CO₂ laser beam was applied to the cladding of chromium alloy using a beam scanner. The hardness and microstructure of the clad layer were investigated by changing the laser power, number of clad layers and overlapped width of the laser beam. The average hardness of the clad layer obtained was 550∼600 HV 0.1, when the conditions were; laser power of 2500 W to 2900 W, clad number of one layer to two layers (thickness of clad layer ; 0.85∼1.90 mm), overlapped width of 0.5 mm, cladding speed of 400 mm/min, defocusing distance of 30 mm, oscillated width of 7 mm and argon as the shielding gas. The microstructure of clad layer was completely transformed into a fine dendritic structure (secondary dendrite arm spacing ; 3∼5 μm) and eutectic structure by the rapid solidification conditions. A heat affected zone was produced on the surface of the carbon steel (base metal) and a martensitic structure could be observed. The heat affected zone was then heat treated also with CO₂ laser beam. The martensitic structure (700 HV 0.1) of the heat affected zone transformed into troostite. EPMA line analysis indicated that an alloyed layer (thickness ; 20∼30 μm) exists between the clad layer and base metal. These results show that CO₂ laser beam cladding of chromium-based alloy serves as a new surface treatment process for carbon steel.

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  Cu-Sn-Zn alloys with different solute content were cast, and the spectroscopic surface reflectance of the alloys was analyzed. The principal component analysis was carried out with spectra at wavelength ranging from 450 nm to 650 nm to obtain a sub-space composed of 7 eigen vectors. The solute content of the alloy estimated with the sub-space was in good agreement with the nominal composition. At higher solute content, the estimated value varied considerably. The analysis with focussed light beam confirmed that the macrosegregation in the specimen caused variation of data at higher solute contents.

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  The influence of sulfur addition on the toughness of ferritic 16 mass % Cr cast steels was investigated in relation with sulfide distribution. Three types of base alloys different in solidification reaction were used and were added with up to 0.2 mass % sulfur. Although Charpy impact toughness at room temperature and transition temperature are slightly affected by sulfur addition, the intermediate temperature toughness (ITT) above the transition temperature decreases with increasing sulfur content, and degree of decrease differs among the base alloys. In the base alloy with 0.04 % C, which solidifies in α single phase, ITT is remarkably decreases by the addition of up to 0.1 mass % sulfur, because fine sulfides crystallize on the grain boundaries, resulting in embrittlement of those areas. In the base alloy with 0.2 % C and 0.7 % Nb, in which Nb carbides crystallize, ITT is also sharply reduced, because sulfides crystallize in the interdendritic regions together with Nb carbides, also resulting in embrittlement of those areas. On the other hand, in the base alloy with 0.2 % C, which solidifies through peritectic reaction (α + liquid → γ), the decrease in ITT with increasing sulfur content is small. Its ITT is highest amongst all base alloys even when the sulfur content is over 0.1 %, because large sulfides crystallize uniformly.

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  Composition is the most important element in controlling green sand. Oolitics, one of the composition, is quantified by analyzing quartz by the silica program test. However this test takes more than 8 hours and the analyzer needs to spend one hour on this work. To shorten this time, we examined another method to quantify oolitics by using X-ray diffractometric analysis for quartz. We chose the calibration curve method as a quantitative. First, we changed the quartz content by using quartz and feldspar, then measured the diffraction X-ray intensity, and obtained calibration curve between quartz content and diffraction X-ray intensity. As a result of comparing each diffraction X-ray intensity of the first peak (angle of diffraction is 2 θ 26.6°) and the second peak (2 θ 20.9°) with quartz quantity analyzed from the silica program, the quantitative precision from the second peak was found to be better, because there was no other material peaked around 2 θ 20.9° for green sand. Although it takes almost 6 hours to analyze quartz by X-ray diffractometric analysis, the actual working time for the analyzer was shortened less than 30 minutes, and the efficiency improved more than two times compared with the silica program test.

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  Continuous cooling transformation behavior of Fe-5 % Cr-5 % Mo-5 % W-5 % V-2 % Co alloys with 2.0 and 2.8 % C (mass %) was investigated at two austenitizing temperatures, 1273 K and 1373 K. In spite of the difference in carbon content and austenitizing temperature, pearlite and bainite transformations were found to separate to the top and bottom individually. Regardless of the austenitizing temperature, the bainite nose was located at the short time side than the pearlite nose in low carbon cast iron. In the high carbon cast iron austenitized at 1273 K, the pearlite and bainite nose times were more or less the same, but a delay was seen in the bainite nose time in iron austenitized at 1373 K. Irrespective of the austenitizing temperature, the temperatures of pearlite and bainite noses and bainite nose time were similar in both irons. However, the time of pearlite nose in low carbon cast iron was located at the long time side compared with high carbon cast iron. The Ms temperatures appeared from 340 K to 495 K but the Mf temperatures were below room temperature. The Ms temperatures were found to be higher in the low carbon cast iron and lower in both irons austenitized at 1373 K.

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  This paper introduces a new process called “Casting-RIM”, which utilizes casting technology, for the new resin Poly-Dicyclo-Pentadien (PDCPD). The process was developed jointly by Ebara Corporation and Nippon Zeon Co. Ltd. PDCPD, composed of carbon and hydrogen, is an olefin resin. Its quasi cubical molecular structure gives it excellent properties as a material. Succesful application of the Casting-RIM process for forming large, thick parts from PDCPD has led to its increasing use for machine parts such as parts for pumps.

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