With a view to consider the approximate range of desirable contents of manganese and silicon in the welding core rods for steels, the following investigations were performed. 1) Low carbon steel rods having low contents of manganese and silicon have been used generally up to this time as welding core rods, but there is no reliable basis for the general practice according to which manganese and silicon contents of the welding core rcd should .be very low. 2) Referring to the opinions of Korber and Oelsen and cf H. Schenck, I set the theory of deoxidation with manganese and silicon in order and described the conditions of obtaining clean steels. 3) I derived the equations for explaining the interrelations anmong the [O], [Mn] and [Si] concentrations of molten irons in equibrium states and drew iso-oxygen-concentration lines versus [Mn] and [Si] concentrations. 4) Using the diagram showing conditions of obtaining clean steels and the iso-oxygen-concentration lines, I discussed the desirable range of manganese and silicon contents before the solidification of molten irons deposited by welding to obtain excellent welds, and supposed an approximate range of manganese and silicon contents of welding core rods necessary for depositing such desirable molten irons.
The Purpose of this investigation was to compare working efficiency of divergent nozzle and straight nozzle. From the nature of divergent nozzle which is primarly designed by the amount of oxygen flow and the throat area, oxygen pressure of a given divergent nozzle has to be always kept at constant pressure. Therefore, experiments were carried out with each 2 sets of divergent and straight nozzles having design variables as shown below: 1) Oxygen pressure : 3.5 kg/mm. Amount of oxygen flow : 2766 1/hr 2) Oxygen pressure : 4.0 kg/mm. Amount of oxygen flow : 3806 1/hr. Keeping other factors at constant, structural steel of 12, 20, 25 and 50 mm thickness were gas tutted with various cutting speed by both type of nozzles. Equal results were obtained by either type, that is, cutting speed at zero drag and maxirrium cutting. speed obtainable were found to be exactly equal. Since the amount of oxygen flow is diffrent; above result shows that the cutting efficiency of divergent nozzle is superior tp that of straight nozzle. 27.4% of oxygen consumption can he saved by using divergent nozzle. Ideal shape of divergent nozzle for different thickness of steel plate, that is, proper operating pressure and throat area are to be obtained through repeated and systematic investigaticn of this kind.
Okada's screw-conveyer type coating machine has strong points in continuous operation, less material and floor space are needed, and having comparatively high working efficiency. The experimentally manufactured machine No.1 showed some defects in design, and some difficulties on fabrication. The authors have successfully manufactured machine No.2 after four years of devotion to improve the weak points found in the machine No. 1. This paper is divided into the following four sections aiming to explain principles applied to remodel the original one comparing the machine No.1 and No. 2. A) Equipment to feed core wire. B) Equipment to supply flux by pressure. C) Equipment to hold and drop coated rod. D) Equipment to convey and dry coated rod. Results of the investigation are discussed. Weak points are pointed out and suggestions for further improvement are given in the conclusion.
As the fundamental investigation for weld stresses, the authcr studied the prcblem of rectangular plate wtih one-dimensional stress. At first we did the following experiments : 300×110×2.3mm rectangular plates were heated along their center lines by particular heating equipment especially prepared. At high temperature the part near the heated zone behaves plastic deformation, and when the plate cools down to room temperature, residual stresses grow in consequence of these plastic strains. The residual stresses were measured by means of Heyn's method and dividing one. These experimental values of residual stresses are shown in Fig. 13. While the author has developed plastic theories of thermal and residual stresses of rectangular plate with one-dimensional stress distribution, and our theoretical values of residual stresses agreed with the experimental ones. We will study the problem of circular plate with two-dimensional stress distribrition in future.
0.6 per cent Carbon steels were brazed with pure copper, copper contained 4 percent Nickel, and with α-brass. Brazing in the electric furnace, passing through hydrogen, was compared with the oxyacetylene brazing method. Good results were obtained in the former. As the joint distance decreases the tensile strength of the brazed joint increases. In this case, it is largely due to the notch effect of tensile specimen rather than the effect of alloying layer.
In order to consider the mechanism of welding cracks and the relation between the types of welding cracks and the residual stresses, the stresses induced by welding on the surfaces of rectangular and groove-slit type specimens of mild steel as shown in Fig. 1 and Fig 2 were determined by the X-ray diffraction method. Stresses were calculated from the shift of the cobalt K α1 ring diffracted by the surface of the specimen. The measurements were carried out at twelve points on the rectangular specimen and at seven points on the groove-slit type specimen. Silver powder was adopted as the standardizing medium The result values are shown in Table 6 for the former and in Table 7 for the latter The distributions of stresses are to be easily seen in Fig. 6 and in Fig 7. The author considered the relation between these observations and the results of his previous research on welding cracks.
By the experiments on the butt joint with splice plates, connected by the rivet and fillet weld combined, the anther measured the deformation arising from repeated tensile static load, and determined the residual and elastic strains of joint. From these results, the auther calculated the apparent mcdulus of elasticity of the composite joint, and the "coefficient of cooperation" in rivet & weld respectively, at proof and ultimate loads. Besides, the effect of order of execution of riveting & welding upon those results was investigated by the auther.