Multi-component white cast iron contains basically 5 mass% of Cr, Mo, W, V, each and 2 mass% of C and Co. The effect of Cr content in the cast iron on continuous cooling transformation behavior was investigated by varying Cr content from 1 mass% to 9 mass%. The austenitizing temperatures used in this experiment were 1273K and 1373K.
  For up to 5 mass% Cr, the critical cooling rates of pearlite transformation (V_C-P) were 0.15 K/s at 1273K and 0.08 K/s at 1373K austenitization. As Cr content was increased to more than 5 mass%, however, both the V_C-P decreasd gradually, and at 9 mass% Cr, they were 0.055K/s and 0.029K/s, respectively.
  The critical cooling rate of bainite transformation (V_C-B) decreased continuously with an increase in Cr content. The relations can be expressed by the following equations;
      1273K austenitization : V_C-B = 5.1 e^-0.4⋅%Cr
      1373K austenitization : V_C-B = 5.0 e^-0.5⋅%Cr
  Regardless of the austenitizing temperature, the Ms temperature decreased as the Cr content rose to 5 mass%, increasing to over 5 mass% Cr. Mf temperature was seen in irons containing more than 5 mass% Cr and in the case of 1273K austenitization, and it rose with an increase in Cr content. The maximum macro-hardness of transformed specimen decreased uniformly as Cr content increased.

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  Recently, as the performance of automobile engine improves, there are more pressing needs for stronger thermal resistance to cast aluminum alloys applied to engine parts. In this study, thermo-mechanical fatigue test was conducted using strontium modified AC4CH-T6 alloys. In order to study the effects of modification on mechanical properties, tensile test and instrumented Charpy impact test were carried out. The mechanical properties and thermomechanical fatigue life of AC4CH alloy improved with the addition of strontium, refining and spheroidizing eutectic Si particles. This resulted in the suppression of continuous crack propagation in the material. The results showed that the thermomechanical fatigue life is improved by the decrease of plastic strain and increase of tensile ductility.

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  Alumina short fiber preforms with Al₂O₃ binder were fabricated and infiltrated with AZ91D magnesium alloy melt by squeeze casting. The effects of fiber volume fraction, temperature, and heat treatment on the tensile strength of the composites were investigated. The fiber volume fraction ranged from 0 to 33%. Aging time to peak hardness was shortened as the fiber volume fraction increased. The Al₂O₃ binder provided a satisfactory interfacial bond between the fiber and the matrix without interfacial reaction or fiber damage. The tensile strength of the composite increased along with the fiber volume fraction at 293 K. The as-cast composite showed high strength with the fiber volume fraction of 18% at 523 K. Examination of fracture surfaces and calculation of the tensile strength using the rule of mixture indicated that the 18% fiber reinforced as-cast composite had a strong interfacial bond even at high temperatures.

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  In order to clarify influences of moisture in air on the fatigue crack propagation, fatigue crack propagation test was carried out for three kinds of spheroidal graphite cast iron (As-cast, QT, ADI) in room air and dry air. The obtained results were as follows;
(1) In room air, ΔK_th in three kinds of material were higher than that in dry air. One of the reason, oxides were difficult to be produced on fracture surface in dry air, the oxide induced crack closure effect was difficult to be generated.
(2)In low ΔK, da/dN in dry air was higher than that in room air of three materials. It was due to the crack closure effect. But ADI was affected by other factors.
(3)In high ΔK, da/dN in dry air was lower than that in room air of QT and ADI. It was due to the acceleration factor caused by moisture in air.

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  The deformation of EPS pattern in the vibration flask for the evaporative pattern casting process was investigated experimentally. The strains of plate-type and duct-type EPS patterns were measured by a strain gauge bonded to the EPS pattern. For the uncoated plate EPS pattern, when the steel shot was packed, the strain of EPS pattern was slightly greater than when silica sand was packed. By coating with suitable thickness, the strain of EPS pattern decreased considerably and the effects of the packing material and direction of EPS pattern on the strain were not significant. And it was found that the strain of duct-type EPS pattern placed horizontally at the packing process decreased with the vibration of the flask at suitable vibration frequency. This effect of the relaxation of the strain became remarkably increased as the fluidity of the packing in the vibration flask increased.

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  Because thin mold cores that are less than 5mm thick made by the cold box process are liable to break in molding and casting and this damage affects the dimension of castings considerably, it is a serious problem in thin wall casting. A new type of mold wash has been developed to provide increased break strength in thin mold cores. It was found that sodium aluminates mold wash are resistant to core breaking, penetration, sand burning and occurring gas defects such as blowholes and pinholes as compared to conventional mold washes. It was confirmed that a penetrated layer of about 1mm thick near the surface of the mold core increases break resistance of the core mold by two to three times according to dipping times of mold wash.

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