Microstructure and wear resistance of Fe-Cr13-C-Nb hardfacing alloy with Ti addition

Abstract

In order to achieve the maximum benefit from the carbide-forming elements Ti and Nb, it is very important to have a better understanding of the strengthening mechanism of the two carbide-forming elements in the hardfacing alloy.The Fe-Cr13-C-Nb hardfacing alloy with and without Ti addition were deposited respectively on carbon steel substrates by shielded metal arc welding. The carbide-forming elements in the two hardfacing alloys were S1-0.158Nb and S2-0.156Nb+0.263Ti(wt.%). Optical microscope (OM), scanning electron microscope (SEM) and energy-dispersive spectrometer(EDS) were used to investigate the effect of titanium addition on the microstructure of the hardfacing alloy. The impact experiment was conducted using the Charpy impact testing machine. The wear resistance was tested through a slurry rubber wheel abrasion test machine, and the wear behaviour was also studied.The results show that, the carbide precipitation of the Fe-Cr13-C-Nb hardfacing alloy was determined by Ti addition. Ti has greater affinity than Nb for carbon to form TiC, and the prior TiC precipitates act as nucleation sites for NbC to promote precipitation of complex carbides in the hardfacing alloy. The microstructure of the Fe-Cr13-C-Nb hardfacing alloy with titanium addition exhibited hard carbides dispersion in a tough martensite matrix, where the hard carbides provide the resistance to abrasion. So the Fe-Cr13-C-Nb hardfacing alloy with titanium addition showed a better wear resistance, and the wear mechanism was mainly interrupted plastic grooves with minimum depth and desquamation of carbides.