Surface hardening treatment by laser beam was applied to austempered spheroidal graphite cast iron (ADI) bar specimens 30 mm in diameter, and wear characteristics in dry slip-rolling contact conditions were investigated based on the irradiating conditions of the laser. When laser beam was irradiated on the surface of the ADI bar, remelting and the corresponding rapid cooling took place, and the remelted zone (RZ) resulted in the formation of a mixture of retained austenite and eutectic carbide structure of which Vickers hardness was about 600 HV. The microstructure of the heat affected zone (HAZ) formed around the RZ transformed into martensite with high hardness (850-950 HV) from the ausferrite of the as-austempered structure of about 600 HV. But when the number of laser irradiations on the bar exceeded 90, the irradiation spacing became so narrow that the neighboring HAZ overlapped with each other, resulting in decreased HAZ hardness to about 600 HV because the HAZ transformed into tempered-martensite by tempering. While the number of laser irradiations increased up to 120 on the bar, wear loss decreased remarkably. However, when the number of irradiations exceeded 120 on the bar, wear loss increased with increasing number of irradiations. The wear loss of ADI was minimum when the number of irradiations was 120, and decreased to 60% of ADI without irradiation. The surface hardening treatment by laser irradiation is concluded to be very effective for improving the anti-wear characteristics of ADI, and its wear characteristics are found to be influenced largely by the area rate of RZ and HAZ on the surface.

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  CaO-MgO refractories have been used as the main refractory for converters in steel making. Recently MgO-C refractories are increasingly being used instead of CaO-MgO refractories due to their durability.
  While the improvement of properties of CaO-MgO refractories, especially durability, is still attempted and reported, very few studies on the refining properties of CaO-MgO have been reported except for molten iron with high oxygen content which has superior desulphurization properties over CaO.
  When considering applications to the ladle furnace for clean steel making, it is important to study the refining properties of CaO-MgO refectories in molten iron with low oxygen content.
  Experiments were conducted to study the refining properties of CaO-MgO in molten iron with low oxygen content, and the results showed that CaO-MgO refractories have outstanding desulphurization and repetition properties when Al is added to molten iron with low oxygen content.

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  A system to accumulate technical information on casting defects was developed using a relational database method. This system enables effective use of various technical information from casting workshops which are the key to improving casting technology. We also developed a system to share information on casting technology over the Internet. Consequently, with no restriction of time and space, this system realizes information sharing on casting defects and provides the venue for virtual discussion among engineers.

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  Flake graphite cast iron containing aluminum is known as a material having excellent heat-resistance. In this research, the characteristics of the surface modification process and the wear property of surface modified aluminum alloyed cast iron were investigated.
  When flake graphite cast iron containing 6 mass% aluminum was heat-treated at 1273 K in air, alumina precipitated at the positions where graphite existed, showing the same shape of flake graphite. The thickness of alumina dispersed layer reached about 1 mm by heat-treating for more than 72 ks at 1273 K. This material was evaluated by the pin-on-disk method, showing that it has excellent wear property compared to normal flake graphite cast iron. Surface modified layer showed excellent wear-resistance especially at a test speed of 1.0 m/s. Also, at a test speed of 0.1∼0.5 m/s, this layer showed wear resistance better than normal cast iron. Apparently the material surface transforms into an oxidized wear state due to the adhesion of oxides including alumina, resulting in improved of wear resistance.
  This is a new surface modification method applying decarburization of graphite and the easy oxidation feature of aluminum. This method is easy using only heat-treatment in air, and provides a possibility for cast iron to create new characteristics by substituting other substances for the graphite included.

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  Nickel aluminide based intermetallic compounds as a surface layer on spheroidal graphite cast iron substrate (FCD 450) were combustion synthesized from a powder mixture of elemental Ni, Al and Si powders. With a composition of Ni-78 at% (Al-8 at% Si), Al₃Ni and Al₆Ni₃Si were formed mainly by hot pressing. Densification of the compact was enhanced with increasing the eutectic Al-Si ratio in the precursor powders. Al-Si eutectic liquid phase infiltrated well into the boundary of each particle, which also reacted with the substrate to form intermetallic reaction layers. These layers were formed on both sides of the coating layer and FCD substrate, and the constituent phases were identified as Al₇Fe₂Si, FeAl₃ respectively. The interface of reaction layers of 10 μm were chemically well-bonded.

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