The Effect of Microstructure on Properties of Fe-Cr-C-Nb/Ti Hardfacing Alloy

Hardfacing is one of the most useful and economical ways to improve the performance of components submitted to severe wear conditions. In this paper, a new kind of alloy called Fe-Cr-C-Nb/Ti alloy system for wear resistant successfully with the shielded metal arc welding (SMAW) method has been studied. The microstructure and wear resistant of hardfacing alloys reinforced with primary carbides were compared in this study. Meanwhile, the average hardness, the abrasion weight loss and microstructure of deposited metal were systematically studied by optical microscopy, scanning electronic microscopy and energy dispersive spectrum analysis. The results showed that the microstructure of the best optimizing hardfacing layer was the mixed martensite and little retained austenite, and NbC/TiC particles distributing dispersively in the matrix. The amount of low-carbon martensite and high-carbon martensite was identical. The alloy system showed high wear resistance due to the formation of dispersed MC type carbides and good toughness due to the exist of low carbon martensite in the matrix. The hardfacing alloy reinforced with complex carbides was also investigated, the microstructure was analyzed and its hardness and wear resistance were evaluated. In conclusion, the distribution, the chemical composition and the amount of the carbides, as well as the matrix microstructure are all factors to influence the crack resistance, hardness and wear resistance of the hardfacing alloys.