研究了X100和X80焊管焊缝的显微组织和冲击韧性，详细分析了焊缝韧性降低的原因。通过组织分析，得出显微组织不均匀即M/A组元和夹杂物聚集是降低焊缝韧性的重要因素。通过氧、氮、氢含量的测定和夹杂物分析，可知焊缝含氧量高导致焊缝中含有较多大尺寸非金属夹杂物，从而显著降低焊缝韧性。脆性M/A组元是导致焊缝韧性降低的另一个重要因素。控制焊缝韧性降低的主要措施为控制焊缝含氧量和脆性M/A组元含量。%In this paper, the weld microstructure and impact toughness of X100 and X80 welded pipe were studied, and the cause of weld toughness decrease was detailedly analyzed. Through structure analysis, it got that nonuniform microstructure, that is to say M/A constituents and inclusions aggregation are the key factors to lower weld toughness. Through the determination of the content of oxygen, nitrogen, hydrogen, and inclusion analysis, it showed high oxygen content lead to more big size of non-metallic inclusions in weld, thus significantly reduce the weld toughness. The brittle M/A constituents are the other important factor. Control the oxygen contents of weld and the content of brittle M/A constituents are the main measures for controlling weld toughness reduce.
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