NDT温度に及ぼすクラックスタータービード溶接の影響に関する研究

抄録

In ASME Code Sec. III, the value of the reference nil-ductility temperature RT_EDT has an important significance to determine the result of the fracture mechanics evaluation. While in the standard both the drop-weight test and Charpy impact test are required to determine the RT_NDT, in practice it is normally determined only by the nil-ductility transition temperature (T_EDT) obtained by the drop-weight test.
The causes of data scatter in T_NDT were investigated to establish appropriate conditions of crack-starter bead welding. Drop-weight tests were carried' out for nuclear vessel steels by changing welding conditions to examine the effects of welding amperage and shapes of welding table on T_NDT. The results show that the preparation of crack-starter bead by small welding amperage should not be allowed, because it makes the measured T_NDT non-conservative, and that it is important to use a welding table which increases the cooling rate of specimen.
Furthermore, the authors proposed methods for estimating T_NDT of nuclear vessel steels by using Charpy transition temperatures.