Carefully controlled granulation experiments were carried out on a haematite ore with a wide size distribution (0-8mm) over a range of moisture contents. At any one moisture content, the finest size fractions could be classified solely as layering particles whilst the largest size fractions acted only as nuclei particles. Between these two extremes, a proportion of particles in any one size fraction behaved as nuclei particles, the remainder being layering particles. Hence each particle size fraction could he characterised by a partition coefficient. The partitioning of an individual size range between nuclei and adhering particles was shown to be dependent on the moisture content. For each moisture content, the partition curve could be modelled using a log-normal function. The variation of adhering layer mass with granule size was investigated and it was found that adhering layer thickness was approximately proportional to nuclei diameter at lower moisture contents. At higher moisture contents there was an optimum nuclei particle size for which the ratio of granule mass to total nuclei mass was a maximum.
A population balance model to predict granule size distribution was developed and tested against experimental data. The important model parameters were those describing the particle partition curve. Excellent agreement was found between experimental and model predicted granule size distributions for the full range of moisture contents covered.

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Solute redistribution during solidification has been analyzed by a profile method which has approximately considered the two-dimensional diffusion in solid phase. Derived equations have been compared with conventional equations, numerical analyses and experimental data. It was found that a newly derived simple equation can estimate the liquid concentration better than Brody-Flemings' equation but numerical calculation or further improvement of the analytical treatment is required for estimating the segregation ratio correctly. 7n addition, calculations showed that the dendrite shape, growth mode (parabolic and constant growth) and diffusion in the liquid phase did not affect so much the solute redistribution at least for fS<0.9. The diffusion path, which is thought to be a more important factor, has also been discussed and an equation is proposed for the case where diffusion path or the partition coefficient changes stepwise.

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In order to elucidate the wear mechanism of ZrO₂-graphite refractories used around the powder line of submerged nozzles, the authors carried out erosion tests with the variety of mold powders using an induction furnace. The mold powders with low viscosity or high [F^-] content were found to wear away ZrO₂-graphite refractories heavily. The erosion behavior of ZrO₂-graphite refractories can well be explained by the basicity of a mold powder which consists of ion-oxygen attraction parameters of the chemical compositions in the mold powder. Observing the microstructures of the samples after test, it is clarified that the penetration of low-viscosity components in the mold powder disintegrate carbon bonding and also granulate ZrO₂ grains into fine particles, consequently the erosion of ZrO₂-graphite refractories is aggravated.

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High-carbon steel wire rods with a composition of 0.85wt% C, 1.19 wt% Si and 1.19wt% Mn were given a lead patenting treatment. The result shows that the steel wire rod has a tensile strength higher than that of plain high-carbon steel rod by 17kgf/mm2. Then, the wire rod was drawn by the direct cooling drawing system to prevent strain aging. Based on these experimental results, high-strength large diameter galvanized steel wires with nominal diameters of 5, 6, and 7mm were trially manufactured.
The mechanical properties of the new Si-Mn galvanized steel wires were experimentally proved to be 20 to 30kgf/mm2 higher in tensile strength and 7 to 10kgf/mm2 higher in fatigue strength than plain high- carbon galvanized steel wires. There was no perceivable deterioration in toughness, and the relaxation value after 10h was only one-third of that of the high-carbon galvanized steel wires. Thus, the newly-developed high-strength Si-Mn galvanized steel wires were proved to be suitable for use as cable wires for long span suspension bridges and other purposes.

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Computer simulation of serration, that is, serrated plastic flow observed generally in almost all metallic materials at very low temperatures has been investigated by comparing with the actual deformation behavior of Fe-Ni binary austenitic steels in some coolants such as liquid helium. The simulation was carried out by dividing the specimen into small elements and calculating repeatedly basic equations for thermally activated movement of dislocations and for thermal balance to obtain the amount of strain and the temperature change of each element during a small time increment. The thermal balance was considered among the heats converted from the mechanical work, conducted a specimen and exchanged with the coolant. Although details of the dislocations movement has remained unclarified at cryogenic temperatures, it was concluded that the characteristics of the serration and the accompanied phenomena could be simulated very well without unreasonable assumptions. The effects of some factors on the serration were discussed by using the simulation.

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Effects of carbon on creep-rupture properties and room temperature toughness of high (9-10)Cr-(1.8-2)Mo ferritic heat resisting steels containing V and Nb were studied. The carbon content was varied from 0.02 to 0.23% in order to improve toughness without decreasing the creep-rupture strength. Difference existing in creep-rupture strength and in Charpy absorbed energy between 10Cr-2Mo steels and 9Cr-1.8Mo steels were studied with respect to the ratio of delta ferrite to martensite, the precipitates, and the microstructure.
The results indicated that the 9Cr-1.8Mo-0.1V-0.05Nb steels with 0.14% C tempered at 800°C showed good toughness, and that 10⁴h rupture-strength of the steel was as high as that of SUS 316 austenitic stainless steel at 550°C and SUS 304 at 600°C. It was concluded that the optimum amount of delta ferrite from the point of view of creep-rupture strength and Charpy absorbed energy was 10-20%.

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