Spheroidal graphite cast iron was locally hard-faced with inserted hard alloy powder by an evaporative pattern casting process. The vertical cross-section of the inserted layer was examined on the microstructure with EPMA and the hardness with a Vickers hardness tester. It was confirmed that an inserted layer of about 3 mm in thickness could be formed without any defects at the interface of the spheroidal graphite cast iron. The inserted layer was formed with the penetration of the molten cast iron among WC particles in the hard alloy coating. The matrix metal of inserted layer showed a gray cast iron microstructure due to the hindrance to spheroidization caused by the reaction of the molten cast iron with the W and Co elements in the hard alloy.
  The hardness of spheroidal graphite cast iron was about HV200, while the inserted layer exhibited a hardness of HV600 to 1400. The present method using the evaporative pattern casting is therfore considered to be very effective for selective hard facing of spheroidal graphite cast iron.

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  Characteristics of heat treatment for flake graphite cast iron and spheroidal graphite cast iron not containing Ni, Cr, Mo and other elements which affect the hardenability of cast iron were studied.
  The characteristics of heat treatment for these cast irons can be summarized as follows, 1) The heat treatment characteristics of flake graphite cast iron and spheroidal graphite cast iron are similar. 2) In the case of short cooling time (cooling time from Ac₁ or Ac₃ to 773 K is less than about 6s), the microstructures after heat treatment consist of high carbon martensite and retained austenite. The hardness of these microstructures at room temperature ranges from 470 to 690 HV10, and the higher the Si content of the cast iron or the higher the austenitizing temperature, the higher is the hardness. Subzero treatment after heat treatment is considered to increase the hardness of cast irons, because retained austenite transforms to martensite. 3) In the case of cooling time from Ac₁ or Ac₃ to 773 K between about 6 and 30 s, bainite, ferrite and pearlite coexist with martensite and retained austenite. The hardness decreases from about 690 HV10 to about 230 HV10 with increasing cooling time. 4) In the case of long cooling time over 60 s, the microstructures are ferrite and pearlite. The longer the cooling time, the more ferrite is produced. Hardness after heat treatment increases with an increase in the Si content of the cast iron or austenitizing temperature.
  The hardness of cast irons having large sized primary solidified proeutectoid austenite is higher than that with small sized proeutectoid austenite. The control of the solidification process is relatively important in the manufacture cast irons for heat treatments.

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  The predictions of solidification sequences and structure of high chromium cast iron were carried out by experimental and thermodynamic techniques. Experimentally determined partition coefficients of Cr and C for primary γ (k_Cr, and k_C ) resembled thermodynamic ones, though experimental k_Cr values were slightly higher than thermodynamic ones at high Cr level. The redistribution of Cr and C during the solidification of Fe-10 % Cr-1 % C alloy can be satisfactory evaluated by using the thermodynamically determined partition coefficients. Assumption of non-diffusion for Cr and complete diffusion for C in γ gives a good estimation for the distribution of these elements in primary γ as well as the amount and composition of non-equilibrium eutectic.
  The alloy contents of austenite in destabilized high chromium cast iron were also thermodynamically evaluated. The calculated values were found to be reasonably related to Ms temperatures and hardness of quenched specimens.

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  The structure of spheroidized hypo eutectic molten cast iron quenched at maximum eutectic temperature was observed at various holding times to clarify the factors which control graphite shape. The results are as follows ; 1) Graphite shape control factors were found to be ability of graphite nucleus and interfacial energy. 2) The content of magnesium does not decide the shapes of spheroidal graphite and vermicular graphite. 3) The eutectic cell growth rate is increased when the graphite shape changes from spheroidal to vermicular, type-A and type-D flake.

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  In order to clarify the effect of decarburized layer on tensile property of decarburized spheroidal graphite cast iron, rod shaped specimens with different ratios of decarburized layer were prepared by decarburization for 86.4 to 345.6 ks at 973 to 1373 K. They were tensile tested at room temperature. The shape of stress-strain curves ; i. e., the tensile property did not depend on the ratio of decarburized layer and the maximum tensile strength remained more or less constant at 455 N/mm² until the ratio reached 100 %. This suggests that voids in the decarburized layer and graphite particles in the spheroidal graphite cast iron have the same effect on the mechanical property of cast iron because of extremely weak graphite particles like the voids. After full decarburization, the maximum tensile strength was found to decrease with the increase in the excess time for decarburization. This suggests that in overdecarburization, solution-hardening effect of carbon atoms decreased due to decreasing carbon concentration in the iron. It should therefore be noted that in practical use of decarburized spheroidal graphite cast iron, overdecarburization reduces the strength of thin parts of iron.

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  Recently water mold washes are replacing alcoholic types to improve the working environment and ensure safety. A dryer is necessary for the water mold wash. In this research, far infrared rays was emitted from a radiation panel by using the heat emitted when LPG was oxidized with a platinum catalyst, and the possibility of drying the water mold wash using a far infrared rays dryer which also applies hot air emitted from the heat was examined.
  Before using the far infrared rays dryer, the using conditions of this device were set. The contribution rate to dryness decreased in order of sheets of panel, distance, ventilation, and output.
  Next, the relation of the far infrared rays dryer and the type of mold wash was clarified. It was found that the drying time differed according to the kind of mold wash and the absorption rate of far infrared rays according to the kind of mold wash. The drying efficiency was calculated from the emission rate of far infrared rays and absorption rate of each material. A high correlation was seen between the value and actual measurement value. This enable the selection of the suitable mold wash for the far infrared rays dryer.

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