Lead alloys, with several percent of antimony as well as small amounts of tin and arsenic are in use for the grid of lead acid batteries. Though the alloy is age-hardenable at room temperature, at least 3-days aging is required before the alloy becomes hard enough to be safely treated in pasting operation. For the purpose of reducing the aging time to cut down the period necessary for the production, a method of accelerating the aging has been studied. As the result, only 2 hours were found to be necessary for the alloy to attain the first plateau in the aging curve by heating it at 70°C after casting. The result has been successfully applied to the production process of lead-acid batteries in the author’s plant. The influence of additional elements, 0.05 and 1% each of Ag, Te, Se, Na, Cu, Mg, Cd, Zn, has also been investigated. Among the elements considered, Mg, Ag, Se and Cd have been found to accelerate aging but the effect was found to be less than that of keeping the alloy at 70°C.
Investigations of the effect of the grain size, working, and heat treatment on the creep rupture properties of 18-8 Ti stainless steel tube have been carried out. As the result of 650°C creep rupture tests on the tube material, the following conclusions have been reached. (1) It is generally recognised that, in the case of the tube material having fine grain structure, the creep rupture strength is small and the rupture elongation is large. However, our studies indicate that the grain size has not much bearing upon the creep rupture properties. (2) After working, the creep rupture strength in the short-period side becomes large, but at the long period side, it becomes considerably small and the rupture elongation increases. Such a tendency becomes more pronounced in the case of cold working than in hot working. (3) Heat treatment after working has a great effect upon the creep rupture properties. Just simple annealing for softening makes the creep rupture properties worse than those of the material which was subjected to working only. The material will have the better creep rupture properties by being treated at a temperature whithin the range where the maximum possible amount of C and Ti are dissolved as super-saturated solute elements.
The structural changes in the test pieces of 18-8 Ti stainless steel have been examined to determine the effect of working and heat treatment upon creep rupture properties. The following are the conclusions of this investigation. (1) The creep rupture strength in the long period side is very small when the test pieces are subjected to cold working or heat treatment at a comparatively low temperature before the test. This is partly due to the fine grains formed by recystallization, but is mostly caused by the loss of the precipitation effect which prevents creep deformation due to over-aging accelerated by recrystallization. (2) It makes a great difference in creep rupture properties of 18-8 Ti stainless steel whether the heat treatment after working is made at a comparatively low temperature in the precipitation temperature range, or at a high temperature in the soluble temperature range.
The effects of the deoxidizer on the microscopic structure and the strength of anode Cu ingots for X-ray tubes were investigated. A small amount of Si and CaSi were used as the deoxidizer. A clear dendritic structure which might be attributed to the segregation of minor impurities was observed in the grain by HNO3 etching. The grain boundary of the specimen deoxidized by Si showed a straight form and fractured always at the boundary above 600°C, while the boundary of CaSi-deoxidized specimen showed irregular form and didn’t always fracture at the boundary. From these facts it was presumed that the concentration of impurities at the grain boundary of the former specimen might be higher than that of the latter.
Generally speaking, the properties of magnetic alloys are mainly dependent on the purity. The properties of 50% nickel-iron magnetic alloy are also affected by the quantity of deoxidizers and contained gas. So, the author prepared the subject alloy by vacuum melting to make the impurity i.e., hydrogen, oxygen, manganese etc. decrease and investigated the resulting characteristic properties. As for a 50% nickel-iron magnetic alloy, heavily cold-rolled and having a rectangular hysteresis loop, the coercive force of the vacuum-melted specimen is much smaller than that melted in air. While we looked through the refining time in melting of this alloy, we have found out the fact that the longer was the time, the better were the properties. Collecting four samples of which the refining time were 20(A), 75(B), 180(C), 300(C) minutes respectively, the properties of B and C are not much different but consideravely better than in A. But it is noted that the properties of D are superior to those of the other specimens.
A spectrographic method was studied to determine microamounts of Ca in Mg metal and Mg alloy, and it was found that Ca in Mg could be determined by exciting sample solution in a porous-cup electrode with the transient discharge source unit. The results obtained were as follows: (1) In consideration of the viscosity of Mg solution and the spectral intensity of Ca, 0.5 g of sample was dissolved in HCl and afterwards diluted to 50 mL. (2) The discharge conditions were E(discharge voltage)=200 V, C=18 μF, L=30 μH, and R=2 Ω. (3) Exposure was started after 15-sec preliminary discharge, as the discharge in stabilized with in several seconds after its start. (4) Al, Zn, Mn, Fe and Zr contained in Mg alloys had no influence on tne analytical results of Ca, excepting the case when samples contained about 5% of Zn. (5) Samples containing 0.01 to 0.3% of Ca were analysed with Sr II 4215.52 Å/Ca II 3933.67 Å as the analytical line pair, the reproducibility being 5 to 7% of the content of Ca. (6) It was ascertained that the lower limit of the determination of Ca could be extended down to about 0.001% by using Mg of higher purity as the base material.
A spectrographic method was studied to determine microamounts of Ca in Th metal and ThO2, and it was found that Ca in Th could be determined by exciting sample solution in a porous-cup electrode with the transient discharge source unit. The results obtained were as follows: (1) Th metal and ThO2 could be dissolved in HCl by adding a microamount of HF. Taking into account the spectral intensity of Ca, the concentration of Th solution was adjusted to 10 mg/mL. (2) The discharge conditions were E(discharge voltage)=225 V, C=22 μF, L=30 μH, R=2 Ω. (3) Preliminary discharge was done for 40 sec in order to photograph the spectra emitted in a stable discharge period. (4) The influence of HF which was added to dissolve the sample was examined, and this could be avoided by removing HF immediately after the dissolution of the sample. (5) Samples containing 0.024 to 0.3 per cent of Ca were analysed with Sr II 4215.52 Å/Ca II 3933.67 Å as the analytical line pair, the reproducibility being 7 to 9 per cent of the content of Ca. (6) It was ascertained that the lower limit of the determination of Ca could be depressed down to about 0.001 per cent by using Th of higher purity as the base material.
In view of comparative examinations and experiments were made on the physical and metallurgical properties, of the convex and concave sides of a high pressure steam turbine rotor shaft for 66,000 kW generator which had shown reversible deflection during its heat indication test. Given below are the findings of the said studies. (1) The thermal expansion coefficient of the convex side is about 0.1∼0.2×10−6 higher than that of the concave side. (2) With regard to the radial hardness distribution and the crystal structure of carbide, no significant difference is observed between the two sides. (3) The microstructures of the two sides show scarcely any clear difference, but the convex side had a smaller amount of ferrite-like transformation product and of the Mo contained in carbides than the concave side. Therefore, the amount of Mo contained in matrix is greater in the convex side than in the concave side. (4) The influence of solid-solved Mo in pure iron on the thermal expansion coefficient of Fe-Mo system was examined and made clear. From the above-mentioned findings, it may be concluded that the reversible deflection is primarily ascribable to the heat treatment performed in non-axial symmetry and the consequent eccentric distribution of Mo dissolved in matrix.
Reversible deflection was reproduced on model shafts by means of a model apparatus for heat indication test. As the third report concerning our general study on the reversible deflection noticeable in steam turbine shaft forgings, the results are published herein, showing that it is possible to produce reversible deflection intentionally. With the said model apparatus for heat indication test, it was made feasible to repeat easily a series of tests under all the same conditions, saving time and money. As a result of eccentricity of heat treatments such as at non-uniform austenizing temperature or for normalizing in non-axial symmetry, reversible deflection could be produced and that only on a model shaft of steel containing Mo as alloy metal among the several steels used in the present series of tests. It was also found that the reversible deflection is not produced by the segregation in non-axial symmetry.
A simple chelatometric titration method for the determination of Pb in leaded free cutting steel has been developed. Interfering elements are removed by MIBK extraction and Pb is then determined by titration with EDTA. The procedure is as follows: Weigh 5 g of sample, add HCl, HNO3 and HCl O4, and evaporate to fume. Cool, dissolve the residue with 6 N HCl in a 100 mL. Volumetric flask and make up to the mark with 6 N HCl. Pipet 20 mL of solution into a separatory funnel, add MIBK and shake for 30 sec. Drain off the aqueous layer. Add HNO3 and HCl O4 and evaporate to fume. Cool, add water and swirl to dissolve the salts. Add triethanolamine and excess EDTA. The solution is adjusted to pH 10∼11 with NH4OH. Add KCN and back-titrate excess EDTA with standard Ca solution using thymolphthalein complexone as indicator.
When titanium is heated by high frequency field in oxygen stream, titanium is burned explosively without use of flux, but the crucicle is eroded by the sudden rise of temperature, and the operation cannot be continned. In order to avoid such erosion, investigations were made on material and shape of the crucible, and condition of combustion. A crucible made of material containing Al2O3 and SiO2 in the ratio of 10:8 was used. Chips of the crucible were added to the center of the sample. After covoering up, the sample was preheated for 40∼60 seconds without oxygen flow just before the burning. The sample coule be burned completely without any erosion or damage to the crucible. The generated CO2 was frozen out with liquid oxygen and then was evaporated into a McLeod gauge, and the pressure was measured. The accuracy of the method was ±0.00021% and the reproducibility was ±0.00053% in standard deviation. Time reqired was about 16 minutes per sample.
The effect of Nb in the form of Fe-Nb alloy containing 70% of Nb added to sintered permanent-magnet alloy of the Alnico 5 type (8.3%Al, 15%Ni, 24%Co, 3%Cu, residue Fe) had been studied, particularly, in relation to their linear shrinkage, density magnetic properties, transverse rupture strength, pore size and microstructure. It had been found, hat the addition of Nb within the range of 0.35∼0.7% improves the qualities of Alnico 5 type alloys prepared by sintering in pure hydrogen, but large addition causes pore aggregation, rapid grain growth and detrimental effects on the rupture strength and the magnetic properties.
An electric contact material of silver-iron oxide was prepared from mixed silver-iron electrolytic powder and mixed Ag-Fe2O3-Fe3O4 precipitates by powder metallurgical process. The compact was sintered in the atmosphere of mixed CO-CO2 gas and the sintering behaviour of the silver-iron oxide compact was investigated by means of X-ray diffraction analysis and measurement of electrical properties of the sintered specimens. As the result, the optimum compacting pressure, gas composition, sintering temperature and sintering time for electrolytic powder system were determined respectively as follows: Below 1 t/cm2, \dfracCOCO+CO2 30∼35%, 850∼890°C, 3/4 to 1 hour re-pressin at 5 t/cm2 followed by 3 hour repressing, for precipitate powder system; about 4 t/cm2, \dfracCOCO+CO2 50∼60%, 850∼890°C, 3/4 t/hour re-pressing at 5 t/cm2 followed by 1\dfrac12 hour re-pressing, for precipitate system.
Co-precipitation of silver and iron salt was investigated in order to produce mixture of silver and iron oxide powders for electric contact material. A fine precipitate of salt mixture of 1∼10 μ was obtained by means of adding a mixed solution of silver and iron nitrate to a solutions of sodium carbonate (Na2CO3), ammonium carbonate ((NH4)2CO3), and amonium carbonate-ammonium benzoate mixture [(NH4)2CO3-(C6H5CO2)NH4]. The curves of the pH vs volume of added solution were determined for each system. The pH curve is a useful datum for establishing the conditions of preparation of the electric contact material.
The process of the early stage tensile deformation (≤σ=0.2%) of polycrystalline α-brass (70-30), was studied using Jacquets etch pit technique. Observations of etch pit arrangements in the same grain at various stages of deformation shows that the order of generation of glide dislocations agrees well with the results obtained from analysis without taking into consideration the influence of surrounding grains, but the effect of constraint from neighboring grains appeared in configurations of pile-up dislocation rows blocked by obstacles such as grain boundaries and sessile dislocations. As the deformation proceeds, the number of blocked dislocations increases and the mean free paths of newly formed dislocations are decreased.
The thermal conductivities of the mono-carbides having NaCl type structure in several transition metals of the fourth and fifth groups on the periodic chart were measured at 0°C and at the liquid-oxygen temperature. For these substances, larger conductivity by lattice than those by conduction electrons is concluded from the calculations of the Wiedemann-Franz ratio. The values of the measured thermal conductivity are compared and systematically discussed wich reference to the periodic chart.
The influence of bath composition and current density on the crystal structure, microscopic structure, W content, hardness and current efficiency of W-Co deposits obtained from tartrate bath was studied. The W content, the microscopic structure and the crystal structure of W-Co deposits were correlated with one another and could be classified into three groups with the increase of W/Co weight ratio in plating solution and of current density. The three groups were as follows: Group A) 20∼35 wt%W, angular microscopic structure, preferred orientation of hexagonal α Co solid solution exhibiting the (10\bar10) or the (10\bar11) plane being parallel to the surface; Group B) 36∼42 wt%W, intermediate microscopic structure, preferred orientation different from that in group A; Group C) 43∼52 wt%W, granular microscopic structure, diffused X ray diffraction pattern in the range of d=2.25 to 1.89 Å. The cause of this diffuseness of diffraction lines observed in high W deposits may be explained in terms of the increase of strain in α Co lattice owing to the supersaturation of W atoms in the lattice.
The hardness of W-Co electrodeposit obtained from tartrate bath is abnormally increased when it is heated at 700°C for 1 hour. The hardening process of W-Co deposits which were obtained under various plating condition was investigated, and the mechanism of this hardening was discussed after the examination of crystal structure by X ray diffraction method. The results obtained were as follows : It was found that the ordering transformation of αCo→Co3W took place in the deposit during the heating, though the ordering was not completed by heating at 700°C for 1 hour. The increase in hardness was almost proportional to the W content in the deposit, except in the case in which particular plating conditions such as low Co-content solution and high current density were adopted. The degree of hardening seemed to be dependent on the size, the amount and the distribution of ordering regions in αCo solid solution.