The surface breakage rate constant for three Australian battery cokes was measured in a specially modified tumble drum using a previously developed technique. The effect of experimental test parameters-coke size, sample mass, drum speed, lifter height and lifter number-on the surface breakage rate constant was examined. The motion of coke particles within a tumble drum was filmed in a simulation experiment with a 0.31m diameter drum. Particles were raised on the lifters, fell and collided with the bottom of the drum. These collisions were the main source of fines (minus 1mm) production rather than true abrasion as depicted by a rubbing, rolling action. Hence the term surface 'breakage' is more appropriate than 'abrasion' to describe the breakage process. By measuring the volume of coke carried by each lifter and the height of fall of the coke, the effect of drum speed, sample mass, lifter height and number on the rate of surface breakage was successfully explained. The surface breakage rate constant was found to be proportional to particle size to the power 0.33 for the three cokes studied. A normalized surface breakage rate constant was derived which allowed comparison of cokes with different size distributions. This parameter characterises the coke surface breakage resistance.

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A hematite sphere of 3.3cm diameter was reduced in an atmosphere of hydrogen with the pressure up to 2.7MPa at 1173K. The experimental results were analyzed by the three interface unreacted-core shrinking model with dynamic effective diffusivity. Effect of gas flow through the product layers on the overall reduction rates was reasonably elucidated by the use of the structural constants obtained from the permeability and the isobaric diffusion tests.
The effect of pressure on the reduction rate was found to be essentially determined by four rate parameters: the effective molecular diffusivity and the mass transfer coefficient at 0.1MPa, (D°_AB)_eff and k°_mA, and Knudsen diffusivity k_A and the chemical reaction rate constant k_S. When (D°_AB)_eff or k°_mA increases at constant k_S and KA, both the reduction rate and the pressure effect increases. When k_s or k_A increases at constant (D°_AB)_eff or k°_mA the reduction rate increases but the pressure effect decreases. The reduction rate increases with increasing pressure, while it shows the maximum when the molecular diffusion through the product layers reaches a ratedetermining stage. The stagnation phenomenon of the pressure effect appears when the contribution of the molecular diffusion increases.

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Studies on powder injection method and its metallurgical effects on hot metal pretreatment were carried out.
To avoid the nozzle clogging, smooth powder transport from powder dispensor to nozzle is an important factor for powder injection practice and linear gas velocity higher than 330m/s is necessary for gas stirring practice.
The effective desiliconization and dephosphorization in hot metal can be obtained by injection method. Static pressure available in injection method, together with increasing interfacial area, increasing transitory reactions and preventing fume loss, accelerates desiliconization or dephosphorization in hot metal.

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A mathematical statement is developed describing the three-dimensional magnetic field and electromagnetic force field induced in a slab or in a billet, through the application of stirring coils in a continuous casting process. These problems are necessarily three-dimensional because of the inherent features of the system geometry, although two-dimensional simplifications are of course possible.
The resultant equations are solved numerically, and results are presented for both a slab with a linear stirrer and a billet with a rotary stirrer. The computed results have shown that within the vertical sections covered by the inductor the electromagnetic force fields obtained were very close to values that would have been obtainable through a two-dimensional approximation. However, on approaching the vertical position corresponding to the outer edge of the inductor, the electromagnetic force field vector decayed quite rapidly and additional force field components appeared. This behavior could not have been predicted on the basis of a two-dimensional analysis.

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In isothermal forging, since the die is heated as well as the workpiece, high-temperature strength is essentially required for the die material. In particular, isothermal forging of superalloys is carried out at high temperature ranging 1000-1100°C, thus a molybdenum-base alloy, TZM, is generally used as a die material. Although TZM has good high-temperature strength, its oxidation resistance is very poor at above 600°C, therefore, forging must be done in vacuum or inert-gas atmosphere.
If there is a die material having both enough strength and oxidation resistance at around 1000-1100°C, isothermal forging of superalloys in air will be possible, and the forging apparatus will be simpler.
To develop such a die material, the authors directed their attention to chromium free nickel-base cast alloys, because such alloys are able to contain a large amount of heavy metals such as molybdenum and tungsten, as being soluble in γ and γ' instead of chromium, and are expected to have higher strength at above 1000°C.
Several conventional and experimental alloys were investigated. From the results of compression, compressive creep and oxidation resistance tests, “Nimowal” (Ni-10Mo-12W-6Al-0.01Y) showed the best properties as a whole. Its short-time strength is equivalent to that of Mar-M200 at 950-1000°C, higher than that of Mar-M200 and equivalent to that of TZM at 1050-1100°C. Its compressive creep strength is higher than that of Mar-M200 at 1000-1100°C. Oxidation resistance of Nimowal is equivalent to that of Mar-M200 and enough to be used in air. Moreover, JVimowal has better machinability than Mar-M200.
Simulation tests of isothermal forging of superalloys in air were made with Nimowal being used as the die material. One-tenth model disk of In-100 was successfully forged from the extruded billet without any damage or significant oxidation of the die.

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The behavior of the hot rolled wire rods during cooling in water was precisely investigated by a laboratory test and it has been made clear that cooling by subcool-boiling in a gaswater mixed fluid can be a new cooling method and this fluid can be taken as a new coolant which has excellent characteristics for patenting.
The new direct heat treatment system having the very wide range of cooling speeds, in which this new cooling method and new coolant was applied as the principal technology, was developed.
The treated wire rods have not only the good mechanical properties but also the high uniformity within a coil.

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Microstructures of hot work tool steels, AISI H13, HIO, and H19 tempered after quenching at various cooling rates are studied for improvements of the toughness of these steels. It is found that the development of upper bainite with decreasing rate of quenching is accompanied by the following microstructural changes.
1) Increase in the width and length of bainite grains and the effective grain size
2) Preferential precipitation of carbides along prior austenitegrain boundaries
3) Dispersion of fine carbides in matrix
These microstructural changes lead to reduction of the toughness in all the steels; deterioration occurs in H10 and H19 at a higher cooling rate than in H13. The toughness value reduces in the order of H13, H10, and H19, in good correlation with increasing order of the density of frne carbides in matrix and the fraction of retained carbides.

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