采用窄间隙埋弧焊工艺在相同焊接参数下对2.25Cr-1Mo-0.25V钢进行焊接, 选择冲击功相差较大的两个焊缝进行化学成分分析、力学性能测试、宏观断口及显微组织观察, 并分析了焊缝冲击功不稳定的原因。结果表明: 焊缝冲击功出现波动是由化学成分和组织不同造成的; 焊缝中的锰、硅元素含量较多时, 冲击功低, 韧性差; 组织粗大, 板条贝氏体较多时, 韧性和塑性低; 组织细小, 粒状贝氏体较多时, 韧性和塑性较高; 当冲击试样缺口开在板条贝氏体较多的区域时, M/A岛趋于直线排列, 容易形成裂纹, 冲击功较低。

2.25Cr-1Mo-0.25V steel weld seams were prepared by using narrow gap submerged arc welding under the same welding conditions, two weld seam samples with significant difference of impact energy were selected, their chemical composition and mechanical properties were analyzed, and their macrographs and microstructures were investigated. Meanwhile, the reason of the large difference of impact energy was analyzed. The results reveal that the difference of impact energy was caused by different chemical composition and microstructure. When the weld seam owned more contents of Mn, Si elements, it had poor toughness. Weld seam with coarse microstructure and lath bainite had weaker toughness and plasticity, weld seam with finer microstructure and granular bainite had good toughness. When the sample opened a notch in the area with more lath bainite, the permutation of M/A islands was tend to linear arrangement, cracks could be to form easily in the region, so impact energy was lower.