Effect Of N,Nb,W On Microstructure And Properties Of Fe-Cr-N-Nb-W Surfacing Layer

As a commonly used surface repair method,surfacing technology can regenerate wear parts,extend the service life of the equipments,and have extensive implications for resource conservation.In this thesis,based on the traditional Fe-Cr-C surfacing alloy,three kinds of surfacing alloys,Fe-Cr-N-Nb,Fe-Cr-N-W and Fe-Cr-N-Nb-W,were designed.The self-protecting open arc welding method was used to prepare the surfacing layer,and the effect of N,Nb and W elements on the microstructure and properties of the surfacing layers were researched.The results of experiment are as follows,?1?In the Fe-Cr-N-Nb surfacing alloy,Nb carbonitride hard phases formed in the surfacing layer and dispersed in the matrix.The wear resistance experiment result shows that the addition of appropriate amount of Nb and N elements in the surfacing layer can improve the wear resistance of the Fe-Cr-N-Nb alloy,and the wear resistance and the number of hard phases of the Fe-Cr-N-Nb alloy can be improved.When the mass fraction of N element in the flux-cored wire is 3 wt.%and Nb element is 10 wt.%,the surfacing layer possesses the higher hardness and the better wear resistance,the hardness is HRC58.4 and the mass loss is0.173g.?2?In the Fe-Cr-N-W surfacing alloy,an eutectic compound such as Fe₃W₃C,Fe₆W₆C,M₇C₃ and a small amount of primary hard phase W₂N were formed.When the mass fraction of W element in the flux-cored wire is 16 wt.%,the hardness of the surfacing layer is HRC51.2 and the mass loss is 0.208g.The wear resistance of the surfacing layer is optimal.?3?In the Fe-Cr-N-Nb-W surfacing alloy,as the W content in the surfacing alloy increased,W reacted with Fe and C to form phases WC,Fe₇W₆ and Fe₃W₃C,Nb reacted with C and N to form carbonitrides such as Nb₂C,NbC,and NbN.The wear resistance test shows that the eutectic compounds of niobium carbonitrides and tungsten and the fine precipitates in the matrix makes the abrasive particles embed in the surface of the Surfacing layer with large resistance,and the good matching of the matrix with the hard phase effectively hinders the abrasion of the wear particles to the micro-cutting of the surfacing layer.In summary,N,Nb and W alloy elements can generate different carbonitrides and eutectic compounds in the Fe-Cr-N-Nb-W surfacing alloy,respectively.They can distribut in the matrix structure and coordinate with the matrix structure.Significantly improve the hardness and wear resistance of the surfacing alloys.