桥梁用宽厚板冲击性能异常原因分析

Analysis of reasons for the abnormal impact properties of heavy plates for bridge

对桥梁用宽厚板进行力学性能检验时,发现钢板的冲击性能异常,采用金相显微镜、扫描电镜和电子探针对钢板进行观察和分析。结果表明,钢板的头部和中部的组织有明显的差异,同时钢板中存在严重的C、Mn等元素偏析。分析认为,钢坯不同部位的冷速不均导致钢板的头部和中部组织存在明显差异,而元素偏析导致偏析条带上聚集了大量的M/A,在横向冲击时带状的M/A作为断裂源很容易连成一片,导致试样的横向冲击功较小。

The abnormal impact properties of heavy plates for bridge were found in the mechanics performance testing. The plate samples were observed and analyzed by means of metallurgical microscope, scanning electron microscopy and electron microprobe. The results showed that there were some obvious different structures between the head and the centre of the plates, and the C, Mn and some other elements segregation bands were observed. It was concluded that the differences of structures between the head and the centre were caused by the different cooling speed of different parts, and the element segregation led to forming the M/A segregation bands, which would tend to link together as the crack sources in the transverse impact, and lead to the abnormal impact properties.