There are two kinds of cinders, obtained as the residue in sulphuric acid plant. One is mainly composed of Fe2O3 (Pyrite cinder Py-C) and the other is mainly composed of Fe3O4 (Pyrrhotite cinder Pr-C). To clarify differences of the reducing behavior between these two cidners. The cinders were investigated as follows: (1) Measurement of high temperature permeability at various temperature. (2) Degree of reducibility. The main results were as follows: (1) Py-c was reduced easier than Pr-c by CO and solid C. (2) High temperature permeability of Py-c was better than that of Pr-c.
No. 2 blast furnace in Kokura Steel Works which started in January 1951, is now producing the low copper, low sulphur pig iron to be used for steel plants. Recently, in order to increase the output, to decrease coke ratio and to improve the pig quality, improvements in the blast furnace practice was thoroughly performed as follows: 1) Preparation and controlled use of raw materials was more improved. 2) Sinter production was increased more and sinter qualities were more improved. 3) In the furnace operation, the slack-wind-blowing was practiced and the blast pressure was controlled and charging method was found out the best. 4) Tuyeres were changed from the circular type to the elliptic type. As results of this improved operation, espectally the output increased to over 400t/day, and the coke ratio decreased below 0•700, during the period from December 1953 to April 1954. This improvement presumably depends mainly on the better sizing of raw materials as well as on the furnace operation matched for it.
The authors studied on the corrosion of chamotte bricks by various molten steels, with the reformed crucible method. The results obtained were as follows: (1) The corrosion of chamotte bricks by the molten steel were influenced by the [Si], [Mn] and [FeO] in the molten Steel The [Mn] and [FeO] promote the corrosion and, the [Si] hold in check. (2) If the elements which have great affinity for oxygen were presence in the molten steel, the corrosion decreased. (3) The corrosion by molten iron and [FeO] increased hastily when [Mn] content in the molten steel decreased. (4) The corrosive reaction is then According to results of this study, the corrosion by [Mn] in the molten steel is slight in comparison with the corrosion by molten iron or [FeO]. Specially as the [Mn] content is low the controlling reactions for corrosion are (1) and (3) reactions.
The authors studied the process of the desulphurization of molten pig iron with calcium carbide or calcium oxide powder by injection with carrier gas such as nitrogen or air. The results obtained were as follows. (1) The highest desulphurizing efficiency was found in case of using the calcium carbide as desulphurizing agent and carrier gas as nitrogen. (2) At the temperature above 1350°C, the sulphur was removed easily to 20 per cent or less of the initial content, by injection of 1 per cent calcium carbide. (3) Calcium carbide did not affect the other chemical compositions and nitrogen gas was not insoluble in molten iron. (4) As the carrier gas, air was used instead of nitrogen, but the desulphurizing efficiency was more or less lower. (5) Calcium oxide was less effective than calcium carbide. Through the industrial application of this study, the desulphurization of few thousand tons of iron was achieved, and subsequeittly good castings were produced during the past 6 months.
The authors made a study of the heat efficiency of large batch type reheating furnaces that were possible to heat 6t-120t ingots, and then comprehended following matters. 1. When the weight of charged ingots per unit volume of heating chamber incressed, the heat efficiency increased, but it stopped at some point. 2. When the ratio, of areas of the heated ingots surface and the inside wall of the furnace increased, the heat efficiency increased. But there was a limit, because the ingots must have been heated uniformly. 3. The total quantity of heat that was stored in the furnace wall and was radiated from the outside of the wall, was by more than 50% less in the case insulated than the case not insulated. 4. The weight of charged ingots per unit hearth area and combustion heat per unit volume were determined by the ingots size, because ingots must have been heated uniformly. 5. It was desired that the many ports should be set in the low position, and at the same time checkers should be large and deep.
The drawing stress and the plug stress of the tube drawing were studied. At first, the particular drawing process was analysed, where the wall thickness of tubes was reduced, the internal diameter being kept constant, and then the general tube drawing process was investigated where the tube diameter and the wall thickness were also reduced. The latter case was assumed as a single plug drawing process under the back tension, induced by the drawing stress of initial sinking process. But from the experimental results that the influence of the die angle on the drawing stress of thin wall tubes was smaller than that calculated from the above mentioned method, the author introduced the new "sec α type" term. In case of sinking, other two additional terms were introduced, which were the functions of the die angle and the wall thickness. In case of plug drawing, other 4 additional terms of the drawing stress were introduced, namely two terms for additional shear strain similar to sinking, the term for friction of die bearing and the term for resistance force from the plug which was introduced by the bending of metal flow at outlet of the die. The additional terms for the plug stress were the term for friction of die bearing and that of resistance force from the plug at outlet of the die.
The experiments herein introduced were made to clarify the tensile, impact, fatigue and creep strength of 13% Cr steel at high temperatures, and the effect of non-metallic inclusions and the Mo on the mechanical strength of the alloy. In the experiments on the effect of non-metallic inclusions, four types of specimens were used, which contained 0•13 to 0•20% C, 12•69 to 13•13% Cr and various quantities of nonmetallic inclusions. For testing the effect of Mo, five types of specimens containing 0•09 to 0•17% and trace to 1•06% Mo were employed. The results are summarised as follows. (1) Tensile strength is not affected by the non-metalljc inclusions. (2) With the increase of temperature, the tensile strength and the fatigue strength decrease, but endurance ratio, (i. e. fatigue strength divided by tensile strength, ) increases. (3) The impact value is lowered by inclusions only slightly at room temperature but considerably at high temperatures. (4) Rotating -bending fatigue strength decreases with the increase of inclusions on the stressed surface. (5) Addition of Mo increases the tensile strength and particularly creep strength at high temperatures, but affords no change in fatigue strength. 13% Cr steel containing 1.06% Mo has about twice the creep strength of that containing no Mo.
The effects of Si and C contents on the mechnical properties, corrosion resistance, shrinkage and microstructure of acid-resistant high-silicon irons were investigated. The results are summparized as follows: (1) The corrosion rapidly decreases with increasing Si and the maximum resistance reaches about 15•5 pct of Si against sulphuric acid (sp. gr.1•10) and about 14 pct of Si against hydrochloric acid (sp. gr. 1•09). (2) In the practical alloys containing 14-16 pct of Si, the transverse strength is higher in the alloys with lower Si and higher C contents (0•6-0•8 pct), with medium Si and medium C (0•5-0•7 pct) and with higher Si and lower C (0•3-0•5 pct). (3) The deflection is very small and the ductility seems to increase slightly as the Si content becomes lower or the C content becomes higher.(4) The micro-Vickers hardness of the α-phase increases with increased Si content up to about 15 pct, above which there is very little change. (5) The shrinkage shows maximum value at the alloys containing 15•5-16•0 pct Si and the effect of C on the shrinkage is small. (6) The shape and type of graphite greatly infiuence the Rockwell hardness and transverse strength. The η-phase (Fe5Si3) found in high Si alloys decreases the strength.
High purity chromium and chromium base alloys have excellent oxidation resistance and strength at high temperature. But they have never been used as heat resistant materials, as they are extremely brittle at room temperature. A recent research dy Wain and Greenaway, however, gives a great promise to this problem. They have succeeded in the preparation of chromium and its alloy which show a room-temperature ductility by very careful purification and mechanical working. This paper summarizes many researches, including Wain's, on the production and properties of high-purity chromium.