Effect of Mo content on microstructure and wear resistance of hardfacing layer of high chromium cast iron
The high chromium cast iron surfacing layer is widely used in the internal lining of various large industrial equipment due to its high wear resistance.It is found that the carbide formed by the Mo element can provide core points for the primary carbides to refine the structure.However,whether the Mo element plays other roles besides providing core points remains to be studied.To investigate the influence of Mo content on the organization and per-formance of the high chromium cast iron surfacing layer,Mo ultra-carbon high chromium surfacing wear-resistant plate was designed.The effect of the Mo element on the structure and phase composition of the surfacing layer,as well as the surface and longitudinal section of the wear surfacing layer,is analyzed using XRD.The distribution in each phase,and further using the hardness and dry sand abrasive wear test,the influence of Mo alloying on the hard-ness and wear resistance of high chromium and high carbon surfacing layer was studied.The results indicate that the structure of the Fe-Cr-Mo-C alloy surfacing layer mainly consists of the gamma phase and M7C3(M=Fe,Cr).With the increase of Mo content,the primary carbide content in the surfacing layer decreases,the austenite content increases,and the size of a single primary carbide decreases first and then increases.The hardness of the primary car-bide increases,and the macroscopic hardness of the surfacing layer increases and then decreases;after wear,the trun-cated pattern of the primary carbide decreases,and the sample showed the peeling of eutectic carbide.After adding 0.13%Mo,the grinding loss weight was reduced by 13.6%,and after adding 0.30%Mo,the grinding loss weight increased by 20.0%.This is because the inclusion of Mo atoms increases the hardness of the primary carbide,but with the content of primary carbides decreasing,it results in an initial increase and then a decrease in the hardness of the surfacing layer and a corresponding variation in grinding loss weight.The research results provide guidance for selecting the appropriate Mo addition in the preparation of high chromium cast iron surfacing layers.The composi-tion of this test is designed with three samples with a Mo content ranging from 0.04%to 0.30%.The results indi-cate that the primary carbide shows a trend of first refinement and then coarseness,which necessitates further study.
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