Microstructure and Properties of Fe-Cr-C Hardfacing Alloys Reinforced with TiC-NbC

The hypereutectic Fe-Cr-C hardfacing alloys with different contents of TiB2 and Nb were prepared by selfshielded flux cored arc welding.The microstructure of a series of hypereutectic Fe-Cr-C hardfacing alloys added with various TiB2 and Nb contents was investigated by using optical microscopy(OM),scanning electron microscopy(SEM)and X-ray diffraction(XRD).In addition,their Rockwell hardness,microhardness and resistance to abrasive wear were tested.The results showed that the microstructure of a series of hypereutectic Fe-Cr-C hardfacing alloys consisted mainly of martensite,austenite,primary M7C3 carbides and eutectic M7C3 carbides.With the addition of TiB2,a new hard-phase TiC was produced in the hardfacing alloys.And in the alloys added with TiB2 and Nb,a new hard composite phase TiC-NbC was formed.The microhardness of the matrix was improved by adding TiB2 and Nb,but the effect on the Rockwell hardness of Fe-Cr-C hardfacing alloys was insignificant.The addition of TiB2 and Nb can also decrease the size of the primary M7C3 carbides and make the primary M7C3 homogeneous.As a result,the reinforced matrix,the more homogeneous primary M7C3 carbides,and the new hard-phase TiC-NbC all improved the wear resistance of Fe-Cr-C hardfacing alloys.