The results showed that nonmetallic inclusions in weld seam served as crack initiation site under external bend load, and large amount of m a structure resulted in cleavage fracture of weld seam.

结果表明，焊缝金属中存在的非金属夹杂物，在低应力作用下形成微裂纹成为裂源，加之焊缝组织中存在大量的M A结构群，从而发生焊缝金属在室温下的解理断裂。

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