Abstract
In previous studies, the total flashing phenomena of the specimen to be welded have been discussed from the waveforms of flashing voltage and flashing current of the steel sheets.
The purpose of this study is to examine the flashing phenomena of limited part of the specimen to be welded. The materials used are of carbon steels, copper and aluminum sheets. The local flashing phenomena of the specimen to be welded are detected by the intensity of the light from the part through the slit of 1.2 mm width placed in 7 mm from the welds. The following results are obtained.
1. The local flashing is a discontinuous phenomenon, namely the flashing of several times occur at intervals of 1 or 2 ms after the flashing off of 10 up to 40 ms or 40 ms and over.
2. Such a periodical flashing is extensively in evidence during the flashing of low or medium carbon steel, copper and aluminum.
3. There is a secondary no load voltage that makes the maximum number of local flash times. The voltage is of about 6 volt in this experiment of low carbon steel sheet.
4. The mechanical properties of the welded joint of low carbon steel sheet can not attain to the excellent results under the conditions of the secondary no load voltage that makes the maximum number of local flash times.
5. There is risk of upsetting the several parts of the specimen after the flashing off of more than 10 ms, even if the carbon steel sheets are welded under the optimum welding conditions.
