Microstructure and wear resistance of in situ TiC-reinforced low-chromium iron-based hardfacing alloys

Strengthening low-chromium iron-based alloys with multiple alloy elements is a crucial strategy for developing "casing-friendly" hardbanding materials. In this paper, four kinds of low-chromium iron-based hardfacing alloys with different Ti contents were prepared by flux-cored arc welding technology, and the effect of Ti content on the microstructure, hardness, and wear performance under the abrasive wear and dry sliding wear was analyzed. The in situ TiC-reinforced iron-based hardfacing alloys exhibited microstructure comprising austenite, martensite, carbides, and in situ TiC particles. The in situ formation of TiC particles consumed the carbon in the alloy and thus raised the martensite start temperature, resulting in a reduction in the mass fraction of austenite and an increase in the martensite. Among the four hardfacing alloys, the alloy with 5 wt.% Ti exhibited the highest hardness (836.3 HV0.2) and the best wear resistance due to its highest martensite mass fraction (69.97 wt.%). The matrix with in situ TiC particles and martensite effectively resisted the cutting of abrasive grains and the wear mechanism developed from the microplowing in 0Ti alloy to microcutting in in situ TiC-reinforced iron-based hardfacing alloys in abrasive wear tests. In dry sliding wear tests, TiC particles were released and slid on the surface of the alloys, resulting in the formation of grooves, while the formation of the tribochemical reaction layers contributed to a reduction in the friction coefficient and wear rate. This study provides a theoretical foundation for the development of "casing-friendly" hardbanding materials.