Q345B中厚板心部裂纹剖析

Analysis on central cracks in medium and heavy plate of Q345B steel

采用扫描电镜观察,发现中厚板心部裂纹与2种异常组织共存。采用显微维氏硬度计测量,2种异常组织的HV0.05硬度值分别为566.2、391.6,对应于马氏体和贝氏体组织。X射线能谱仪成分分析,发现异常组织中存在锰和铬元素的富集,说明成分偏析导致心部出现异常组织,异常组织造成局部应力,引起开裂。

Observating the microstructure of Q345B plate by SEM,the coexistence of central cracks and two kinds of abnormal microstructure was found in the plate.Measuring its hardness by microhardness tester,HV0.05 value of the two kinds of abnormal mictrostructure was 566.2 and 391,which is corresponding to martensite and bainite zones,respectively.Analyzing its composition by X-Ray Energy Spectrometer,the concentration of manganese and chromium was found in the abnormal microstructure.The segregation of composition caused to form the abnormal microstructure,which can result in partial stress to form cracks.