Effect of Vanadium Content on Microstructure and Wear Resistance of Fe-Cr-V-B-C System Hardfacing Alloys

Fe-Cr-V-B-C system high boron hardfacing alloys were prepared on Q235A steel surface by self-shielded open arc welding with composite powder particles and H08A solid wire. The effects of vanadium mass fraction (0-7.5%) on the microstructure and wear resistance were studied. The results show that when the mass fraction of vanadium was 0, the hardfacing alloy consisted of α-Fe, M₂B and M₃C phases. When the vanadium mass fraction was 1.5%, the content and size of the bulk M₂B phase increased, and point and cross flower-like VC phase was precipitated between grains. When the vanadium mass fraction increased to 3.0% and 4.5%, the primary M₂B grains were refined. When the vanadium mass fraction increased to 6.0%, needle and strip V₃B₂ phase was precipitated between and within M₂B phases. When the vanadium mass fraction increased to 7.5%, the V₃B₂ phase content increased significantly and the M₂B phase content decreased. With the increase of vanadium content, the hardness of the hardfacing alloy first increased and then decreased, and the wear mass loss first decreased and then increased. When the vanadium mass fraction was 3.0%, the hardfacing alloy had the highest hardness of 61.6 HRC and the smallest wear mass loss of 0.019 4 g, indicating the hardfacing alloy had the best wear resistance.