Abstract
Welded tear test piece of Kahn type was proposed to investigate the effect of manual arc welding on the notch sensitivity of structural mild steel plates, 11 charges of rimmed and killed ones produced by four representative steel plants in Japan. Snigle bead was deposited on one side of plate surfaces, and then, machined flush to the surface. The saw cut was located alongside the deposited bead to evaluate the notch sensitivity of heat-affected zones of the base material.
For comparison, tests were also carried out with standard Kahn tear test pieces of un-welded plates.
Table 5 and Fig. 14 show the transition temperature of steel plates thus determined before and after manual arc welding. Fig. 14 also demonstrates the relations between Mn/C ratio and transition temperatures, oblique zones in the figure showing the ones of American semi-killed and killed steels on Kahn's data. Welded plates generally showed higher transition temperatures than unwelded plates, ranging from 5 to 11°C in 13 mm thick and 4 to 13°C in 23 mm thick ones of rimmed steels, from 1 to 13°C in killed steels, 23mm thick. But these adverse effects. were comparatively slight, so it could be concluded that the notch sensitivity of mild steel plates was but slightly increased as the result of manual arc welding so far as fracture transition was concerned. Moreover, the amount of rise in transition temperature after welding was not related at all to the notch sensitivity of unwelded plate studied in this report.
