The effect of K₂O, Na₂O and CaO on the reduction behavior of Fe₂O₃ was investigated. Platelets of Fe₂O₃ single crystals were prepared by the flux method. The size of the crystals was approx. 3mm in width and 0.3mm in thickness. For the reaction of Fe₂O₃ with K₂O, Na₂O, and CaO, small amounts of each carbonate powder were placed on the flat plane (0001) of Fe₂O₃ and heated at 1100-1300°C in the air. It was confirmed by EPMA that the reaction products with those substances were formed on some parts of the Fe₂O₃ crystal. The crystals were reduced at 750°C in CO and H₂ streams, and the surface structures were observed by SEM.
The results obtained were as follows. When alkaline metals (as Na₂O, K₂O) were present in Fe₂O₃, the abnormal swelling took place during the reduction. It was considered that the swelling was caused by (1) the cracking of the crystal at the early stage of the reduction, (2) the fibrous iron formation and (3) the carbon deposition on the reduced iron. The fibrous iron formation was also observed in the grain boundary of calcium ferrite. The reduction with a glassy slag (SiO₂-Al₂O₂-CaO) was also investigated and no swelling phenomenon was shown.

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Investigations have been carried out to determine the effect of structure viz., martensite, bainites and ferrite-carbide aggregates on the tensile and tear properties as well as the nature of fracture in a 0.11%C-1.5%Mn-1.04%Cr-0.25%Mo-0.003%B steel. Both total elongation and uniform elongation vary almost linearly with tensile strength, the ratios of uniform elongation to total elongation being confined to 0.6-0.7. Replacing total elongation by uniform elongation to characterize the high strength-ductility combination is not found to be identical. The toughness (as measured by unit propagation energy) follows a trend almost similar to that of TS×El. Shear and/or microvoid coalescence are the operating modes of fracture and these, in turn, depend on the steel toughness and structure.

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This paper reports about the evaluation of the service life of a galvanized steel sheet coated with thermosetting silicone polyester resin and intended for an exterior building material. The contents are as follows:
(1)A composite cycle test is the best method as an accelerated weathering test because it gives a largest acceleration rate to deterioration and reveals the similar deteriorated condition to the outdoor weathering test.
(2) A complex deterioration of the resin proceeds in the film surface layer, with the thickening of remaining silicon dioxide being observed in particular.
(3) Complex deterioration factors affect the properties of the material.
(4) Appearance change, physical change and decrease in adhesion strength between film and steel sheet are caused by the chemical change of the film.
(5) The silicone polyester resin coated galvanized steel sheet has a high abrasion and corrosion resistance.

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This paper report about the evaluation of the service life of a galvanized steel sheet coated with thermoplastic polyvinyl chloride resin and intended for an exterior building material. It can be summarized as follows:
(1) A dew cycle weathering test is the best method as an accelerated weathering test because it gives a high acceleration to deterioration and reveals the similar deteriorated condition to outdoor weathering testing.
(2) It can be safely said that the polyvinyl chloride resin is oxidized and the double bond is formed because of the dechloridization of the polyvinyl chloride resin in the film surface layer.
(3) Of all the deterioration factors, ultraviolet rays and heat are most significant.
(4) Appearance change, physical change, and decrease in adhesion strength between film and steel sheet are caused by the chemical change of the resin.
(5) Although the film surface of polyvinyl chloride resin on a galvanized steel sheet deteriorates, the bulk material does not deteriorate. Accordingly, the evidence accounts for the high corrosion resistance of the film.

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To know the effect of injecting powder with gas on the bubbling-jetting transition, an experimental study has been made on powder injection into a liquid. The gas powder mixture was injected into a water bath through a nozzle of 0.2cm in I.D. installed at the vessel bottom. The powders used were glass beads of 105-149μm, 177-210μm, and 350-420 μm. The mixture jet behavior was photographed by a high speed cinecamera. The injecting pressure was measured at the entrance to the nozzle.
It is found that injecting powder with gas produces a drastic effect on the bubbling-jetting transition. The critical gas flow velocity for the initiation of jetting decreases in powder injection with increasing solid-to-gas mass ratio. This decrease in the critical gas flow velocity is found to become a larger extent for powders of smaller size. These findings could be ascribed to the fact that the velocity of sound of gas solid mixtures decreases with increasing the mass ratio and this decrease in the sonic velocity becomes a larger extent for powders of smaller size.

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The corrosion mechanism of mild steel in CO₂ bearing water has been studied by examining electrochemical behavior of carbonic substances, i.e., H₂CO₃ and HCO^-₃. These substances contribute to the cathodic reaction on the steel surface corroding in CO₂ bearing waters. In the low pH region, the corrosion rate is controlled by the reduction rate of H₂CO₃ and is much higher than that in non-carbonic solutions of the same pH. In the high pH region, however, the corrosion rate is controlled by the stability of the FeCO₃ film that forms on the steel surface.

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The amounts of nitrogen and oxygen absorbed during tapping from the converter were estimated.
It is found that the mass transfer coefficient of nitrogen in the liquid phase during tapping becomes the large value of 0.1-0.2cm/sec due to the violent agitation of molten steel in the ladle.
Absorption efficiencies of nitrogen by air entrainment, η_E, and through the surface of tapping stream, η_St, decrease with increasing oxygen content in the molten steel.
Although the amounts of nitrogen and oxygen absorbed during tapping are practically independent of the tilting rate, the heat size and the profile of the converter, those decrease with decreasing tapping height and somewhat increase with increasing slag depth in the converter. It is also estimated that those amounts increase with decreasing tapping hole diameter and with increasing its length.
A nomograph for the estimations of oxygen and nitrogen absorption by the gas entrainment and also through the surface of tapping stream was proposed.
The estimated amounts of nitrogen absorbed during tapping agreed well with the values reported in the literatures.

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An attempt was made to predict the cooling transformation over the entire range of pearlite reaction, from the isothermal transformation kinetic data. A kinetic equation of pearlite transformation during cooling was derived by applying an additivity rule to the transformed fractions. A good agreement was observed between the measured and calculated cooling transformation curves although the pearlite reaction would not precisely satisfy any one of the additive conditions. A possible deviation of a cooling transformation kinetics from that estimated with the additivity rule was considered based on the nucleation and growth process. It was found that the transformed fractions of pearlite appeared to be additive firstly because the change in the ratio of the nucleation to the growth rate as a function of supercooling was small, and secondly because the cooling transformation occurred either nearly isokinetically when the cooling rate was slow or almost in the condition of site saturation when the cooling rate was fast.

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In contrast to the ordinary ferritic steels, the fracture toughness of 9% Ni steels was found to increase with the strain rate at -196°C. The transition of the fracture mode from brittle to ductile took place at an intermediate strain rate corresponding to the crosshead velocity of 100mm/ min above which the fracture was completely ductile. These observations are attributed to the temperature rise at the crack tip due to the adiabatic heating at high strain rate, which is emphasized by the decreased specific heat and the thermal conductivity at -196°C. The temperature rise during fracture was experimentally confirmed to be 188°C at the maximum.

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The Japan Iron and Steel Federation organized the Committee for Research and Development of the Formed Coke Manufacturing Process in order to establish the continuous manufacturing technology of formed coke as an effective measure to cope with the rapidly diminishing availability of coking coal resources. The Committee began its activities in August, 1978, when it received a research grant from the Government. The present Committee members are Kawasaki Steel Corporation, Kobe Steel, Ltd., Nippon Steel Corporation and Nippon Kokan K.K.
This paper deals with the following aspects of the Committee's joint research: the objectives and progress of the research, the outline of the manufacturing process being developed and its feasibility study, the research project for pilot plant tests, the experiments made for the pilot plant design and process improvement, and the schedule of future research.

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Grooveless rolling is a new method which in corporates flat rolls for the production of billets and bars. This method has been researched and developed in a billet mill at Mizushima Works and applied in practice with many benefits. The points in order to achieve this technique are shown as follows.
1) Design of pass schedule,
2) Design of guides,
3) Technique for preventing overlaps.

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Using the empirical relation suggested by G. M. Sellars and W. J. McTegart, to correlate stress, strain rate and temperature, nomograms were built allowing the rapid calculation of maximum stress values for a wide range of hot working conditions in different steels.

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