Strain-tempering treatment was applied to variously cold-rolled Fe-Ni (50%) sheets under various conditions and the effect of strain-tempering on the recrystallization texture and grain size was studied. The results obtained were as follows: (1) Grain growth has been easily induced by strain-tempering treatment, and the maximum grain size was influenced by temperature and stress in this treatment. (2) The recrystallization texture by this treatment has become sharper compared with that by ordinary annealing treatment. (3) It was found that the secondary recrystallization was hastened by this treatment and it began at about 1050° in hydrogen gas. (4) The effect of atomosphere on grain growth was studied by using hydrogen, nitrogen and air. We obtained the result that H2 gas was most effective for recrystallization and grain growth.
The SUMP method, which is ordinarily used for optical microscopy, was applied to electron microscopy. This procedure is done as follows the time necesary for preparation is about 1.5 hr. (1) Preparation of SUMP replica (first replica). (2) Evaporation of SiO2, carbon or metals and shadowing. (3) The evaporated surface is coated with paraffin. (4) Dissolving of the first replica and removal of paraffin. (5) Cleaning of the evaporated membrane (second replica). The shape limitation factor of this replica given by Tsuchikura(6) is (This article is not displayable. Please see full text pdf.) \
oindentwhere, dRep. is the resolution of the replica (9.4 mμ in the mean) and dEl. is the resolution of the specimen itself (3.5 mμ in the mean).
In this paper the effects of degree of reduction by cold-drawing and annealing temperature on the fatigue strength of Tough pitch copper, Albrac (patented special aluminum brass) and Admiralty alloys at 10,000,000 cycles were studied on rotating-beam fatigue tester. The following results were obtained: (1) The fatigue strength of Tough pitch copper increases with the degree of reduction by cold drawing. (2) The fatigue strength of Albrac alloy increases with degree of reduction up to 20 per cent by cold-drawing and then decreases with further degree of reduction by cold-drawing. (3) On the effect of annealing of 36 per cent cold-drawn Tough pitch copper, the fatigue strength is not affected up to the recrystallization temperature and decreases over the recrystallization temperature. The S-N curves at each annealing temperature are shown in Fig. 5. (4) In the case of 28 per cent cold-drawn Albrac and Admiralty alloys, the fatigue strength increases with the annealing temperature to recrystallization and then decreases with over recrystallization temperature. The maximum values of fatigue strength of these alloys are obtained at about recrystallization temperature. The slopes of S-N curves of the alloys vary with the annealing temperature as shown in Fig. 7 and 8.
The behaviour of retained austenite in hardened high-carbon high-chromium steel containing 2.17% carbon and 12.57% chromium, has been studied by means of micro-structure, hardness measurement and magnetic analysis. And then the isothermal transformation diagrams of this steel at two maximum heating temperatures were determined. These results are summarized as follows: (1) From 10% to nearly 100% of retained austenite is contained at room temperature in the specimens oil-quenched from various temperatures between 900° and 1200°. (2) The quenching temperature has a large effect on Ms point, and this point is below the room temperature when the quenching temperature is higher than 1150°. (3) The retained austenite in specimens oil-quenched from below 1100° decomposes into bainite or pearlite during subsequent heating at two temperatures, about 200 and 600°, but that formed at the quenching temperature above 1150° decomposes only into pearlite at about 600°. (4) As the tempering time at 550° is longer, the temperature, at which the retained austenite begins to transform during cooling from the tempering temperature, becomes higher. (5) As shown in the isothermal transformation diagrams (Fig. 8), austenite is meta-stable in the intermediate zone.
In succession to our 18th and 19th Reports, the present investigation has been carried out to ascertain the effect of arsenic and copper on strain-aging in low carbon steels, and it was found that the solid solubility of nitrogen in α-Fe was reduced by addition of arsenic and copper: accordingly the strain-aging due to nitrogen decreased, but the strain-aging mainly due to carbon was increased by the addition of arsenic and copper.
The addition of very small amount of boron as little as 0.003% to magnet steel containing 13∼15% of maganese improves the maximum energy product of the steel to about 500 from 400×103 gauss-oersted, while the coercive force or the residual induction were scarcely improved. The added amount of boron to the order of 0.05% is not desirable, because it raised the austenitizing temperature for dissolving the boride and did not improve it so much as compared with the cases of boron added by 0.03%.
The addition of boron to manganese magnet-steels containing 12∼14% Mn produces good results and the best effect appears in steel containing comparatively small amount of Mn, say, 12%. That is, manganese steel containing 12% Mn without having any kind of good properties for magnet, becomes to have the same properties as steels containing 13∼14% of Mn by adding such a very small amount of boron as 0.003%. Moreover, when the specimens were rolled into thin-sheets instead of rolling into the square blocks, rod or wire, the addition of boron produces even better results, that is, the coersive force and the residual magnetic induction are increased considerably. The addition of Ni (1.0∼3.0%) or Cr (3.0%) to “Fe-Mn” magnet steel containing 13% Mn and 0.003% B is not profitable for improving its magnetic properties.
In order to trace the possible cause of influence of extraneous elements, different quantities of Zn, Si, Sn, Mn and Cu were added to Al-Mg alloy and Zn, Si, Mn, Fe and Mg to Al-Cu alloy separately to check the variation in the ratio of the analysing line pair (ΔS) and the ratio of the fixing line pair (ΔSG) in binary and ternary systems. As the result, it has been confirmed that there are some cases when such an influence is experienced and also other cases when such an influence is not experienced. Also, in this study, the influence of the change in the pre-sparking time and the excitation condition has been studied and when a longer pre-sparking time is used, the influence has been decreased. When O. Feussner Spark Generator was used in the case of C=3000 cm, no remarkable difference was noticed between L=0.08 mH and 0.8 mH. The elements which affect the quantitative determination of Mg were Zn, Si and Cu and the elements which affect that of Cu were Zn, Sn, Mn and Mg. When the influence of extraneous elements was not noticed in ΔSG, then ΔS was not affected, either. Using an excitation apparatus which makes it possible to spark to an alloy in molten state, we checked the above solid metals which showed an influence of extraneous elements, but no such an influence was recognized in the case of molten state, thus it was confirmed that the influence by extraneous elements is a phenomenon which is caused by the surface condition of the electrodes.
In Report 3, it was confirmed that the influence of extraneous elements had been caused by the surface condition of electrodes and in this report the influence on vaporization and excitation by surface condition of electrodes has been studied using binary system alloys. Various alloys of binary system such as Al-Zn, Al-Ag etc. have been made and the variation in the ratio of analysing the line pair (ΔS) and the ratio of the fixing line pair (ΔSG) when photographed using the same excitation condition was studied. As the result, when elements are in solid solution with the main element, for instance in the case of Al-Zn and Al-Ag alloys, the element concentration in the spark gap decreases and, at the same time, ΔSG changes and the discharge becomes spark-like. Also, in the case melting point of the electrode surface is lowered by adding various elements, for instance when Sn is added to Al, ΔSG changes and the discharge becomes arc-like. However, the metal compound itself did not show any specific change by sparking. In connection with the above study, various metals were used as counter-electrodes against pure metals and were sparked to check if there is any influence by the characteristics of counter-electrodes on the value of ΔSG. As the result, it has been recognized that the sparking becomes arc-like when a metal of low melting point was used as the counter-electrode.
Experiments described in this paper were designed to investigate the relation between the cell-formation and the initial crystal orientations. Single Al-crystals with various orientations were subjected to creep at higher temperature (500∼550°) under the constant stress nearly equal to the critical shear stress. It was found that the cell boundaries are formed conspicuously only in crystals oriented to the side of 〈100-111〉 and of 〈100-110〉 of the stereographic triangle. The results are discussed in terms of theories of polygonization and cell-formation put forward by Cahn and by Wood respectively. The authors would support the theory of polygonization by Cahn, because the traces of most of the cell boundaries coincide with the main slip bands and the kink bands.
The characteristics of metals and alloys solidified under the hydrostatic pressure of about 1800 kg/cm2 were studied by using the apparatus as shown in Fig. 1. The results were as follows: (1) When 99.9% Sn was solidified under various hydrostatic pressures, the subgrains became finer and were regularly arranged in a certain direction as shown in Fig. 2, and while the grains became larger with increasing pressure. (2) When 62% Sn-Pb and 25% Sn-Pb alloys were solidified under various pressures, the structure of primary solid solution and the eutectic structure both became fine and showed the same structural arrangement as pure tin. (3) The grains and their subgrains of tin samples to which pressure was applied from its melting point up to 229° and up to 200° became larger by successive heating. (4) At constant temperature, the higher the pressure is, the greater the subgrain and the faster the rate of the growth. (5) In these growth processes, the small new grains which originate from the subgrains produced within the grains froze under hydrostatic pressure with heating, and grain growth occurred in successive heating. (6) This growth is strongly affected by the fact that the grains in these specimens have subgrain boundary energy owing to the high hydrostatic pressure.
The coercive force gradually increases as the temperature becomes lower than 730°, and suddenly increases when the temperature comes down to 550°. The remanent magnetization curve follows almost the same pattern as the coercive force-quenching temperature curve. In the magnetic analysis, the saturation-magnetization-temperature curve shows two distinct breaks at 550° and 730°, this curve being reversible both in heating and in cooling. The influence of field cooling is not effective when the specimen is cooled under a magnetic field from 500° down to 200°, but is effective when cooled from 570° to 200°.
The thermo-electro-motive force was measured on some cold worked Cu-Zn and Cu-Al alloys, and the following results were obtained: (1) The thermo-electro-motive force of cold worked-specimens is strongly affected by the working structure, which has macroscopic orientation due to the anisotropic arrangement of solute atoms or lattice defects. The thermo-electro-motive force changes in accorrdance with the concentration of solute atoms and the degree and kind of cold-working. (2) The decrease of the thermo-electro-motive force takes place in two stages in the temperature range of anneal-hardening. But it is presumed that the cause of this decrease is not the same as that of anneal-hardening.
The grain boundary reaction phenomena were studied microscopically on Al-Zn alloys containing 10, 25% Zn respectively, which were solution heat-treated and aged at 70°, 85°, 95°, 120° and 160°. The rate of the growth of nodules which are characteristic of the grain boundary reaction was obtained from the estimation of the measured area of the total nodules. The micro-hardness of the interior of grains and nodules were measured, and the characteristics of the reaction were investigated. The results obtained were as follows: (1) The grain boundary reaction is observed in all alloys we prepared. (2) All the matrices of the alloys are not completely substituted by nodules in the reaction. (3) The total area changed by the nodules which is represented by the fraction of the reacted area to the initial one, changes with the temperature of aging, and it rises to the maximum value at a certain intermediate temperature. That is, when the temperature of aging is too high, the reaction does not occur. (4) Cold working accerelates the reaction. (5) The nodules which contain precipitates perpendicularly oriented to the boundary grow anomalously large. (6) On aging, the micro-hardness of the interior of the grains decreases, while that of the nodules does not change initially but decreases later from the coalescence of precipitates. (7) The grain boundary reaction is also observed at the boundaries of specimens which were furnace-cooled from the solid-solution temperature.