| 摘要 |
PURPOSE:To prevent the embrittling after stress relief annealing and improve toughness by limiting the composition ratios of the specific compositions in submerged arc weld metal. CONSTITUTION:The composition of submerged arc weld metal is set at 0.02- 0.090% C by weight %, 0.1-0.6% Si, 1.0-1.9% Mn, <=0.2% Ni, 0.1-0.7% Mo, 0.01-0.03% T, 200-400ppm O, <=100ppm N and the balance F with impurities. At this time, the composition ratios of the Ni, Ti, O, N in the composition are limited. The reasons for this lie in that with the Ni the inclusion of the Ni in steel plates owing to dilution occurs in some times but if it exceeds 0.2% by wt%, an optimum amount of Ti for toughness shifts to the slight region side and SR embrittling is not improved. If the Ti is below 0.01%, toughness is not improved and in excess of 0.03%, SR embrittling is conspicuous. If the O is out of the limited range, toughness lowers. With the N in excess of the limited range, toughness lowers. |
