The influences of alloy elements on the rolling contact fatigue limit (F^∗) were examined for the Fe-2.2 % C-6 % V-5 % Cr-5 % Mo-0/5 % W-0/5 % Co alloys by the Nishihara type wear test machine using light oil lubricant. The cast alloy specimens were heated at 1273K for 3.6ks and then tempered twice at 823K for 3.6ks. F^∗ of W free Fe-2.2 % C-6 % V-5 % Cr-5 % Mo-5 % Co alloy showed the highest value, suggesting that plate-like M₂C type carbides decreased F^∗. F^∗ of these specimens were much higher than that of high chromium cast iron with coarse M₇C₃. Though the addition of 6 % Ni and 3.4 % Si to this high speed steel type alloy resulted in the precipitation of a small amount of graphite flakes and lower hardness, F^∗ was still kept at a higher level.

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  Aluminum alloy castings for automobiles are partially strengthened by remelting their surfaces to a depth of several mm with a TIG welding machine. In the present work, a method was studied to evaluate the thickness and the width of the remelted zone nondestructively, by applying a phenomenon that the intensity of back scattering of ultrasonic wave depends on the size and distribution of the crystal grain in materials. By applying this method, the thickness and width of the remelted zone were evaluated for a plate made of Al-Cu-Si alloy castings with a thickness of about 18 mm nondestructively. They were in good agreement with the thickness and width of the remelted zone obtained by destructive testing : sectioning, etching and measurement of specimens.

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  Photofabrication is a rapid prototyping process that produces patterns easily and quickly. Patterns are composed of multilayer photopolymer cured by laser or ultra violet ray. As laser devices are expensive, they have not been widely adopted. The exposure device in this paper used a mercury xenon lamp with an ultraviolet rays irradiated through optical fibers. 200 and 400 μm fibers were used for the exposure device, but it was found that the 200 μm fibers were superior to 400 μm fibers for laminated patterns. Three kinds of photopolymer were used for the investigation. These are urethane (M30), an urethane and unsaturated polyester mixture (FP50), and an unsaturated polyester (G42). Cured resin patterns in plaster molds were heated at 873K × 10.8ks. The heated resin patterns disappered and small amount of ash was observed. AC4C aluminum alloy were poured into these molds by centrifugal casting. No cracks were observed in the molds with FP50 and M30 patterns, and fine castings were obtained. Molds with G42 patterns generated cracks due to thermal expansion of the pattern and surface of AC4C castings inferior good compared with the castings of the FP50 and M30 patterns.

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  Recently, one of the authors has developed the thermomechanical treatment (TMT) method for ductile cast iron. In this study, the effects of austempering temperature and graphite size on the toughness of thermomechanically treated ADI were investigated. Austempering transformation is accelerated due to rolling and an increase in the reduction ratio. Rolling at the austenitizing temperature mostly diminishes γ-pool around eutectic cell boundary and generates homogeneous microstructures. The toughness increases with increasing reduction ratio and austempering temperature. The maximum absorbed energy is 46 % higher than ordinary ADI without decrease in hardness. Rolling at both the austenitizing and austempering temperatures completely eliminates γ-pool and shows finer microstructures than the ADI rolled at austenitizing temperature. The toughness and hardness increase with reduction ratio. The maximum absorbed energy and hardness are 27 % and 23 % higher than ordinary ADI, respectively. The toughness of ADI depends mainly on the extent of γ-pool and not on graphite size.

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