Effect of boron on microstructure and properties of high-boron iron-based alloy by plasma transferred arc

The iron-based composite materials of Fe-Cr-BC hardfacing alloys were deposited on the surface of 20g steel by using plasma transferred arc(PTA).The effect of different B contents on microstructure and properties of surfacing layer was investigated by means of the X-ray diffraction(XRD),optical microscope(OM),scanning electron microscope(SEM),Rockwell hardness tester and wet sand abrasion tester.The result shows that the microstructure of the surfacing layer consists of supersaturated α-Fe dendrite solid solution,eutectic boride and carbides.The hard phases in the surfacing layer include Cr₂B,CrB₂,Fe₂B,Cr₇C₃ and B₄C etc.The amount of borides significantly increased with B content increasing,and the hardness and wear resistance of surfacing layer reached optimum value when B contents reached 5%.The hardness is 66.1 HRC and the weight reduction is 0.383 g.The wear resistance of surfacing layer decreased with the amount of boron further increasing.