The author observed the deformation in various specimens of C 2∼4% white cast-iron and of C 3%, Ni 3.5∼4.5%, Cr 1∼2% alloy white cast-iron, as cast and heat-treated, subjected to bending, compression, hardness, and hammering tests. The results were summarized as follows: (1) When subjected to tensile stress cleavage cracks appeared mainly in the eutectic cementite, and passed through the primary crystals or along the boundaries. (2) When subjected to compression stress, he specimens, having low hardness values were broken along the glide plane 45° to the compressed axes and, near the glide fracture planes, the net-works of eutectic cementite were crushed, but the crushed cementite particles were enveloped by the flow of primary pearlitic crystals. Thus, overall fractures could not easily happen. (3) Slip lines were seen in the eutectic cementite in the compression, hardness and hammering test pieces. The slip lines in the eutectic cementite for chilled specimens were about parallel to the chiller surfaces. (4) Hair cracks often appeared in the eutectic cementite and sometimes in or along the needle-like proeutectoid cementite or the martensite plates. Tempered graphite and Mn-S particles seemd to have no relation to the cracks.
Bending and impact tests were carried out on sand-cast specimens and heat-treated ones of C 2∼4.2% white irons and C 3%, Ni 3.5∼4.5%, Cr 1∼2.5 alloy white irons. The results were as follows: (1) Some hair cracks were found in the eutectic cementite or along the boundaries, on the tension side of the bending test pieces, when the tensile strain became about 0.1∼0.5%. (2) When the cracks reached the primary crystals, they passed as transcrystalline (about 70%), or as intercrystalline cracks (about 30%). (3) As the hardness of the primary crystals or C% of the alloys increased, the flexture decreased from 5 to 1 mm, the fracture stress from 160 to 30 kg/mm2, and the impact value from 30 to 10 kg·cm/cm2. (4) The fracture stress in bending tests varied markedly. The factors causing this variation seemed to be S%, C%, the melting, the casting and the heat-treatment conditions of the alloys.
It is very difficult to measure the longitudinal and radial expansion coefficients of Dumet wires in commercially used forms. It may therefore be useful to construct charts from which the thermal expansion curves are readily drawn if we know the copper ratio as well as the nickel content of the core metal. Using appropriate formulas for calculating expansion coefficients from the basic physical properties of copper and the core metal, we have made 8 such charts and also made 4 charts of mean expansion coefficients in the range of 30°C to 380°C and 0°C to 500°C. By use of these charts we can immediately select Dumet wires suitable to the glass used for manufacturing electric lamps, elctron tubes, etc.
Recently Mischmetall is often used to manufacture high-alloy steels. This technique requires the establishment of adequate methods of chemical analysis for the rare earth elements in iron and steel. In the present paper a method was introduced which is superior in simplicity, rapidity and accuracy than those ever used in this field. In these methods, rare earth elements were isolated from the many coexisting metals by one of the following three methods. (1) The principal constituent, iron, was extracted by methyl-isbutylketone, then the remaining Fe and Cr were separated by electrolysis and next the rare earth elements were separated by precipitation as fluorides. (2) For the sample containing tungsten, the precipitated WO3 was redissolved in ammonia water and adding HF, the rare earth elements were regained as fluorides. (3) The sample was dissolved in perchloric acid and hydrofluoric acid, and the rare earth elements were separated directly as fluorides.
Cerium and La were isolated from the rare earth elements by the previously reported methods and were determined by the following method methods. (a) Cerium was oxidised to Ce++ state and methylene-blue was dded thereupon and after having been extracted with benzene, the absorbancy was measured at 510 mμ (b) The isolated lanthanum oxide was dissolved by sulfuric method atomizing and exciting it by hydrogen-oxygenflame.
Es ist wahrscheinlich, dass die Bildung der porigen Ferrosiliziumschicht auf dem Kirkendallischen Effekt d,h der ungleichmässigen Diffusionserscheinung zwischen Siliziumatom an der Oberflächenschicht und Eisenatom in der inneren Teil zurückzuführen ist. Bei der Silizierungsbehandlung über 1150°C, die von Dr. Fitzer “Sintersilizierung” genannt wurde, wird der Sintervorgang stark erfördert, so wird die Oberflächenschicht von Poren befreit. Je mehr die Zeitdauer für Silizierung verlängert wird umso mehr ist die ungleichmässige Diffusion beschleunigt und neue Porensäume werden in der Schutzschicht wiedergebildet. Wird die Silizierung bei höheren Temperatur und in kurzer Zeit deuchgeführt, so gewinnt man eine porenfreien Schicht. In diesem Fall spielt wahrscheinlich die Verdichtung durch Sinterung eine grösseren Rolle als der Kirkendallische Effekt durch Diffusion. Durch die Silizierung bei 1180°C, 20 Minuten ist es möglich, eine porenfreien Schutzschicht mit 0.3 mm von Dicke an der Oberfläche von Stahl mit 0.4%C zu erreichen.
The investigation was carried out to find the optimum conditions to determine oxygen in metallic chromium by either vacuum fusion method or bromine method. In the vacuum fusion process, oxygen was determined by using iron bath to drop the gas extraction temperature to 2100°. The apparatus used for the bromine method was that used for oxygen determination in titanium metal improved in several parts (bromine bottle and the reaction furnace). The optimum conditions for the determination of oxygen in chromium metal by bromine method are as follows: Bromination temperature 950±25°C Reaction time 1.5 hr; Sample 0.5 g; Graphite carbon 0.5 g; Argon gas flow rate 8 mL/min. The results of the oxygen determinations in electrolytic chromium agreed well in both methods.
17Cr,7Ni stainless steel containing about 1%Al was experimented upon for determining its mechanical properties after heat treatments such as solution treatment, intermediate quenching and aging at various temperatures and hours. The following results were obtained: (1) The Ms point of this steel is in the range of 150∼0° when it is quenched from 750∼1000°. So this steel may be hardened by water quenching. (2) This steel showed better mechanical properties by aging after solution treatment and intermediate quenching. The highest values were obtained under the following aging conditions; 400°×100 hr, 450°×8∼12 hr, 470°×5∼8 hr and 500°×1 hr.(3) The maximum values of mechanical properties were as follows: tensile strength, about 160 kg/mm2; yielding strength (0.2%) about 120 kg/mm2 and elongation 4∼6%.
The author have studied the phase diagram of the system Al-Zn-Mg (especially in the range of Al-Zn side). The diagram obtained by means of inverse rate thermal analysis, electric resistance measurement, X-ray analysis and microscopic observation is shown in Fig. 8. Six non-variant points are observed in this system. (This article is not displayable. Please see full text pdf.)
The present paper describes a specimen-treating adaptor for the electron microscope devised by the author and others. This enables to take micrographs and selected-area diffraction-patterns of one and the same part of the specimen before and after a chemical or physical treatment, so that even minute changes can reliably be detected. The observations are possible with a freshly prepared specimen without exposing it to air and moisture, so that their deteriorating action can be completely eliminated. The detection of minute changes would naturally be impossible, if comparision was to be made, as is usually done, between a few particles taken from a lot of the powder before and after the treatment.
Molybdenum trioxide crystals were mounted on the sharply pointed end of a fine tungsten wire and exposed to heated hydrogen gas under about one atmospheric pressure in the specimen-treating adaptor attached to the electron microscope, previously devised by the author and others, and the morphological and chemical changes in a certain chosen region of the specimen were followed by taking micrographs and selected-area electron-diffraction patterns. Many informations on the formation of molybdenum metal particles were obtained. The mechanism of formation of metallic particles is discussed.
Titanium seems to be suitable for use as anode material of an electrolytic capacitors because of its higher corrosion resistivity than aluminium, its lower cost than tantalum, and the very large dielectric constant of its oxide. However, it is of no practical use due to its appreciable leakage current. An electrolytic capacitor with a titanium-plated aluminium electrode was compared with that with an ordinary aluminium electrode. It was found that the leakage current and the power factor increased, while the increase in capacitance was very small. The large leakage current is characteristic of the oxide film of titanium and is not due to the impurities in titanium. Therefore, inspite of the several excellent properties of titanium for the electrolytic capacitor, the realization of its practical use is a remote possibility.
Thermal contraction in cooling was prevented as a representation of a special thermal stress in the surface layer of steel induced by quenching. The effects of such thermal stress on retained austenite (γR) were as follows. (A) Experiments on high carbon alloy steels. (1) The tensile stress induced by preventing the thermal contraction increased linearly with decreasing temperature and indicated the maximum value at Ms temperature, that was about 10 kg/mm2. (2) The amount of γR was markedly increased by preventing the thermal contraction. This is contrary to the expectation from the mechanism of martensite transformation which has been interpreted from the criterion of shearing stress. (3) The effective temperature range of stress on γR existed between 100∼150°C above Ms point and room temperature. Also the most effective temperature lies in the vicinity of Ms temperature. (4) The rise of cooling velocity at the range of above Ms temperature increased the amount of γR as the result of increment of induced tensile stress. (5) At below Ms temperature, the rise of cooling velocity decreased the amount of γR, similarly to free contraction cooling. Therefore it appears that there is no effect of stress on the thermal stabilization of austenite. (B) Stabilization of austenite by preventing the thermal contraction was not observed in medium and low carbon alloy steels, and in low carbon alloy steel the amount of γR was decreased, contrary to the case with high carbon alloy steels.
Polycrystalline specimens of Al-30 wt%Ag alloy, which were quenched into water from 540°C, were annealed at L.T. aging temperature or reversion temperature so as to make them contain zones of various radii and concentrations. These specimens were cold-rolled exactly to 50%, and then annealed at 150°C for varying time. The state of zones and γ′-precipitates were investigated by X-ray small-angle scattering photographs. The results obtained were as follows: (1) The precipitation of γ′-phase during annealing at 150°C, begins very earlier in these specimens than in the specimens cold-rolled immediately after quenching. (2) The precipitation of γ′-phase begins earlier in the specimens annealed at L.T. aging temperature than in the specimens annealed at reversion temperature. (3) At 150°C the rate of disappearance of zones depends mainly upon their concentration rather than on their radius. The deformed zones of high concentration disappear earlier than the deformed zones of low concentration during the annealing. (4) The deformed, dilute zones become more concentrated before the precipitation of γ′-phase. (5) These results may be explained without contradiction considering that the stacking faults formed by cold working behave as the nuclei of γ′-precipitates.
As one of the studies on the recovery and recrystallization processes of statically and dynamically cold-worked metals, the release of stored energy of statically or impactly compressed commercial aluminium has been measured. Except at small compression, all of the released energy versus temperature curves of both statically and impactly compressed specimens have a shoulder and three peaks respectively, but the forms are different with the compression methods. That is, the higher the peak temperature, the larger the value of the peak under impact compression, but under static compression, the values of peaks under small compressions decrease with the temperature, while the values under large compressions become larger with the temperature. Then the total released energy under static compression is somewhat larger than that under impact compression, but both increase with the degree of compression. On the structure of the comparatively large compressed specimens was found an anisotropic growth of sub-grains by heating up to the second peak temperature and of recrystallized grains by heating up to the third peak. The first peak near 120°C in the released energy curve may be attributed to the extinction of vacancies and interstitials and to the formation of Cottrell’satmosphere of impurities. The second peak is attributed to the sub-grain formation due to the rearrangement of the dislocation forming Cottrell’satmosphere, and the third peak to the recrystallization. These results agree closely with the phenomena found in the room-temperature internal friction change of cold-compressed aluminium by the repeated annealing.
With an electron-microscope, observation was made on the fine lamellae (spacing=150∼300 Å) in the martensite of Kovar using replicas. The results were as follows: (1) Lamellae are hardly seen in the surface relief (the surface is electrolytically polished before transformation), but they are clearly revealed by light etching of that surface. Their form and density are nearly the same as in the case of the surface relief of Fe-Ni alloys. (2) They look to consist of parallel ridges somewhat different from the ordinary deformation slips. They are distributed more densely and more uniformly all over the martensite plate than in the latter case. (3) The appearance of these fine parallel lamellae supports the idea that transformation slip with a fine spacing occurs in the martensite during the transformation.