Influences of boron on the microstructural characteristics and wear performance of hypereutectic Fe-Cr-C-Mo-xB hardfacing alloy

In industrial production, addressing friction-induced wear is a significant research focus. Researchers aim to enhance wear resistance by adding low-cost Boron (B) to hypereutectic hardfacing alloys. This study investigates how varying B content (B-Free, 0.39 wt%, 1.03 wt%, 1.43 wt%) affects the microstructure and wear resistance of Fe-Cr-C-Mo-xB hardfacing alloys. Results reveal that increasing B content refines primary M7C3 carbide size from 36.9 μm to 15.5 μm and substantially increases alloy hardness from 690 HV to 1033 HV. EDS and TEM observations show B partially substitutes carbon (C) in M7C3 and Mo2C carbides, forming M7C3-xBx and Mo2(C1-xBx) carbides. Notably, at 0.39 wt% B, the alloy exhibits superior wear resistance with a smoother post-abrasion surface, absence of extended furrows, and minimal abrasive intrusion. Analyzing abrasive wear micro-mechanisms highlights the importance of the hard phase's shear resistance for wear resistance. Quantitative assessments through first-principle calculations reveal a continuous reduction in the mechanical modulus of the hard phase with increasing B doping, explaining reduced wear resistance at higher B levels. These findings hold promise for advancing hardfacing alloys in industry.