In order to understand the effect of sulphur in reducing gas on the reduction behavior of iron oxides, the reduction experiments were conducted in H₂-H₂S mixtures with various sulphur activities at 1 000 and 1 200°C.
Macroscopic reduction patterns of pure wustite pellets can be divided into seven types, depending on the porosity of pellets and the activity of sulphur in the gas. This classification is slightly modified by the addition of MgO and CaO.
The reduction of pellets with low porosity is retarded greatly due to the formation of iron-oxysulphide liquid. The retardation of reduction does not occur with pellets of high porosity even under the high sulphur activity to form FeS. However, the reduction is retarded provided that the sufficient amount of the liquid to fill up the pores is formed.
The activity of sulphur in equilibrium under iron, wustite and iron-oxysulphide liquid was determined experimentally. MgO in wustite raises the sulphur activity and CaO lowers it.
Sulphur in the gas without the formation of sulphides causes the topochemical reduction pattern, independently of the presence of foreign oxides.

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ウスタイトのCO-H₂混合ガスによる還元速度に関して,未反応核モデルに基づく数式モデルを展開した.このモデルにおいて,
(1)還元鉄を触媒とする水性ガスシフト反応を考慮に入れた.
(2)ガス境膜および生成鉄層内のガスの拡散速度は多成分系のSTEFAN-MAXWELLの式によつて推算した.
緻密なウスタイトの薄板のCO-H₂混合ガスによる還元実験を1000℃において行い,そのデータをこの数式モデルを用いて解析した.その結果,次のことがわかつた.
(1)水性ガスシフト反応の影響は無視できるほど小さい.
(2)還元速度のガス濃度への依存性は加成性から負に偏倚する.その理由はガス境膜および生成鉄層における拡散抵抗の寄与が大きいためである.

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The thermodynamics of phosphate and phosphide in BaO-BaF₂ melts was studied by equilibrating the melts in a graphite boat with CO-Ar mixtures and Ag-P alloys between 1 200°C and 1 450°C.
The concentration dependence of both constituents on the partial pressure of phosphorus and oxygen, the melt composition and temperature was determined.
Comparing with the CaO-CaF₂ system previously reported by the authors, BaO-BaF₂ melts were found to have a larger capacity for phosphate by an order of magnitude but nearly the same one for phosphide.
It is concluded that BaO-BaF₂ melts are very effective in removing phosphorus from other systems under either oxidizing or reducing conditions.

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The information of thermodynamic properties of phosphorus in lime bearing slags at low temperatures is required in connection with the recent progress of hot metal treatment.
In the present study, the equilibrium distribution ratio of phosphorus (L_P) between CaO-CaF₂-SiO₂ melts saturated with CaO, 3CaO·SiO₂ and/or 2CaO·SiO₂ and carbon-saturated iron was measured under CO atmosphere at temperatures ranging from 1 200 to 1 400°C, keeping in mind that the industrial flux always contains some undissolved solids.
The results are summerized as follows :
(1) L_P increases with increasing CaO content and has a maximum when the slag is saturated simultaneously with CaO and 3CaO·SiO₂.
(2) Phosphate capacity was confirmed to be independent of the oxygen partial pressure by using ironcarbon melts equilibrated with austenite and CO at 1 300°C. The phosphate capacity in basic regions of this system is much greater than other lime bearing slags.
(3) CaF₂ is more effective for dephosphorization than CaCl₂, probably because the interactions between fluorine and phosphorus and between fluorine and calcium are stronger than those between chlorine and phosphorus and between chlorine and calcium, respectively.
(4) L_P increases significantly with a small Na₂O addition to the CaO-CaF₂-SiO₂ system. This result indicates that the costly soda ash treatment can be replaced by using lime based fluxes containing a little soda ash.

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Experiments of the dephosphorization of molten iron containing chromium (≤27 wt%), carbon (≤6 wt%), and phosphorus (0.1, 0.04 wt%) by the use of the flux of Na₂O-SiO₂-NaF system were carried out in the temperature range from 1 300°C to 1 600°C.
Effects of flux composition, carbon and chromium content in molten iron and temperature on the dephosphorization were made clear.
Relations between phosphorus and chromium distribution ratios obtained at the end of runs and carbon content in molten iron were also investigated. These distribution ratios depend on the carbon content strongly.

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To separate inclusions from molten steel, a new method by filtration which is different from conventional ones based on floating-out of inclusions was investigated. Since filters with pores smaller than the diameter of inclusion are considered not to be applicable to molten steel, ceramic filters with many small holes were used with expectation of getting inclusions adhered on them.
As the first step the influences of filter shape design and deoxidation of steel on the filtration of inclusions were investigated.
Results obtained are summarized as follows:
(1) The inclusions filtered are only of alumina type and therefore this filter is effective for removal of inclusion in aluminum killed steel.
(2) Inclusions adhere at first on the edge of a filter pore where the flow of molten steel changes and grow to cover on the top surface of the filter and fill up the inner part of the pore. When the layer of adhered inclusions on the filter becomes thick, the molten steel can not go through the filter.
(3) From the reason mention above, the increase of thickness of the filter dose not improve removal of inclusions.

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The authors investigated the method to get the sound heavy gauge plates only by rolling process, and developed the Low-speed Heavy Reduction Rolling process, the purpose of which was to secure the necessary temperature, time and compressive stress for annihilating micro porosities. Furthermore, taking notice that most of micro porosities are distributed in the about 50-60% region of mid-width of ingots, they have developed the Center-portion Heavy Reduction Rolling process which reduce only the high density area of micro porosities partially by the low speed and heavy reduction rolling. In such a partial rolling, the compressive stress in midthickness increases notably as a result of the binding force caused by the un-rolled edge parts and an increase in the reduction amount per pass.
It would be possible to manufacture the sound heavy gauge plates stably from the conventional ingots by the application of this developed rolling process.

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LHC 遠心噴霧法により製造した Ni 基超合金粉末の製造条件と粉末特性および組織微細度 (S_II) との関係について検討し, 以下の結果を得た.
まず粉末の最頻出粒径 (d_m) は主に回転ディスクの周速度に依存し,ディスク径が一定の場合, 回転数 (R) の R^-0.84に比例して細粒化する. また, 回転ディスクの材質により粉末形状が変化し, 熱伝導のよいグラファイトを使用した場合, 最も球状化する. 通常, 超合金粉末はキャニング⁵⁾された状態で冷間または熱間加工される都合上, 充填率の高い球状粉末が好ましいと考えられる.
次に溶質偏析の一つの尺度¹⁷⁾となる2次デンドライト・アーム間隔(S_II)は, 回転ディスクの周速度 (DR)^0.17に反比例し, 粉末が細粒化するほど減少する. すなわちディスクの回転を増速することが最も効果的である. さらに, 噴霧粒子の冷却には H₂, He など熱伝導度のよい冷却媒を使用し, 液化ガスの導入量を多くすると同時に, 雰囲気圧力を高めることも有効であることがわかつた.
なお, 本研究は通産省工技院のプロジェクトである 「次世代産業基盤技術開発」 の一環として実施したものである.

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The effect of solution and aging treatment on the grain boundary reaction (GBR) as well as on the general precipitation in the interior of grain (GP) was investigated for Co-base superalloy HS-21. The GBR occurred during furnace-cooling after solution heating, and the maximum amount of it was obtained in the temperature range from 1 523 K to 1 548 K. The GBR that occurred during aging was considerably influenced by the cooling procedure after solution heating. A large amount of GBR was observed in the specimen directly quenched. In the air-cooled specimen, the amount of GBR was less than one half of that observed in the directly quenched one, while very few amount of it was observed in the water-quenched one. The extent of GP that occurred during aging was also affected by cooling procedure, and the maximum amount of it was obtained in the water-quenched one.
Creep rupture life was longer on the specimen with a small amount of GBR with GP. The improvement of rupture life resulted from the retardation of grain boundary sliding by the zigzag grain boundary owing to the GBR and by the increase of strength in the interior of grain due to the GP.

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There is a limit to grain refinement of high-speed tool steel by usual recrystallization process at the austenite region even after working with a large reduction.
In a series of our experiments, however, it was shown that in steel specimens processed through preforming and then solution treatment, the grain size after recrystallization was extremely refined. Tests carried out in a range of commercial high-speed tool steels quantitatively clarified the effect of preform reduction, solution temperature, reduction for recrystallization and annealing temperature on the final grain sizes.
Furthermore, it was shown that high-speed tool steel with fine grain sizes was possible to become superplastic and its total elongation exceeded 300% over a suitable range of temperatures and strain rates.

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積層欠陥エネルギーが異なる5種類の Fe-Cr-Ni系オーステナイトステンレス鋼の塑性変形挙動を調査した結果を以下のようにまとめることができる.
(1)応力-ひずみ関係において降伏応力の積層欠陥エネルギー依存性は乏しいが, 加工硬化率およびある程度大きい歪みでの変形応力は, 積層欠陥エネルギーに依存し, 低積層欠陥エネルギーの合金ほど高くなつた.
(2)コットレル・ストークス比は, 変形応力の非熱成分および熱成分の相対的寄与の尺度を示しており, この比が積層欠陥エネルギーの増加に対してほぼ直線的に増加することから, 高積層欠陥エネルギーの鋼ほど, 非熱成分の寄与する割合が大きくなることが判明した.
(3)活性化体積は, 高積層欠陥エネルギーの鋼ほど小さくなり, またそのひずみに対する変化の度合は, 高積層欠陥エネルギーの鋼ほど大きかつた.

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(1)有機被覆鋼板は, 有機被覆層が健全な場合非常にすぐれた防食性能を有するが, 有機被覆層に損傷が生じた場合にその性能が著しく低下し, 特に鋼板素地に達する切り欠きが存在すると冷延鋼板に近くなる.
(2)すなわち, 有機被覆層中の亜鉛粉は, めつき層の亜鉛と根本的に異なり, 犠牲防食効果を有しない.
(3)めつき層と有機被覆層との複合被覆鋼板のそれぞれの被覆層は, 単独の被覆層に比べて, ほぼ2倍の防食性能を有すると推定される.

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The improvement of chip-disposability has a primary importance in the automation of machining process and the use of unmanned machine tool.
Chip-disposability and tool wear during turning of low alloy steels having ferrite and martensite phases were examined. The experimental results showed the chip-disposability was remarkably improved in the steels mixed with martensite, compared with the spheroidized or normalized steels.
In steels which were mixed with martensite and had the hardness of HV 200350, chips in the high cutting speed region were broken below one curl. The influence of martensite phase on the chip-disposability was discussed through the observation of the microstructure and surface shape of chips.
The wear of hard metal tool in the cutting of steel mixed with martensite tempered at about 300°C was similar to that of the spheroidized steel, and the tool life time of high speed steel tool for the steel tempered above 400°C was considerably longer than that for the steel tempered at 300°C. When the cutting was done with high speeds using a cermet tool, the tool wear for the steel mixed with martensite and not tempered was larger than that for the normalized steel.

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