高铬铸铁磨辊断裂分析

Study on High Chromium Cast Iron Fracture Grinding Roll

通过光学显微镜和扫描电子显微镜等手段,对断裂的高铬铸铁试样进行金相显微组织和断口形貌分析。结果表明,铸件中组织不均匀,存在空洞、疏松等内部缺陷。断口形貌呈现解理、准解理特征。裂纹主要是沿着碳化物与基体的界面扩展。在使用过程中奥氏体发生转变,体积膨胀,产生拉应力,结果使碳化物和基体的界面成为组织中强度较薄弱的区域。断裂区的碳化物比非断裂区的粗大且呈板条状,马氏体分布不均匀,存在较多的夹杂物,尖锐的端部容易造成应力集中,从而降低了材料的韧性。

The microstructure of metallographic specimen and fracture surface on high chromium cast iron fracture grinding roll were analyzed by optical microscopy and SEM.The results show that the microstructure of the roller were uneven,some inanition and loosen were found.Cleavage crack and quasi-cleavage were visible on the fracture surface.The cracks were mainly along the interface of carbide matrix and substrate.In the use of the process,martensitic transformation occurred,simultaneous volume expansion,resulting in tensile stress,So the interface of carbide and substrate become the weak region,so the majority of crack extended along the interface.Carbide in fracture zone were coarse and lath than the carbide in non-fracture.The distribution of martensite were uneven,and the inclusions were existence,sharp tip easily lead to stress concentration,thus reducing the material＇s toughness.