球墨铸铁的等离子束表面强化研究

Surface Strengthening Treatment of Nodular Cast Iron by Plasma Beam

利用等离子束对球墨铸铁进行表面熔凝和表面合金化强化处理。采用扫描电镜、X射线衍射仪、硬度计、电化学工作站和磨损试验机等设备对强化层的组织、性能进行测试。结果表明:等离子束表面强化处理后,球墨铸铁表面石墨相完全消失,形成的改性层显微组织主要是枝晶结构;改性层的硬度最高值出现在次表层,熔凝层的最高硬度为1243HV0.1,合金化层的最高硬度达1343HV0.1;熔凝层和合金化层的耐蚀性和耐磨性相对于基体来说有很大的提高,并且由于合金化层具有更多的碳化物,组织更加致密均匀,其耐蚀性和耐磨性明显好于熔凝层。

The surface of nodular cast iron was strengthened by means of surface melting and alloying with plasma beam.The microstructures and the phase structures were analysed with SEM and XRD.The corrosion resistance and wear properties as well as microhardness were tested by hardness tester and wear tester.The results show that the near surface graphite of the nodule disappears completely and there are mainly dendrites and eutectics in the modified layers after surface treatment of nodular cast iron by plasma beam.The highest microhardness in the melted layer and alloyed layer,appearing in the subsurface,are 1243HV0.1 and 1343HV0.1,respectively.The corrosion resistance and wear re sistance of the melted layer and alloyed layer are enhanced remarkably comparing with the matrix.Furthermore,the corrosion resistance and wear resistance of the alloyed layer are better than that of the melted layer due to more hard phases,finer and more homogeneous structures in the alloyed layer.