Root Cracking in One Side Full Penetration Welding (Second Report)

In the first report, we described that root cracking in one side full penetration welds may be divided into two kinds, notably, cracking in weld metal and cracking in heat-affected zone, and that in order to minimize these cracks, low hydrogen type electrodes under fillet type welding process would be preferable following preheating at the temperature of 75°C.Following our first report, we continued our experiment on root cracking in one side full penetration welds in anticipation that the cracking in heat-affected zone could be prevented by surfacing groove faces.The summaries of our investigation are as follows : (1) Surfacing would be exceedingly effective in preventing root cracking in heat-affected zone. This phenomenon was also authorized in Fisco restraint test. (cf. Fig. 1, Fig. 4) (2) Surfacing has no effect on cracking in weld metal.(3) Cracking in weld metal is considered to be attributable to the stress concentration due to shrinkage and micro cracks originating in weld metal. It is desirable to further investigate about this problem.