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In the spheroidal graphite cast iron, the effect of Manganese was studied on the matrix and the state of graphite by differentiating the mass of samples and silicon content. The most important results were as follows; 1. Manganese greatly influenced to the pearlitization of the matrix structure of the spheroidal graphite cast iron. 2. Mass effect on the pearlite matrix was the smallest when the cementite began to precipitate. 3. Manganese did not affect the spheroidization of graphite, but it had an effect upon the fineness at low silicon content. 4. Manganese and silicon did not influence to the size of graphite in the case of ø5㎜. 5. In the case of ø25㎜ sample, by increasing the silicon content, the number of graphite was increased and the size became smaller.

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The structure and stability of the alloy system SmCo_(5-x)Cu_x with X in the range 1 to 4, have been investigated at temperatures between 600℃ and 1000℃ by X-ray diffraction techniques, electron microprobe analysis, and metallographic methods. It is shown that lattice constants of specimens annealed at 800℃ after homogenization increase with increasing the copper concentration, but do not follow the Vegard`s law. In the temperature range higher than 600℃ (but below 1,100℃), annealed specimens are unstable and a new phase having the Sm₂Co_(17) structure primarily precipitate along grain boundaries in the matrix and secondarily in the interior of grains. Electron microprobe analysis has exposed that those phases are enriched in cobalt and poor in copper as compared with the matrix. The result show that the copper element lowers the eutectoid decomposition temperature of SmCo_5 bulk alloy in great extent to near 600℃, and the sufficient heat treatment may cause the eutectoid decomposition of SmCo_(3·5)Cu_(1·5) ternary alloys. They also show that change in coercive force of SmCo_(3·5)Cu_(1·5) alloy between 600℃ and 800℃ can account for pinning interaction between domain wall movement and Co-rich precipitation particle.

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The electrode current-potential relationships of each nickel and chrome layers in various aqueous solutions have been measured, and the corrosion currents were obtained by coupling above results to investigate the mechanism of corrosion of iron or some other metal articles on which multiple layers of nickel, followed by a layer of chrome, were electroplated. The innermost dull or semibright nickel layer showed the most noble potentials at all range of current densities and in any reaction environments considered, and the next bright nickel layer showed the alternating potential with the outermost chrome layer at above conditions. Since the corrosion potential and the corrosion current in the bright nickel and chrome layers were quite small, corrosion in expected to proceed at the same time on both layer, and it would take a long time to reach upto the innermost dull or semibright nickel layer. As a result, corrosion protection of basis metals would be accomplished. The corrosion currents were comparatively small in alkaline and reducing atmospheres, whereas they were lager in acidic and oxidizing conditions.

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This study was undertaken to observe the effect of melt rate on the microstructure of ingot in the electroslag remelting process. The structural low alloy steel, SCM 4, was remelted in the 80㎜ diameter cylindrical mold at nearly definite power of 30㎾. The melt rate was varied between 288 and 434g/min by changing the electrode mold diameter ratio and the amount of slag. It was found that the secondary dendrite arm spacing was decreased as the melt rate was increased, that is, the secondary dendrite arm spacing was almost inversely proportional to the melt rate. The moan secondary dendrite arm spacing was the greatest at the ingot mid-radius part in comparing with those of the surface and center parts of ingot. It can be explained from the fact that the local solidification rate is the least at the mid-radius part of ingot. Dendritic segregation of chromium was measured by electron probe microanalyzer. No correlation between the melt rate and the microsegregation of chromium was observed. The microstructure became inferior when the molten metal pool was deepened by increasing the melt rate, whereas the higher the melt rate, the finer the microstructure. Therefore the optimum melt rate have to be determined in remelting practice for the purpose of obtaining the sound macrostructure as well as the fine microstructure.

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The heats of formation of copper-indium liquid alloys were determined by the use of a TIAN-CALVET calorimeter in the temperature range of 900-1350°K. The values of the heat capacity of formation were calculated from the temperature dependence of the heat of formation. The heat of formation was represented in terms of the mole fraction and the temperature by the polynomial emperical expression. It seems to be possible to explicate the thermodynamic behavior of this system with the terms of the existance of a cluster Cu₃In and the positive contribution of the heat capacity.

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Procedures were developed in the X-ray method for routine measurement of preferred orientation for chemically vapor deposited tungsten tubes. The interpretation of the experiment data is based on the inverse pole figure technique. Preferred orientation measurements indicated that the grains in the circumferential, longitudinal, outside, and inside sections contain mainly{100} planes and that the fiber axis of the tube is <100>. This method is very rapid and is generally best suited to the problems involved with fabricated shapes, such as tubes.

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An attempt was made to explain the effect of prestrain on strain aging in low carbon steel. Carbon steel bar was normalized at 900℃ in order to eliminate the segregation of solute atoms such as C and N and to release the residual stress, and then prestrained in the range of 0% to 14% followed by aging at 200℃ and 400℃. The effect of prestrain on creep strength was also discussed. Yield strength was increased with increasing the prestrain, and the aging was accelerated noticeably with the degree of prestrain by the increase of aging temperature. The work hardening exponent was decreased as the prestrain increases. Creep strength was also increased with increasing the prestrain.

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