This paper presents the results of investigations of the effect of room temperature annealing upon the internal friction introduced by cold-working versus the cold-working levels relationship of commercially pure aluminium, by means of transverse vibration about 2000 c.p.s. of squars rods. The internal friction versus the cold-working levels curve for the specimens, annealed for about 30 minutes at room temperature, (11°±2°C), before measurement, produced anomalous peaks at around 15 and 55 pct. reductions, respectively. Although the internal friction introduced by cold-working was diminished with annealing time over the entire range of reduction area, the diminution of internal friction was markedly different by the cold-working levels. The first high peak swaged down with annealing time at room temperature and was decayed completely after an annealing for 2\frac12 days at room temperature. The second small peak was not decayed by a room temperature annealing for 41 days. The removal of the internal friction introduced by cold-working for the 15 pct. reduction area followed the (time)2⁄3 law, but in the other specimens it did not followed the (time)2⁄3 law. These observed results were qualitatively discussed.
The purpose of this paper is to report on a study of the effect of annealing processes on the room-temperature internal friction of cold-worked commercially pure aluminium. Since we considered that the measurements of the room-temperature internal friction after repeated higher temperature annealing might be a useful tool for the study of the mechanisms of annealing processes in terms of elementary atomic processes. We have carried out the present study. The effect of the temperature of repeated annealing, say, 13° to 600°C, upon the room-temperature internal friction of 65.4% reduced commercial aluminium was observed by the transverse vibration of about 2,000 c.p.s. From the present results it was revealed that in general trend the internal friction changed along the room-temperature annealing versus the annealing-temperature curves consisting of the first descending part attributable to the segregating process by which the impurity atoms segregate round the first dislocation line by the stress-induced diffusion in about the 13° to 120°C range, the first rising part attributable to the recovery process in about the 120° to 150°C range,the second rising part attributable to the composite process of a primary nucleation followed by polygonization in about the 150° to 270°C range, the second descending part attributable to the homogeneous coarsening process in about the 270° to 500°C range, and the third rising part attributable to an unknown process in which the behavior could not be clearly determined in this experiment, in the range 500°C or higher.
Al and Cu foils down to 0. 005 mm thickness cold-rolled by Sendzimir Mill (ZR 32-4) were examined. The rolling and annealing textures were the same as have been previously reported. In very thin foils, the size of primary recrystallized grains was not affected by the reduction but affected by the thickness, so that the thinner the foils, the smaller the grain size. A two-dimensional grain growth occurred and the grain size/thickness ratio increased with decrease of the thickness. A secondary recrystallization occurred above a certain limit of reduction but did not occur when the foil was thinner beyond a certain limit.
The electrical conductivity of the MnO-CaO-SiO2-Al2O3 system at the composition range 5∼25%MnO and 0.78∼1.43CaO/SiO2 was measured, and the following results were obtained. (1) The specific conductivity “κ” of the 6%Al2O3 samples is 0.1∼0.36 Ω−1·cm−1 at 1,400°C. It increases with a rise of temperature, and at the same basicity, increases with the ratio of the MnO content. When the content of MnO is constant, the conductivity increases with CaO/SiO2, but when this ratio, i.e. the basicity, is above 1.12, it decreases with the increase of CaO/SiO2. (2) From the results at 6%Al2O3 constant, the isoelectrical conductivity lines were plotted on the diagram of CaO-MnO-SiO2 system. (3) Within the range of Al2O3: 1.5∼15%, “κ” tends to attain the largest value at 6∼10%Al2O3. (4) From the relation between logκ and 1⁄T, it was confirmed that the conduction is ionic, and the activation energy was calculated.
The frequency vs. tem perature relation of the vibrators made of Co-elinvar alloy (Fe-Co-Cr-Ni alloy) of various compositions was observed over the temperature range from about 10° to 70°, The measurement was made by comparing the oscillation frequencies of the oscillator stab lized with mechanical resonant vibrators made of the alloy under test with the 1,000 cycle per second standard signal broadcast from the station JJY as standard. It was found that the Co-elinvar alloy, in the region of 34∼38%Co, 5∼11%Cr, 16%Ni and Fe the balance has the frequency temperature coefficient of the order from about 10−5 to 10−6. To test the possibility of mass production of the Co-elinvar alloy, measurement was also made of the frequency temperature coefficient of the vibrators machined from several ingots of the alloy, 34.5%Co, 10.83%Cr, 16.7%Ni,Fe the balance in charge percent, melted in different charge amounts. The frequency temperature coefficients ranging from −3.7×10−6 to +7.5×10−6 were obtained. This result indicates that the Co-elinvar alloy having a very small frequency-temperature coefficient can be produced on mass production scale. The Co-elinvar alloys of the above mentioned compositions are we believe, suitable for constant-frequency mechanical vibrators, high-frequency mechanical filter elements and special springs used in some precision apparatus.
According to my studies on the yielding phenomenon (by tensile tests) of cold drawn austenitic stainless steel wires by using a wire resistance strain meter, the following results were obtained. (1) In steel wires annealed at the temperature of 250° or 350°C after cold drawing, negative (compressive) residual strains appeared when a stress below the yield point was applied and then removed (In these cases, the yield point was defined as the stress above which the residual strain continued to increase toward the positive direction). The mechanism of this phenomenon was discussed from the stand-point of dislocation theory as following: The dislocations which were piled up by the barrier during the cold-drawing, return toward the F-R source when unloaded by the help of kinetic energy obtained during unloading. Therefore the negative residual strains appear. (2) The length of F-R source of an austenitic stainless steel wire was about 10−6 cm, when it was cold drawn by about 40%.
The author carried on tension tests of 99.7%Al foils, hard and soft, at various temperatures between room temperature and 600°C and obtained the following results. (1) The tensile strength of hard foils was decreased along a second order curve with the increase of test temperature and at 300∼400° reached the same strength as soft foils, but the elongation did not recover until it recrystallized around 300°C,as given in the previous report. (2) On the other hand, the tensile strength of soft foils was decreased along a straight line with the increase of test temperature. (3) Near the fracture point, it was observed through a microscope that the foil was deformed by slips at lower temperature and mainly by mutual movement of individual crystal grains at higher temperature as in Al plates. (4) Often it was observed that the thinner the foil the more micro-cracks due to various faults of the surface were formed.
The change in elasticity with rolling reduction of 70/30 brass was measured in three directions of the rolled plate, namely, parallel, diagonal and transverse to the rolling direction. The whole reduction range up to 90% was divided into three stages by the types of the anisotropy. At the low reduction range up to about 40%, the parallel direction showed the maximum elasticity value of the three directions, showing a peak value at the reduction of 20∼30%. This change was thought to be due to a geometrical inhomogeneity of strain distribution found especially in a coarse-grained material at the grain boundaries or at the band-shape regions existing along the rolling direction, rather than to a crystallographic directionality. At the high reduction range beyond about 70%, the developments of the rolling texture and flaw-like strain markings produce a high elasticity value in the transverse direction, and a low one in the others. The intermediate reduction range probably represents a transitional stage between the two shown above. The abnormal work-hardening, previously pointed out by others, was also discussed in relation to the results of the experiment.
A new volumetric method for the determination of small amount of iron in titanium metal is described. The iron (III) is separated from all commonly occurring interfering ions by precipitation with acridine and ammonium sulphocyanide. The precipitate is dissolved in acetone, and then determined volumetrically by EDTA titration method. The procedure is simple, rapid, and is more accurate than any method reported in the past literature.
A series of experiments were carried out about the corrosion-fatigue properties in a 3%NaCl aq. solution and the notched-fatigue properties (theoretical stress concentration 3.15) of some annealed brasses and condenser tube alloys with a rotating-beam fatigue tester. The effects of aluminum contents on the fatigue properties of aluminum brass were also studied with a Schenck’s plane-bending fatigue tester. The relations between the fatigue strength at 108 cycles and zinc or zinc equivalents of the specimens are shown in Fig. 6. The increases of zinc or zinc equivalents improve the mechanical properties and the unnotched-fatigue strength in air, but excessive increments of these contents will not effect any improvement on the corrosion-fatigue and the notched-fatigue resistances. The corrosion-fatigue strength of copper-zinc binary alloy increases with zinc contents and then decreases with a rise over 20 per cent of zinc contents. In the case of aluminum brass, Albrac alloy, Admiralty metal and arsenical Admiralty metal, the materials with rich zinc equivalent contents showed lower notched-fatigue and corrosion-fatigue strengths than that the materials poor in zinc equivalent contents. These results show that the corrosion-fatigue strength is related to the notched-fatigue strength.
Many papers concerning the sampling method for gas analysis in iron and steel have been published, but no decisive method has been established. We studied the sampling methods of specimens for gas analysis from refined melts. That is, we studied the segregation of gases and the relation of the micro-structure to the gas content in the specimens when they are cast in various moulds. The results were as follws: (1) The least segregation was obtained when the specimen was cast in a 6 mmφ steel mould. (2) The oxygen content of a specimen cast in dry sand mould was larger than in a specimen cast in a 6 mmφ steel mould. That is,the oxygen content is increased when the cooling rate is small. (3) There were small differences between the gas contents in steel-mould specimens and in graphite-mould specimens, but we noticed no change of gas contents even when the micro-structure was changed. (4) Determination of hydrogen in iron and steel must be executed as rapidly as possible, because hydrogen diffuses out easily. (5) There was no difference between the analytical value of hydrogen in polished and in unpolished iron or steel specimens. In this case a reliable analytical value of the nitrogen content can be obtained. (6) The hydrogen content in a specimen kept in liquid oxygen does not change for two weeks at least.
M23C6 in tungsten steel is a metastable carbide, which decomposes into other carbides during long annealing. Honda and Murakami already mentioned this phenomenon, and studied its characteristics by thermo-magnetic method. In the present investigation, the decomposition processes of M23C6 during subcritical annealing were studied by electrolytic isolation, subsequent X-ray analysis and electron-microscopic observation methods. The mechanism of the decomposition of M23C3 is not simple, but includes two different carbide reactions; (i) M23C6→M6C (ii) M23C6→WC. The addition of Si and Ti to tungsten steel accelerates the reaction (i), and that of Co and Ni the reaction (ii), while Cr, Mo and V have the effect of retarding the decomposition of M23C6. The so-called “Spoiling” in tungsten magnet steels, which has been explained by WC formation from M6C, should be considered as produced by the decomposition of M23C6.
The electrical conductivity of molten slags of high titanium content and of various FeO contents was measured by the four-terminal method. The measured range of temperature was 1450∼1200°. The specific electrical conductivity is 5∼12 Ω−1 cm−1, which is very high as compared with the ordinary slags of pig-iron making. In molten state the conductivity decreases with temperature, but in the neighbourhood of the solidifying temperature two sorts of anomalous changes appear. The minimum conductivity value was found to lie at the composition of 23 pct FeO, which coincides with the composition dividing the composition range into two parts according to the sorts of the above-mentioned anomalous changes. The electronic conduction in terms of valency exchange may be predominant in the present system. The conductivity data and the mechanism of conduction have great significances in the design and the practical operation of an electric furnace making high titanium slag.
Iron sheets clothed by aluminium, copper and brass were cold-rolled to a reduction in thickness about 90%, and the textures of the clothing metals have been examined by the X-ray photographic method. The rolling texture of Al-clad iron sheets can be described as (001) orientation. The principal orientation in rolled Cu-clad sheets is also described as (001) accompanied by minor components having the orientation (110)[1\bar12] and (112)[11\bar1], while the rolling texture of brass-clad sheets can be written as (110)[1\bar12]. The orientation of the type (001) in the surface of Al sheets has been reported by G. Wassermann. From those experimental results, it can be concluded that the rolling texture of clothing metals is in conformity with the surface texture of cold-rolled block metals in general.
The reaction kinetics of the Kroll-processed reactor-grade zirconium under 1 atm. of air was studied over the temperature range of 650° to 900°C. An analysis of the rate data showed that the cubic rate law was applisable in the initial stage of oxidation. However, a breakdown of the oxide film was observed at 800° and 850°, and then, the oxidation proceeded in accordance with the linear rate law. A plot of the logarithms of the cubic rate law constants against the reciprocal of absolute temperature gave a straight line and the activation energy of 48,400 cal/mol was calculated. Chemical analysis was used for the determination of the amount of nitrogen absorbed during oxidation of zirconium in air. The contents of absorbed nitrogen in the oxide layer increased with oxidation time and temperature, but no existence of a ZrN phase was found by X-ray analysis. The experimental formula of absorption of nitrogen during the oxidation of zirconium in air, W3⁄2=kt (where W: Weight of absorbed nitrogen, k: constant, t: time), is suggested. And the activation energy of 82,400 cal/mol was calculated for absorption of nitrogen during the reaction of zirconium with air, over the temperature range of 700° to 850°. In these consideration, the authors came to the conclusion that the rate-controlling step of the oxidation of zirconium is the process of diffusion of oxygen ion in the oxide film.