main mold of formed pattern. In addition to this, we have forwarded our human resource to develop the simulation. FMC which we have been working on was an unestablished technology, so it needed the constant development. It was lucky for us to have a task defined challenge and technological innovation for the technical establishment of FMC. Source

Motoyama Y.,Waseda University | Takahashi H.,Waseda University | Takahashi H.,Package Group | Okane T.,Japan National Institute of Advanced Industrial Science and Technology | And 2 more authors.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2013

The prediction of residual stress in a stress lattice shape casting (stress lattice) has been conducted and discussed by some researchers via the Finite Element Method (FEM). However, most of the previous studies used the first-order tetrahedral element, which has poor analysis accuracy in problems including bending. The use of the first-order tetrahedral element makes the verification of these studies uncertain because the bending deformation essentially occurs in the stress lattice casting. This study first shows that the thermal stress analysis for the stress lattice should use the element that can represent the bending deformation in principle for bending of the thin parts. Second, the simulated residual stress was compared with the measured value. The thermal stress analysis successfully predicted the residual stress of the stress lattice casting with and 11 pct difference. In addition to the prediction of the residual stress, it is important from the viewpoint of the productivity of castings to reveal the effect of the shake-out temperature on the residual stress. However, in the previous studies, conclusions concerning the effect of the shake-out temperature on the residual stress were not consistent (i.e., the one study said the higher shake-out temperature decreased the residual stress, and another study said a higher shake-out temperature increased the residual stress). Therefore, the current study first discusses the reason for the inconsistent conclusions in the previous studies. Second, stress lattice castings were cast and shaken out at various shake-out temperatures. Then, the current study validated the effect of the shake-out temperature on the residual stress. Consequently, the experimental results supported the conclusion of Kasch and Mikelonis that the shake-out at higher temperature contributed to the increase of the residual stress in the casting. © The Minerals, Metals & Materials Society and ASM International 2013. Source

Morito S.,The University of Shimane | Iwami Y.,The University of Shimane | Koyano T.,Kimura Chuzosho Co. | Ohba T.,University of Tsukuba
Materials Transactions | Year: 2016

Microstructures of lath martensite that contains bcc or bct martensite crystals in Fe-C alloys are known to depend on the carbon content of the alloys. The effect of nitrogen content on microstructure, however, has not yet been elucidated. This study elucidates the effects of carbon and nitrogen content on microstructures via local crystallographic analysis. We found that the packet sizes are similar when the nitrogen content in the alloys are the same as the carbon content, with the packet size decreasing with increasing carbon and nitrogen content. The block and subblock thicknesses in low nitrogen lath martensite are smaller than those in low carbon lath martensite, whereas those in medium and high carbon and nitrogen lath martensites are similar. Martensite lath thickness and dislocation density in the Fe-N alloy laths are lower than those in the Fe-C alloys laths, and the distribution of misorientation angles between adjacent the blocks and sub-blocks in Fe-N alloys is similar to that in Fe-C alloys. © 2016 The Japan Institute of Metals and Materials. Source

Kimura Chuzosho Co., Mie Prefecture, Senshu Corporation, Naniwa Roki Co., Hitachi Ltd. and Kinoshita Manufactory Co. | Date: 2011-01-24

There is provided a method for obtaining a pure melt in which the impurities Mn, Al, Ti, Pb, Zn, and B are removed from molten cast iron and depletion of useful C and Si is suppressed, the method wherein an excess oxygen flame having a theoretical combustion ratio of fuel and oxygen (amount of oxygen (volume)5/amount of fuel (volume)) of 1 to 1.5 is directly exposed to the surface of pre-melted molten cast iron, the temperature of the molten cast iron is held at 1250 C. or more and less than 1500 C. while the melt surface is superheated and an acidic slag is brought into contact with the melt, and an oxygen-containing gas is injected into the interior of the molten cast iron.

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