一批20号铸钢水轮发电机平衡大飞轮,因在外圆柱面中间部位普遍存在一圈白色偏析线而报废。金相分析表明,白色偏析线是含有大量氧化物的铁素体带;带中多处存在的结晶组织,经着色腐蚀证明是磷共晶和弥散磷化物。对偏析线取样化验,发现磷含量高达9％,旁证了白色偏析线是磷偏析的金相分析结论。 A group of No.20 steel hydropower turbine balance large flywheel, because of the outer cylindrical surface in the middle of a circle of white segregation line and scrapped. Metallographic analysis shows that the white segregation line is a ferrite band containing a large amount of oxides. The crystal structure exists in many places and is proved to be phosphorus eutectic and dispersive phosphide by color etching. On the segregation line sampling experiments, found that phosphorus content as high as 9%, concomitant white segregation line is phosphorus segregation of metallographic analysis.