Effect of molybdenum on the microstructure and wear resistance of hypoeutectic Fe-Cr-B-C hardfacing alloys

Hypoeutectic Fe-Cr-B-C hardfacing alloys with different molybdenum (Mo) contents (The design content was 0, 2, 3.3 and 4.5wt.%, respectively) were deposited using the flux-cored wire by means of metal active gas arc welding. The effects of Mo on the refinement of microstructures, eutectic microstructure changes and improvement of wear resistance were investigated. The main results were shown as follows:the added Mo could increase the volume fraction of eutectic microstructure and reduce the size of coarse primary austenite as well as the volume fraction.The carboboride of M3(B,C) could be observed in hypoeutectic Fe-Cr-B-C hardfacing alloys at the Mo design content of ≤2.0 wt.%, while that of M23(B,C)6 was formed when 3.3 wt.% Mo was added.Additionally, the wear resistance of alloys was increased with the increase in Mo content.Specifically, the highest wear resistance of alloys was achieved at 4.5wt.% Mo design content, which was 113.7% higher than that in alloys without Mo.