The microstructure of weld metal for SAW is acicular ferrite, and there is new type bainitic microstructure in heat-affected zone, grains are well-distributed and good joining in bond area.

• 埋弧焊焊后不热处理焊缝部分组织为针状铁素体，熔合线结合良好，组织分布均匀，晶粒细小，热影响区组织为新型贝氏体。