The behavior of residual micro-stress caused in carbon steel by phase transformation during heat treatment was studied in the processes of aging and fatigue by observing the change of X-ray back reflection patterns. The half-value breadth was taken as the measure of micro-stress. Steel wire of 3 mm diameter and 0.78% carbon content was used for the material of specimens. Thes pecimens were prepared by quenching from 850°C with subsequent tempering at the temperatures of 100°, 300°, 500° and 800°C for half an hour each. The results obtained summerized as follows: (1) The phase transformation micro-stress diminishes markedly by heating, even at comparatively low temperature such as 300°C. (2) The micro-stress diminishes by aging, in accelerated rate during the first ten days and then gradually. (3) The material tempered at 500°C still contains a noticeable amount of micro-stress. When the material is subjected to stress alternation, the micro-stress tends to fade, in accelerated rate during the first 104 stress cycles and then gradually. It is likely that the micro-stress reaches a definite value just before fracture of the material, irrespective of the magnitude of alternating stress applied. (4) The relation between b⁄B and logn⁄N, where b and B are the current and the initial values of the breadth and n and N are the current and the ultimate numbers of stress alternation, is represented by a straight line, irrespective of the magnitude of alternating stress applied. This relation offers possibility of the non-destructive detection of fatigue damage. (5) In the case of the material tempered at the temperature lower than 100°C the micro-stress tends to increase at the early period of stress alternation and then decreases in a similar manner to the case of 3). It may be due to the transformation of residual austenite to martensite.
The effect of prior heat treatments on sigma transformation of high chromium steels which contained 35∼60% chromium, was investigated by hardness, intensity of magnetization and microstructure. The prior heat treatments were of the following three kinds: (1) Annealing at 500° for 500 hours, (2) furnace cooling from 1000° and (3) water quenching from 900°. Annealing temperatures were 650°, 700° and 750° and annealing time was up to 300 hours. In general, the rate of sigma transformation of the specimens heat-treated as (1) was most rapid, and that of specimen heat treated as (3) was slowest. The reason of this difference was not ascertained, but the nuclei of sigma phase which resulted in annealing at 500° for 500 hours seemed to play an important roll.
Using a specimen cyanided at 780°C for 15 hrs and having a comparatively thick outer layer, the qualities of the layer were mainly investigated. It was confirmed that the outer layer consists of a compound layer and a composite layer contained compound and solid solution. It was clarified that the partial extinction in the cementite diffraction patterns is due to existence of martensite, and definition of the term “outer layer” was given. Also, the carbo-nitriding diagram of this case was decided, and the correlation of the diagram with the thermal changes of the case was explained.
Investigations has been carried out on the suitability of methanolic cupric chloride solution for solution of only the metallic iron fractions in a reduced manganese ore which contains ferro manganese fractions other than oxides of various grades of iron and manganese, and the possible interference of the cupric ions present in the resultant iron solution in the permanganate titration. A sample of to 0.20 g was treated with 50 mL of methanol containing 5 g of cupric chloride and 0.4 g of sodium carbonate at 40°C for an hour, cooled and filtered, then the mixture of the filtrate and the washings is made up to 0.1 N sulfuric acid solution and heated till colorless after addition of 0.3 g of metallic aluminum, and again filtered. The iron determined by means of permanganate titration in the filtrate represents the metallic fraction of the reduced manganese ore and ferro-manganese.
The residue from the treatment of reduced manganese ore with methanolic cupric chloride solution, in the previous report, includes various oxides of manganese and iron. In this study a fractional method of determination of manganese monoxide in the above residue is investigated. As the result of experiments, the treatment of the residue by adding 20 mL of 6 N ammonium-sulfate solution and heating in a boiling-water bath for approximately 30 min in CO2 stream was decided as a suitable method of dissolving manganese monoxide only with nearly none of the other oxides being brought into the solution. After filtering the solution, the manganese in the combined solution of the filtrate and the washing is determined titrimetrically as manganese monoxide fraction of the residue by means of persulfate ferrous-permanganate method.
The principal emphasis in this research has been placed on determining what the effects of the melting-furnace atmospheres on graphitization are. Two kinds of white iron were employed as raw material for melting. One was commercial white iron, the other was synthetic white iron made from electrolytic iron, electrode graphite and metallic silicon. The melt of white iron was held at 1320∼1330°C for 30 min in vacuum or an atmosphere of gas such as argon, nitrogen, after holding in vacuum for 60 min, and was cast in an iron mold. Melting in vacuum tends to decrease the amounts of gaseous elements. From the results obtained, it is concluded that the effect of the melting-furnace atmosphere on the graphitization is related to the change in the acid-soluble nitrogen content. In this experiment, however, the difference of melting-furnace atmosphere caused no appreciable change in the chemical components but nitrogen. If the amount of the elements except nitrogen was varied by differing furnace atmospheres, the graphitization would not be affected by the amount of acid-soluble nitrogen alone.
Practical problems concerning the application of proposed spectrochemical method to routine industrial analysis were studied. (1) The loss of impurity Sn in the course of dissolution of sample Zn in HC1 and of the subsequent concentration of the dilute ZnCl2 solution to 1.95 in specific gravity is prevented by small addition of H3PO4. (2) The allowable range of specific gravity in preparation of sample solution is 1.98∼1.93, in which the variation of ZnCl2 concentration does not affect the analytical precision and accuracy. (3) The procedures of background correction,proposed in ASTM E116-56T, were studied and simplified by using the galvanometer deflection, instead of optical density or Seidel function. (4) Spectrochemical sensitivities of 13 elements in ZnCl2 70% solution,which are presented in Table 3, were studied under the previously proposed conditions. (5) Some analytical results of commercial high purity Zn, are shown in Table 4 as practical example of this spectrochemical analysis.
During the oxidizing process in steel-making, it is very difficult to take a suitable sample, beause a large amount of gases, especially oxygen is dissolved in molten steel. This paper gives a new sampling method for determination of gaseous elements in steel. A spoonful of molten steel is taken up with a ladle coated with slag and killed with 1% of aluminum wire against the molten steel. Then molten steel is sucked up from the ladle with a silica tube of 6 mm inner diameter. The results obtained are as follows: (1) The gaseous contents in molten steel are duly represented in the sample. (2) Segregation of gaseous elements in the sample is very limited. (3) Machining and holding the sample is easy. (4) The method is less expensive than any other methods.
In determining aluminum and sulfur in ferro-molybdenum, iron and molybdenum were removed by using methyl-isobutyl ketone extraction method. After the removal of iron and molybdenum, aluminum was determined gravimetrically or volumetrically by using oxine, by which 0.1∼1 per cent aluminum in ferro-molybdenum was determined. By using methyl-iso-butyl keton for ether, the danger of explosion caused by organic vapour and the disturbance of molybdenum were avoided. Sulfur was determined gravimetrically as barium sulfate down to 0.005 per cent content of it. The present procedure is superior in its simplicity and in being free of the obstruction by molybdenum trioxide to the usual combustion method for sulfur.
We studied the Hall effect of InSb and its practical application as a flux-meter. The direction of leakage flux density of permanent magnets of various shapes, and obtained the data concerning the influence of magnetizing method on the distribution of magnetic density, the orientation of maximum leakage flux density, the influence of iron yoke on the distribution of flux density, and so on.
The present authors made observation on oxide films and scales produced on the surface layers of Fe-Si-Cr system alloys (ca. 1∼7%Si, 5∼19%Cr), when they came into contact with air at high temperatures (700∼1200°C) using the transmission electron diffraction, X-ray diffraction and a metallurgical microscope. Thereby the authors verified that ca. 3∼7%Si-Cr-Fe system alloys are covered mainly with Cr2O3 or α-(Cr,Fe)2O3 crystal films in the earliest stage of oxidation at 700° and 1000°C (Table 1). The authors have already reported that amorphous SiO2 films were detected on the surfaces of ca. 1∼6%Si-Fe system alloys at 700∼1000°C oxidation, but this kind of oxide films has not been observed on the surfaces of ca. 1∼4%Si-Cr-Fe system alloys heated in air under the same conditions. The present studies also clarified experimentally that the heat-resisting films of Fe-Si-Cr system alloys oxidized in air at 1100° and 1200°C for 7 hrs are composed of fine Cr2O3 crystals (Table 1).
The effect of dissolved sulphur on the surface tension of liquid copper has been measured by the sessile drop method at 1114°, 1200°, 1300° and 1340°C. Sulphur is highly “surface active” in liquid copper, and at a sulphur content of 0.6%, the surface tension is lowered by about 620 dyn·cm−1 at 1114°, 580 dyn·cm−1 at 1200°, 530 dyn·cm−1 at 1300° and 470 dyn·cm−1 at 1340°C, respectively. The degree of adsorption of sulphur on the liquid copper surface has been calculated and the result indicates that the maximum surface excess of sulphur is about 1.6×10−9 mol·cm−2, which corresponds to a mono-molecular layer of Cu2S or S−−.
The effect of dissolved oxygen on the surface tension of liquid copper has been measured by the sessile drop method at 1115°, 1230° and 1300°C. Oxygen is highly surface-active in liquid copper, and for a oxygen content of 0.2%, the surface-tension is lowered by 450 dyn·cm−1 at 1150° 420 dyn·cm−1 at 1230° and 380 dyn·cm−1 at 1300°C. The degree of adsorption of oxygen on the liquid copper surface has been calculated, and the result indicates the maximum surface excess of oxygen to be about 1.0×10−9 mol·cm−2, which corresponds to a mono-molecular layer of Cu2O or O−−.
The galvanic corrosion of commercially pure titanium coupled with 18-8 stainless steel was studied in various kinds of corrosive media. In reducing, acids, although the corrosion potential of titanium itself was in the active range and less noble than that of stainless steel, it was shifted into the passive range by coupling with stainless steel. Thus, titanium was anodically protected and its corrosion rate decreased remarkably, whereas the corrosion rate of stainless steel remained unchanged. For instance, titanium and stainless steel was perfectly resistant in 10% hydrochloric acid, 10% sulphuric acid and 10% oxalic acid solutions at room temperature, in which uncoupled titanium was corroded. This phenomenon of anodic protection was also observed in boiling 1% hydrochloric acid, 1% sulphuric acid and 0.5% oxalic acid solutions. In oxidizing acids, such as nitric acid, the galvanic corrosion was negligible, because the potentials of titanium and stainless steel were in their own passive ranges, and that of the couple was also in the passive range of both metals. In the case of boiling 99% acetic acid no galvanic corrosion was observed, either. In neutral chloride solutions, such as 3% sodium chloride solution, the potential of couple fluctuated and the direction of galvanic current changed irregularly because of the instability of protective film on stainless steel. However, the galvanic current was always less than 1 μA/cm2, so that the galvanic corrosion was also negligible.
In order to extend the new definition of basicity, which the author has recenly proposed taking the well-known fact that the ferrous and ferric concentrations in a slag change regularly with the basicity, to any generalized slag system, the following expression of slag basicity was given. BL=∑\limitsiaiNi (Ni-mol fraction of the constituent, ai-constant characteristic of the constituent). The values of the constants ai are shown in Table 1. Several applications of this new expression of slag basicity were illustrated, and the significances of basicity in the iron and steel making reactions was clarified. The applied examples are as follows: (1) Solubility of magnesia in the CaO-SiO2-FeO-MgO slag. (2) Sulphur capacity of slags. (3) Desulphurizing reaction between blast furnace slags and metal. (4) Partition equilibrium of sulphur between basic slags and metals. (5) Reduction of titanium and silicon from slags containing titanium-oxide. (6) Desulphurizing power of slags containing titanium-oxide. (7) Reduction of silicon from flux into deposited metal in welding.
Metallographic examination, micro-hardness measurement, and observation of specific heat vs. temperature curve were performed for studing the aging process of lead alloys containing 1, 2 and 3 wt%Sb at room temperature. (1) The change of the metallographic structure took place with aging time (t) in two stage. The first stage was of “continuous precipitation” type, and the second stage was of “discontinuous precipitation” type. It was found that the discontinuous precipitation observed was accompanied by grain-boundary migration. (2) The increase of hardness (H) could be related with the continuous precipitation. (3) The heat of re-solution ([P]) of the stable precipitates produced at room temperature prior to testing the specific heat vs. temperature curve,was determined. [P] increased with t in a single stage. The increase of [P] could be also related with the continuous precipitation. (4) The fractional changes (f) of both H and [P] seem to be represented by Johnson-Mehl’s equation; f=1−exp(−btn), where, n is a constant independent of the alloy constitution and has the value of 2.0±0.25.
For the zone refining of indium, tow methods were employed: The one is the ordinary method and the other involves a forced cooling of unmolten parts of the ingot bar by setting up two water-cooled copper tubings on both sides of the zone heater. In both cases, spectrographic and polarographic analyses showed clearly that tin, copper, cadmium, magnesium and thallium segregate at the finishing end of the ingot bar, while lead segregates at the beginning end. The recrystallization structure showed also the effect of purification by the zone refining. A slow rate of zone travelling of 17 mm/hr was more efficient in removing impurities than a faster rate of 69 mm/hr. In comparison of the two methods, the method involving the forced cooling was found preferable in consideration of refining efficiency to the ordinary non-cooling method. The reason may be that the forced cooling of both sides of the molten zone keeps a constant zone length throughout the travelling as well as maintains a higher temperature of the molten zone than in the case of ordinary method so as to give a higher diffusivity of impurities in the zone as a result of a steeper temperature gradient at the liquid-solid interfaces.
Carbides isolated electrolytically from molybdenum steels were studied by X-ray, chemical and thermo-magnetic analyses, and by electron-microscopic observations, with the objects to elucidate the nature of carbides in the steels, and to determine the carbide-phase diagram of molybdenum steel below the eutectoid temperature. In the case of thermal treatment at 700°C for 24 hrs, the carbides formed by tempering are quite different from those formed by isothermal transformation. But, after a prolonged treatment at 700°C, carbides in both the structures tend to approximate each other gradually, and five kinds of carbides, M3C, M23C6, ξ, M2C and M6C appear, as the atomic ratio Mo: C in the steel increases. Among these carbides, M3C and M23C6 are ferromagnetic, of which the Curie points are 215∼181°C and 312∼183°C, respectively. The composition ranges of carbides in molybdenum steels at 700°C are as follows. M3C: 6.67%C, 0∼2.5%Mo; M23C6: 5.0∼6.0%C, 5.5∼13.5%Mo; ξ: 5.5∼6.0%C, 30∼37%Mo; M2C: about 6%C, 70%Mo; M6C: 2.5∼2.8%C, 45∼62%Mo.