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采用ＮＲ４００自保护药芯焊丝焊接厚板高强钢，对多层焊缝的组织、夹杂物及焊缝的韧性进行了研究．结果表明，焊缝柱状区和粗晶加热区组织主要由先共析铁素体和铁素体加第二相所组成，焊缝中较高的含铝量加速了奥氏体的高温分解．焊缝夹杂物多为球状复合氧化物，平均尺寸为０４６μｍ．夹杂物往往成为焊缝断裂的起源，对焊缝冲击韧性有不利影响．自保护药芯焊缝具有优良的冲击韧性，４０Ｊ冲击功所对应的转变温度低于－５０℃，满足工程结构对韧性的要求．焊接位置对焊缝断裂性能有影响，横焊优于立焊．
The NR400 self-shielded flux cored wire was used to weld high-strength steel plate, the microstructure, inclusions and weld toughness of multi-layer weld were studied. The results show that the microstructure of the weld bead and the coarse grain heating zone mainly consists of proeutectoid ferrite and ferrite plus the second phase. The higher aluminum content in the weld accelerates the pyrolysis of austenite. Weld inclusions mostly spherical composite oxide, the average size of 0 46μm. Inclusions often become the origin of weld fracture, adverse impact on the toughness of the weld impact. Self-shielded flux cored weld has excellent impact toughness, the corresponding transformation temperature of 40J impact energy is lower than -50 ℃, which meets the toughness requirements of engineering structure. Welding position of the weld fracture performance, horizontal welding is better than vertical welding.