Four weld metals respectively named LOLT (Low oxygen low titanium), LOHT (Low oxygen high titanium), HOLT (High oxygen low titanium), HOHT (High oxygen high titanium) with varying Ti and O additions were prepared by laboratory high heat input welding test. The effects of Ti, B and O on microstructure and impact toughness of these weld metals were investigated. The results show that with 205 kJ/cm high heat input, the contents of O and Ti in LOLT were appropriate, and a large number of cross-distributed acicular ferrite were formed, which improved the impact toughness; with the increasing Ti addition, granular bainite was formed in LOHT, which deteriorated its impact toughness. Compared with LOLT, the number of inclusions in HOLT was increased due to the higher O addition. Meanwhile, coarse grain boundary ferrite (GBF) was formed at prior austenite grain boundary because the interaction of B to the excess O prevented its segregation at austenite grain boundary, which resulted in the decrease of weld metal impact toughness. However, as Ti addition increased again, the number of inclusions in HOHT did not change much but GBF was not formed, which improved the impact toughness.

采用实验室高热输入焊接方法制备了四种焊缝金属，分别命名为 LOLT（低氧低钛）、LOHT（低氧高钛）、HOLT（高氧低钛）、HOHT（高氧高钛），添加不同的 Ti 和 O测试。研究了 Ti、B 和 O 对这些焊缝金属的显微组织和冲击韧性的影响。结果表明，在205 kJ/cm的高热输入下，LOLT中O、Ti含量适宜，形成大量交叉分布的针状铁素体，提高了冲击韧性；随着Ti添加量的增加，LOHT中形成粒状贝氏体，降低了其冲击韧性。与 LOLT 相比，HOLT 中的夹杂物数量由于 O 添加量增加而增加。同时，粗晶界铁素体 (GBF) 在原奥氏体晶界处形成，因为 B 与过量 O 的相互作用阻止了其在奥氏体晶界的偏析，导致焊缝金属冲击韧性降低。然而，随着Ti添加量的再次增加，HOHT中夹杂物的数量变化不大，但没有形成GBF，从而提高了冲击韧性。