高铬铸铁轧辊断裂原因分析

Fracture Analysis of High Cr Casting Iron Roller

针对某公司高铬铸铁轧辊断裂事故,通过外观检测、硬度测量、SEM断口扫描、能谱分析和金相组织观察,研究了轧辊断裂的原因。断口宏观观察到裂纹源区、裂纹扩展区和瞬断区;SEM断口扫描发现轧辊断裂为典型疲劳断裂,断裂方式为穿晶断裂;能谱分析显示大量析出的碳化物为M7C3、M23C6、Mo2C等,组织中类球状黑色物质是由石墨和少量的氧化物夹杂组成;金相组织中共晶碳化物沿晶界呈网状分布,这有可能是造成轧辊疲劳断裂的原因。

Aimed at crack accident of high Cr cast iron roller from a company, through analyzing the ap- pearance, the fracture microstructure with the help of SEM （scanning electron microscope）, the hard- ness measurememt, the energy spectrum and the microstructure, origination of the crack in high Cr cast iron was approached. Macro-fracture is characterized by crack source area, propagation area and instan- taneous fault area. SEM analysis shows that the crack of the roller is characterized by fatigue fracture with transgranular crack. The energy spectrum reveal that the carbide is composed of M7C3. Me3 C6 、 Mo2C and so on,and spherical black phase consists of graphite and some oxide inclusion. The eutectic carbide with net-like shape is distributed along the grain boundary, which might be responsible for the crack.