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

Abstract

AbstractThe hypereutectic Fe-Cr-C hardfacing alloys with different contents of TiB2 and Nb were prepared by self-shielded 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.