There have been problems on fluorescent X-ray analysis of iron ores by the glass bead technique. Of these, the influence of combined water on the analysis of total iron content and that of coexistent elements on the analysis of SiO₂ and CaO contents have been studied. In this investigation sodium tetraborate was used as fusing flux.
The results were as follows.
(1) The influence of the combined water on T.Fe content determination was theoretically studied. The FeKα intensity was calculated in the Fe₂O₃-H₂O loss sample system which was produced when water escaped from Fe₂O₃-H₂O binary sample by, fusing and heating. Its intensity was higher than in Fe-O binary system sample on the standard calibration curve, at the same T.Fe content.
From the calculated change of the FeKα intensity, correction factors were derived. Goethite which had 10.1% CW was analysed more by about 0.5% T.Fe.
(3) The influence of coexistent impurities (elements), on SiO₂ and
CaO content determination was theoretically studied. The SiKα and CaKα intensities were calculated in SiO₂ Fe₂O₃-impurity and CaO-Fe₂O₃-impurity systems, respectively. Further, correction factors were derived when calibration curves were for SiO₂-Fe₂O₃ or CaO-Fe₂O₃ system samples. The influence of coexistent elements on the SiKα and CaKα intensities was little.
(3) Analytical experiments for JSS standard samples showed that the theoretical results of (1) and (2) described above agreed well with experimental ones.

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on the basis of the results of dissection of Nagoya No. 1 blast furnace, studies have been made on the degradation of coke in a large blast furnace. The results o f these studies show as follows.
(1) The degradation of coke in a blast furnace is greatly influenced by the temperature wherein coke is subjected to the CO₂ reaction.
(2) Lump coke, which begins to degrade due to the selective solution loss and the decrease in strength at 1 000°C, does not change the grain size up to 1 400°C but begins to reduce the size markedly above 1 400°C.
(3) Coke fines deposited between the lower part of shaft and the tuyeres are concentrated in the vicinity of raceway and moved by the kinetic energy of gas.
(4) The increase in the alkali content of coke (by 5% maximum in the present study) does not decrease the strength of coke. Further, the relationships between the inner volumes of dissected blast furnaces and the change in the properties of coke charged in furnaces were studies. The results of this study suggest that the size reduction ratio of coke particle is higher and the degradation conditions of coke become more strict in the case of large blast furnace than that of small one.

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Transient measurements have been made of the cylindrical metal temperature upon an impingement of a single water droplet on its circular surface preheated to a specified temperature of 300 to 450°C. Results can be well explained by means of the axisymmetric three-dimensional model for conduction in metal and heat transfer coefficient between the surface and droplet has been estimated as the model parameter. Numerical values of the heat transfer coefficient obtained with stainless steel rod specimen seem to correspond with the interpolated ones of the previous results, 2) which were obtained by the stationary method with a thin circular plate of stainless steel. Heat transfer coefficient is a function of the thermal diffusivity of hot metal as well as both Weber number of the droplet and the surface temperature of metal.

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Since 1978, the oxygen sensor has been improved for the determination of the dissolved oxygen less than 50ppm in order to control the precise content of Al in killed steel in Japan as well as in other countries. The present authors have studied on the oxygen sensor for molten slag and the long-life oxygen sensor developed as monitors of the oxygen pressures in molten iron and slag in a converter, a tundish of continuous casting and a blast furnace. The present report gives the authors' investigation on the number of the oxygen sensors consumed by ten Japanese steelmaking companies in the years 1977, 1980 and 1982 with the examples of new applications of the oxygen sensor.

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Advanced mathematical models for plate mills including a plate crown model and a plate flatness model were developed for draft scheduling. These models have the following features:
(1) Optimum draft scheduling is possible by a special plate crown model.
(2) Accurate plate temperature estimation is established.
(3) A rolling load model which will cover a wide range of rolling conditions was developed.

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With the aim of establishing laboratory methods of scab corrosion tests for automobile bodies, the influences of wetness duration in environment and the shape of damage on 3-coated test panels have been studied by cyclic corrosion test (CCT).
The wetness duration fraction was defined as the percentage of the wetness duration in one complete cyclic corrosion test.
Painted test panels, subjected to the CCT in which the wetness duration fraction is more than 50%, develop blister widths on scribed, damaged panels of electrogalvanized steel that are larger than those formed on cold rolled steel. An opposite effect is observed when the wetness duration fraction is lower.
Comparison of the above result with the data obtained from outdoor exposure test and actual car bodies has demonstrated that for scab corrosion test the wetness duration fraction in one cycle should be less than 50%.
From the measurements of pH values around scribe damage and the galvanic couple current which flows between electropainted test panel and cold rolled bare steel, it is suggested that the scab corrosion propagates by the dissolution of substrate metal at the blistering front.

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API Buttress Thread Connection (B.T.C.) has high joint strength, but lacks internal pressure sealability. A spiral leak path of threading tolerance on the mating surface causes the leakage.
With an object of improving seal capability of the joint, thick tin plating was applied on the threads of coupling to fill the potential leak path.
However thick plating increases thread interference, which might influence the joint performances. Therefore optimum plating thickness should be determined taking these into account
.Makeup tests, hydrostatic internal pressure leak tests and joint tensile tests were conducted to study the joint properties. Samples of three different plating thickness levels-20μ, 60μ and 120μ-were tested.
As the results of the tests,
(1) Thick tin plating improves the sealability of a Buttress Thread Connection.
(2) Makeup stress and the first part of makeup torque increase in proportion to the plating thickness.
(3) Joint strength was not influenced by the tin plating on the thread. And at last, 60μ level tin plating thickness is considered to be the most pertinent for a Buttress Thread Connection to improve the sealability without decreasing the other joint properties.

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In order to elucidate the mechanism by which the surface quality of steel products containing a small amount o f Mo is noticeably improved, hot cracking in the grain oriented silicon steels containing 0.013% Mo and in steel containing no Mo has been investigated by the impact experiment. In the impact experiment after slab soaking, and under elevated temperatures the intergranular fracturing of silicon steel containing a small amount of Mo is found to be less than that of Mo free steel.
In Electron Probe Micro Analysis (EPMA) and Glow Discharge Spectrometry (GDS) measurements after slab soaking, Mo segregates preferentially in the vicinity of the surface in the silicon steel containing Mo.
It is concluded that, because of the preferential segregation of Mo in the vicinity of the surface of silicon steel containing a small amount of Mo during slab soaking or hot rolling, intergranular fracturing is inhibited, and, consequently the surface quality of final products is noticeably improved.

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The transmission Kossel (TK) technique has been applied in an attempt to elucidate the origin of potential nuclei of the celebrated (110)[001]secondary grains in hot-rolled sheets of high induction grain oriented silicon steel containing a small amount of Mo. It is observed in the microstructure in the vicinity of the surface of the hot-rolled sheets that the development of recrystallized grains is noticeably retarded and the polygonized {110}• <001> grains are preferentially, formed. In TK measurement there are two types of polygonized {110}<001> grains at a depth of 1/10 the sheet thickness under the steel surface; large polygonized (110)[001] grain possessing highly oriented (110)[001] areas with sharpened TK patterns and small polygonized {11O} <001> grains with all the diffused TK patterns. The highly oriented (110)[001] areas inside the former large polygonized (110)[001] grains are the origin of the potential nuclei of (110)[001] secondary grains. The frequency of generation and the areal fraction of (110)[001] secondary nuclei in the hot-rolled steel containing a small amount o f Mo are approximately three times as large as those found in steel containing no Mo. It is believed that the high induction grain oriented silicon steel containing a small amount of Mo has lower iron loss due to the development of (110)[001] secondary grains having small grain sizes.

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Low cycle fatigue behavior of two Ni-Cr-W alloys (KSN and 113MA) was investigated at 1 273K in the simulated High Temperature Gas-cooled Reactor (HTGR) helium, He-2. Both alloys showed little cyclic hardening in fatigue tests and failed with a completely intergranular manner. Although the fatigue life (N_f) of 113MA was a little longer than that of KSN, observed intergranular fractures indicated that the fatigue properties of both alloys were severely influenced by impurities in He-2.
As well as in He-2, fatigue tests of KSN and 113MA were carried out in pure He, air and vacuum. The results clearly showed that, regardless of the concentration of reactive gases, both alloys failed intergranularly with short N_fs in gas environments, as compared with the transgranular fracture with long N_f in vacuum. A minor effect of impurity contents was shown as an increase in N_f when substituting air by He-2 and then by pure He. It is considered from these behaviors that the fatigue fractures were affected by residual oxygen gas in the environments penetrating into the specimens along the grain boundaries.

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The effects of thermal aging on the low cycle fatigue behavior of Ni-Cr-W alloys were investigated on KSN alloy (Ni-15wt%Cr-25wt%W) at 1 273K in the simulated helium (He-2) for High Temperature Gas-cooled Reactor (HTGR). Fully reversed strain control tests were made at a strain rate of 1×10^-3 s^-1 with holdtimes of 0, 6 and 60min. The thermal aging at 1 273K for 1 000hr initiated the precipitation of α₂ phase (bcc-W) in the matrix and on grain boundaries of KSN.
Although a degradation of fatigue lives was observed with increase of the period of holdtime for both solution annealed and aged KSN (KSN-SA and-AGE), the value of fatigue life was significantly longer for KSN-AGE than for KSN-SA. The morphology of intergranular fracture of two materials indicated that the existence of α₂ particles at the grain boundaries increased both cycles to initiation and those to propagation of fatigue crack. The role of α₂ precipitates was to reduce the weakening of grain boundaries and the oxidation rate by changing the corrosion products at a crack tip from Cr-oxides for KSN-SA to Ti/Al-oxides for KSN-AGE.

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With the intention of improving sinter qualities, it has been developed a image analysis system for quantitative determination of the sinter structure. A prominent feature of this system with an industrial TV camera and a micro-computer is the simultaneous use of a microscope and a microscope, which enables to determine both the macrostructure and the microstructure of a sinter with high accuracy. A few runs of measurement were made on commercially produced sinter to ascertain the effectiveness of this system.

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