In this Report the authors intend to announce the results of welding research using radioactive isotope S
35. In this experiment S
35 was used as a tracer to examine the state of equilibrium between slag and weld metal with respect to S in the case of electric arc welding. S
35 (in the form of sodium sulphate, Na
2SO
4) in the coating of electrodes passes to slag and weld metal through welding, so that by measuring the intensity of radioactivity of both slag and weld metal, the distribution ratio can be known and by comparing with that of coating the passing ratio can be determined.
As the result of thin experiment it was known that :
1) In spite of its weak energy, a small amount of S
35 can be detected from outside, when it exists in the weld metal, so that the segregation of S in weld metal can easily be determined by Geiger-Müller counter.
2) The passing ratio increases gradually for both slag and weld metal in the case of abrupt cooling (S in flux ranging 0-0.09 wt.%), but it begins to decrease over the range of 0.06% of S in the case of slow cooling.
3) Vaporization increases with increase of S% in the coating. The slower cooling speed, the more vaporization in the case of same amounts of S contents in the coatings.
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