After completing the first report, the authors made comparative study of radiographic examinations by X-Ray and GAMMA-Ray in respect of range utilization, advantage and disadvantage and nrotection from radiation, and the results obtained are as follows: 1. Inspection by the 1, 000 KV X-Ray can be applied only to objects which can be carried into the specified inspection-room. Such inspection is available not only for steel plates of thickness 5"-6" but for various castings which differ in thickness. It must be noted, howevrer, that the films for such inspection must be imported ones for the time being. 2. The portable 150 KV X-Ray, which is available for inspection of steel plate up to 1.6 inches in thickness, can be used for examination of welded parts at any site of work desired. 3. It is recommended that where the 1000 KV X-Ray and 150 KV X-Ray (portable).can ribt be annlied. GAMMA-Ray of Isotope (Co60) is to be used, for instance, pipe welding parts and the like. It shuld be a concern of great import that as it is very difficult to provide proper protection against the radiation of the GAMMA-Ray, special care must be taken in order to minimize the undesirable effect by keeping at a proper distance from the source of radiation or making the time of exposure to radiation as short as possible.
The author wrote in the 1st report on the welded strength of joint made by the gas pressure welding method under the most favourable conditions and in the present paper discusses applicability of this process in the field. It is learned as a result that, if only the upset surfaces are perfectly cleaned of rust, the welded strength will be sufficient. For testing the welded part, from the standpoint of principle, magnaflux method was found the most reliable among the metallurgical, supersonic and magnaflux tests. As the first experiment of welding different metals, the writer joined steels with different carbon contents and gained almost ideal results, so he proceeded to apply his method to the welding of mild steel with satisfactory results. Open butt welding, one of the gas pressure welding methods, was also studied and it was found that unless the joining parts were massive enough, this was inferior in may respects to closed butt welding. Further he carried out the welding of piges and found that when the ring burner was usedand the joining surface properly beveled before welding, all the ruptures of welded pipes occuredubytension test in the moter part, not on the weld;and as the appearance of the inner part of the welded pipe was very good, it would never offer any resistance to the flowing fluid. Moreover, from the principle used, high degree of air and water-tightness might well be expected and this was also ascertained by experiment. And this process, in actual operation, does not necessitate any packing of welding pipes witn reducing gas, e. g., H2, for an oxy-acetylene flame is itself reducing. Through the foregoing discussions, it was confirmed that closed butt gas pressure welding was one of the most reliable methods for the welding of rods and pipes.
This report shows the difference in moisture absorption between some coated electrodes stored in packages and others left in the atomosphere. In the experiments, the coated electrodes stored in packages absorbed moisture gradually over a long time, and the degrees of moisture absorption for three months were about four. percent. For reference, the author carried out the tension test and found that the effect of four percent moisture absorption of coated electrodes on mechanical properties of weld was not so remarkable.
Welding residual stresses at various points in the groove-slit type specimens as shown in Fig. 1 were welding by X-ray diffraction method in connection with welding variables. And the changes in stress due to removal of external constraint and local post-heating were also determined.