A709钢板在焊接生产过程中出现偏析带。由于普通探伤手段无法对钢板的偏析程度进行检验，试验采用对比方法，综合力学、化学、金相、扫描电镜等检测手段对其进行检测。结果表明：A709钢板本身就存在偏析带，说明此偏析带是轧制过程出现的，并非是因为生产过程的焊接作用。同时观察到此偏析带含有大量硫化物，甚至造成微裂纹出现，严重地影响了钢板的焊接力学性能，造成了巨大危害。

The segregation phenomenon appeared in the process of A709 steel plate welding production. Common detection methods can’t test the degree of segregation of the steel plate, so the causes of linear segregation of welding test plate were investigated with comparing method by means of mechanics examination, chemical compositions analysis, metallography examination, scanning electron microscopy and so on.The results show that there was segregation band in A709 plate, it illustrats that the segregation band was came from the process of rolling not the process of welding. At the same time, a lot of sulfur and micro cracks was observed in the segregation band, it influenced seriously mechanical properties of welding steel plates and caused great harm.