In a high speed cold rolling of tinplate, defects called heat-scratches or heat-streaks appear on the surface of rolled strip. These heat-scratches reduce the rolling efficiency, surface quality of rolled strip, rolling oil cost, and so on. To reduce these defects, we have examined the lubrication in high speed cold rolling and developed rolling oil for high speed cold strip rolling by adding an extreme pressure agent (EP agent) and an emulsifier to palm oil.
The main results are as follows:
(1) It is suggested that lubrication state in high speed cold rolling is a mixed state of hydrodynamic lubrication and boundary lubrication which is the main part.
(2) By the addition of 1% EP agent and 0.5% of emulsifier to palm oil, oil film strength is increased 4 times as much as that of neat palm oil, and coefficient of friction is decreased.
(3) Lubrication performance of rolling oil is improved by the addition of EP agent and emulsifier, and it becomes possible to use palm oil emulsion of which concentration is lower (15-20%) than before (25-30%). As a result, heat-scratches are eliminated and rolling speed is increased. Still more, the rolling oil cost is decreased.

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In June, 1977, No. 6 Blast Furnace at Chiba Works of Kawasaki Steel Corporation, was blown in as the largest bell-less top equipped furnace in Japan. Although troubles, such as tuyere bending and burning-out attributable to inappropriate gas flow distribution, were encountered at the initial stage, the results of a series of operational experiments were conducive to improving the in furnace conditions. Especially, the tests designed to determine the optimum charging sequence for coke and ore produced the following achievements:
1) The CO gas utilization ratio (out of the top gas) improved to about 54%.
2) No tuyere burn-outs since April, 1979.
3) A considerable decrease in the thermal load on the furnace shell.
Furthermore, very low fuel rates followed these improvements: a monthly average of 418.4kg/mt-h•m in March, 1980; and a yearly average of 436.1kg/mt-hm•m for the one year period from April, 1979 to March, 1980.

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The dynamic recrystallization behavior of austenite in an 18-8 stainless steel and an 18 Ni maraging steel was studied mainly by microstructural observations of the specimens which were water-quenched immediately after the tensile deformation to various strains at temperatures ranging from 800 to 1200°C and at strain rates of 10^-3-10^-1 s^-1, The changes in austenite grain size and hardness at room temperature due to the dynamic recrystallization were also studied.
The deformation conditions for the occurrence of dynamic recrystallization in both steels were made clear as a function of deformation temperature (T), strain rate (ε) and strain (ε). Dynamic recrystallization takes place under the deformation conditions with Z (Zener-Hollomon parameter) less than the critical value of Z_c. Z_c increases as the amount of strain given by the hot deformation is increased or the initial austenite grain size is decreased. The addition o f Cr seems to have the retarding effect on the occurrence of dynamic recrystallization of austenite. The dynamically recrystallized grain size (D) is determined only by the deformation condition z, and does not depend on the strain and the initial grain size. D is decreased with increase in Z. The room temperature hardness of dynamically recrystallized austenite in 18-8 stainless steel and the martensite formed from the dynamically recrystallized austenite in 18 Ni maraging steel is higher than that of conventionally heat-treated specimens. However, such an increment of hardness due to dynamic recrystallization is not so large.

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The vapor pressures of phosphorus gases, P and P₂, above Fe-P alloys have been determined by a newly developed experimental method. In this experimental method, phosphorus in the deposit film obtained by the Knudsen effusion method with collection technique was determined by a secondary ion mass spectrometer. The vapor pressures of P and P₂ have been obtained from these determined values and the ratio of the ion currents of P⁺ to those of P⁺₂ which had been obtained by the ordinary Knudsen cell-mass spectrometer combination. The standard free energy changes of the reactions for liquid Fe-P alloy system were calculated from these vapor pressures, and the following values have been obtained.
P(g)=P(wt%)
ΔG°=-95.3+1.55×10^-2T(±2.2)(kcal/mol)
1/2P₂(g)=P(wt%)
ΔG°=-37.7+0.13×10^-2T(±1.1)(kcal/mol)
P(g)=1/2P₂(g)
ΔG°=-57.6+1.42×10^-2T(±1.1)(kcal/mol)
(1-3wt% P, 1590-1650°C)

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An analysis is given of solute segregation in solidified samples caused by interdendritic mass flow of solute-rich liquid to feed solidification contraction. Calculations are presented for solidification of Fe-C-P ingot with an abrupt change of cross-sectional area. Noticeable solute-depleted bands with sharp peaks are predicted to form in the vicinity of the section of area reduction. The severe segregation peak is calculated to be produced with the large area reduction.
To clarify the mechanism of formation of negative segregation a series of experiments of uni-directional solidification has been done. A clear negative segregation has appeared in the solidified sample. Extent of segregation is larger for phosphorus than carbon. Reasonable agreement of prediction of the model with the experiment has been obtained.

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A mathematical model for estimating the profile of softening-melting zone and the radial gas distribution in the furnace in operation has been developed by use of the measured shaft gas pressures in the furnace.
Close agreement was obtained between the results of this estimation and the data obtained with other instruments in the furnace, and the accuracy of this estimation was satisfactory.
Indices representing the operation state in the furnace have been derived based on the results of this estimation, and the usefulness of these indices was confirmed for the control of the thermal efficiency, reducibility, molten metal quality, permeability, materials descending state, and so on.
Further, operation states were analyzed in the case of a decrease in production and an increase in pellet ratio in burden based on the results of this estimation, and it was shown that the actual phenomena in the furnace could be analyzed sufficiently and accurately.

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When the productivity of No. 2 blast furnace at Sakai Works, Nippon Steel Corporation, was cut down from 2.08t/d•m³ because of the economic deterioration in Japan in the latter half of 1970's, coke was sampled at the tuyere level seven times in the course of the cutdown.
On the basis of the test result of the properties of coke sampled, the followings were concluded:
(1) As the production rate decreases, the point of the maximum temperature in the raceway moves toward the tuyere and the temperature of the dead-man decreases.
(2) Coke becomes fragile because of the long time exposure to high temperatures at the lower part of the furnace. Therefore, the amount of coke fines in the raceway increases with increasing kinetic enemy of blast, and in consequence, gas flows upward rather along the wall side than in the center.
On the other hand, the decrease in the amount of coke fine, which is brought about by the decrease in the kinetic energy of blast, results in a smooth operation which is attributed to the uniform gas distribution. However, in the case of lower kinetic energy of blast, the temperature of the deadman decreases and, consequently, softened and half-melted materials form in the region.

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