The reaction rates were measured for desulphurization of the molten Fe-S-X and Fe-S-C-X alloys with hydrogen and oxygen gas, where X represented for the elements added such as C, Si, Al, Ni, Cr, Mn. As the results, the following was found: The reaction rate increased by addition of carbon, silicon, aluminum and decreased by that of manganese, and were not influenced by that of nickel and chromium. The effects of the elements added on the rate corresponded to the activity of sulphur in the melt. The relation between the specific rate constant K and the activity coefflcient of sulphur, f was obtained as follows: where f(S)S, f(2)S, etc, were the interaction coefflcient of sulphur. The mechanism of desulphurization by gas was discussed in comparison with slag.
The fracture surface as well as the polished surface of S-H cast iron shows a net structure having a boundary line of light gray color. The microstructure proved that the boundary-line portion was a group of austenite dendrite and that the mesh of net (meshy portion) was consisted of eutectic graphite structure. Both the micro-hardnesses of boundary-line and meshy portions were estimated. The results proved that the hardness of boundary-line portion was about 1.5-2.7 times of meshy portion. The authors presumed that one of the major reasons of the greater wear-resistance of S-H cast iron was based upon the following characteristics: 1. The existence of a unique net structure of S-H cast iron. 2. The presence of a boundary-line portion of greater hardness in the matrix of eutectic graphite structure of lower hardness. 3. The fine and uniform distribution of fine TiC particles in S-H cast iron casting.
In the report I, the author has described the influence of C, Si, Mn, P and S. In the present report, he complements the first report with some additional experimental data, and then describes the influence of Cu and Al. First, another method of testing the hot-tearing tendency is explained. This method, which the author calls test of "C" type, is used in the present study together with two methods already described in report I. The results obtained are briefly summarized as follows: (1) Increase in carbon does not increase hot-tearing tendency in the test of "C" type, while it increases hot-tearing tendency decidedly in the test of "A" type; the influence of carbon on hot-tearing tendency seems to vary, as some other investigators pointed out, with varying types of casting tested. (2) It is quite sure that increasing copper content to 1.5% does not increase hot-tearing tendency in the wide range of sulphur content of 0.01-0.06%. (3) Increasing aluminium up to 1% does not affect the hot-tearing tendency of low-sulphur steel containing about 0.01% sulphur. (4) In high-sulphur steel containing about 0.03% sulphur, addition of 0.1-0.2% aluminium decreases the hot-tearing tendency.
Among the finishing processes of seamless steel tubings, there is one in which outside diameter of tube is reduced hot through die. In this connection, tube-drawing by use of plug is unavailable from the practical point of view, resulting in the ability of free deformation of tubes in the radius direction, and therefore it is impossible for us to estimate the wall-thickness of drawn-tubes. Moreover, we must know the fact that the outside diameter of tube already-drawn becomes smaller than the inside diameter of die. With the above in mind, the author obtained experimentally and made some observations on the variation of wall-thickness and outside diameter of tubes. The results obtained were summarized as follows: 1) The recording of variation of drawing force ouring the hot-drawing operation with an oscillograph, showed that soon after the commencement of the operation, the drawing force shockingly increased, with the values kept almost constant after that. 2) Drawing stress increased in proportion to the reduced rate in area of tube. Any difference due to wall-thickness could not be observed. The relation between the drawing stress σl kg/mm2 and reduction rate ε % at the drawing temperature of 500°C could be shown by the following equation. σl=1.013+0.401 ε 3) The distribution of outside diameter and wall-thickness of drawn tube in the axial direction was found small in the forward portion (pulling side), large in the backward portion. As for the distribution in the middle portion except those above-mentioned, remained almost constantl in case of thin-walled tube, with a tendency to be increased gradually towards the forward portion from the backward one. 4) As the reduction rate of outside diameter increased, the increasing rate of wall thickness became larger up to the maximum value, with a tendency to be decreased in case of thick-walled tube as compared with that of mother tube. 5) The difference between the inside diameter of die and outside diameter of finished tube became larger with the increase of outside diameter reduction rate, to a considerable degree and therefore sufficient consideration should be taken into this fact in the finishing process in question.
At forging direction and its transversal direction in various heavy section of tool steels (Cr cold die steel, Cr-W-V hot die steel and Mn-Cr-W gauge steel), dimension-clange measuring specimen were cut off, and then, the authors investigated directional properties caused by forging and rate of dimension change due to heat-treatment. The results obtained were as follows: 1) In the case of HDC and CRD, forging direction is larger than the transversal directionin the rate of length change and diameter change by heat-treatment generally. 2) In the case of SGT, transversal direction is larger than forging diretion in the rate of length change, but forging direction is larger than transversal direction in the rate of diameter change by heat-treatment.
The duplex-grains of austenite were divided into the "uniform duplex-grains" and the "non-uniform duplex-grains" with regard to its grain distribution pattern and the "duplexgrains in the McQuaid-Ehn grain size" and the "duplex-grains in actual grain size" with regard to the method of revealing them. Thus the effect of duplex-grain structures on properties of steel was studied quantitatively. Carbon steels with 0.30, 0.70, 1.00%C and Ni-Cr-Mo case hardening steels with 0.20%C were used, and with most of these steels impact transition characteristics was investigated systematically, but with some steels tensile properties were also investigated. Results of these investigations and some considerations are summarized as follows; (1) Steels of the "non-uniform duplex-grains" in the McQuaid-Ehn grain size present similar duplex-grain structures also in actual grain size. Steels of the "uniform duplexgrains" in the Mc-Quaid-Ehn grain size, on the other hand, do not always develop duplexgrain structures in actual grain size, but ordinarily present fine-grained structures in it, unless its austenitizing conditions are so high temperature and so long time. (2) Strength and ductility of steels are strongly influenced by their grain distribution pattern in the actual grain size; steels of higher degree of duplexity have lower strength and ductility and steels of the "non-uniform duplex-grains" have much less strength and ductility than those of the "uniform duplex-grains". (3) Steels of the "non-uniform duplex-grains" in the McQuaid-Ehn grain size, therefore, are most undesirable with regard to strength and ductility, and steels of the "uniform duplexgrains" in the McQuaid-Ehn grain size, on the contrary, have ordinarily almost same degree of strength and ductility in actual heat treating conditions as that of steels of "fine-grains" in the McQuaid-Ehn grain size.
For installation of a solution-type reactor, the authors investigated on the selection of various types of home-made stainless steels for manufacture of tanks and pipings of the above mentioned reactor. In consequence, most of corrosion conditions showed satisfactory results within the corrosion rate which is permissible for materials to be used for the ordinary reactor. The corrosion resistance of the parts in contact with the uranyl salt solution in the reactor was found to be more satisfactory if they were used, after they had been immersed in the solution for 1 to 3 days and washed away beforehand.
The precipitated particles were determined by means of X-ray diffraction, electronic microscope, chemical analysis, and selective etching for both of regular 16-25-6 alloy and 16-25-6 alloy containing Ti. Samples for X-ray diffraction test and for an electronic microscope were extracted from aged specimens by electrolytic decomposition in 3% HCl solution. For X-ray diffraction test, there were two methods. One applied the usual X-ray diffraction tester using photograph film, and another used a tester which measured the diffraction and intensity automatically with Geiger counters. The author's data were compared with the known carabides crystallographic data (from ASM Diffaction Data Cards.) It was concluded that precipitated particles in Timken 16-25-6 alloy contained two kinds of carbides, M6C, (Fe, Cr)23C6, at least. These particles were also analysized chemically, and evidence of the presence of nitride was found simultaneously. Presence of σ phase was not found. On the other hand, the carbide M6C was observed through microscope by using selective etching reagent. Thus, with the regular 16-25-6 alloy, it was concluded that precipitated particles perhaps were M6C, (Fe, Cr)23 C6, and Cr MoN2. In the case of 16-25-6 alloy contaning Ti, the intermetallic compound M2Ti (perhaps Ni2Ti) were observed apparently, besides carbides M6C and M23C6.
The procedures described were developed to provide a method for determination of the phosphorus in steel that is free from some of disadvantages in the conventional photometric method. Dissolve a 0.1 gram sample in a 200ml Erlenmyer flask with 3ml of nitric acid (1 to 1) and 5ml of perchloric acid (60%). Evaporate to fumes and then fume for approximately 2 minutes, cool, add 60ml of water, and 0.5 gram of sodium sulfite, heat to boiling, and cool to 10 to 20°C. Precipitate the iron by the dropwise addition of ammonium hydroxide (1 to 1), and add 8ml of sulfuric acid (1 to 5). Transfer to a 100ml volumetric flask, add 5ml of ammonium molybdate solution (5%). After 1 to 2 minutes, add 10ml of sodium fluoride solution (5%) and 0.05ml of stannous chloride solution (10%). Dilute to the mark and mix. Measur the transmittancy against water at 660mμ.