The X-ray diffraction line profile analysis technique has been applied to the study of fatigue damage below the surface of the work and the backup rolls of a cold strip mill, and the backup rolls of a hot strip mill. Half value breadth has been taken as a measure of fatiguing.
The fatigued zone below the surface of the rolls correlated well with the half contact length, L, being 0.03L in the work roll of cold strip mill and 0.1L in the other rolls. Changes in the half value breadth with an increase in the number of cycles of roll contact differ according to the surface hardness of the roll: continued cycling results in a decrease in the half value breadth at the surface in hard rolls (Hs≥60), and an increase in soft rolls (Hs≤50). This technique, the X-ray study of fatigue, can be extended to the prediction and prevention of accidental failure of rolls due to fatigue fracture such as spalling. Furthermore, the amount of surface dressing at regular maintenance of rolls can be saved significantly on the basis of an accurate evaluation of the depth of the fatigue damaged zone.

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The processes of cementite dissolution, recrystallization and annealing-texture formation during isothermal annealing have been observed in cold-rolled sheets of a low-carbon aluminium-killed steel in which the effect of the pre-precipitation clusters of aluminium-nitride was eliminated by preliminary heat-treatments. Inhibition of nucleation due to pinning of dislocations by dissolved carbon atoms and inhibition of the growth of recrystallized grains by carbon atoms or by fine cementite particles have been considered as probable effects which decrease the rate of recrystallization. The predictions were, however, found to be inconsistent with the experimental results obtained. It was supposed that different annealing textures were produced through changes in the size and distribution of constrained-deformation regions in the deformed iron matrix. When the cementite particles were coarse and widely spaced, an annealing texture with strong {222} and weak {110} orientations was obtained by rapid heating directly to a high temperature. In a case when the hot band contained fine spheroidal cementite particles, a similar annealing texture could be obtained by two-stage annealing. The presence of pearlite had a deteriorating effect on the development of the favourable texture.

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Effects of electromagnetic stirring on the solidification structure of continuously cast SUS430 slabs were investigated to reduce the ridging of cold-rolled sheets by grain refinement of the solidification structure. The following results were obtained:
(1) The area in which equiaxed crystals form increases with increasing stirring intensity and decreasing superheat (ΔT) of molten steel. The most suitable stirring mode is the alternate stirring. The effect of ΔT can be moderated by lowering the position of the stirrer, but the ratio of equiaxed crystals decreases in this case. Appropriate conditions for obtaining a ratio of equiaxed crystals over 60% were determined.
(2) Ridging is reduced as the ratio of equiaxed crystals increases. Stable ridging obtained for 50% or more equiaxed crystals is the same as that of steel sheets rolled from ingots.

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The intention of the paper was to improve the mechanical properties of ductile cast iron by a duplex matrix which is used in steels.
Ferritic ductile cast iron was heat-treated to produce the following duplex matrices of various proportions; ferrite-bainite, ferrite pearlite and ferrite-tempered troostite.
The tensile and impact tests were performed on the irons with a duplex matrix. The 0.2% proof stress, tensile strength and hardness increase with increasing volume fraction of the second phase, but there is no linear relationship known as the law of mixture. The harder the second phase is, the higher the strength becomes. In the elongation and impact energy of the alloy with higher silicon content, two peaks appear at volume fractions of upper bainite of about 50 and 95%, and the transition temperatures drop to minimums; the elongation values are 18 and 12%, the absorbed and upper shelf energies are 14.5 to 15kg•m/cm² and the transition temperatures are -45° to-47°C in the un-notched specimen.
Thus, the strength and toughness of ductile iron can be improved by the proper second phase of a proper volume fraction in ferritic structure. The improvement comes from the fine duplex matrix structure and low carbon content of the second phase, which is a characteristic in the austenitizing of ferritic ductile cast iron, and it also comes from the second phase with high strength and high ductility, such as upper bainite, formed mainly around the graphite nodules, probably because of preventing a crack initiation at the graphite-second phase interface.

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The effects of microstructures and molybdenum alloying on low temperature toughness have been studied in carbon free 11Ni-O-4Mo steels reheated below Af temperature after double normalizing. In spite of very low content of C, N, P, S and other impurities in these steels, temper embrittlement appeared in reheating or slow cooling in the range of 450° to 525°C. To inhibit this embrittlement the following two methods were shown to be effective. One was using the substructure which had a small amount of fresh martensite and the other was alloying one percent molybdenum. There was the optimum molybdenum content, since at higher contents age-hardening and solution hardening by this element became the inevitable cause of the low temperature brittleness. Further, it was concluded that the 1Mo steel having a small amount of fresh martensite showed excellent properties in both strength at room temperature and toughness at -196°C. This steel had also a good toughness at about -250°C.

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Mineralogical study of LD converter slag was carried out by means of microscopic and EPMA examinations and phosphorus was found to exist only in dicalcium silicate as solid solution. This led to the study of separation of dicalcium silicate from LD converter slag in order to remove phosphorus.
When liquid slag was solidified slowly, most dicalcium silicate particles accumulated in the top part of the crucible and fewer in the bottom. The phenomena can be interpreted as follows; on solidification, dicalcium silicate is crystallized primarily and floats up owing to the difference of density between dicalcium silicate and residual liquid. By using this phenomena, we can separate LD converter slag into two layers, top and bottom in a vessel. As a result of slow cooling, CaO, SiO₂ and P₂O₅ are enriched in the top, and FeO, Fe₂O₃ and MnO in the bottom.
Dicalcium silicate is apt to separate more efficiently with higher total iron content in slag, and at higher start temperature of cooling, close to liquidus temperature. The efficiency of separation was improved by blowing oxygen into the molten slag before cooling.

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