硼对等离子熔覆高硼铁基合金组织和性能的影响

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

采用等离子弧熔覆技术在20g钢表面堆焊Fe-Cr-B-C系的铁基复合材料,利用X射线衍射(XRD),光学显微镜(OM),扫描电镜(SEM),洛氏硬度计及湿砂磨损试验机等试验设备进行检测、试验,研究不同硼加入量对熔覆层显微组织与性能的影响规律.结果表明,熔覆层显微组织由过饱和α-Fe枝晶固溶体、枝晶间硼化物共晶组织以及碳化物等组成;熔覆层中硬质相主要有Cr2B,CrB2,Fe2B,Cr7C3,B4C等;随着硼含量的增加,硼化物明显增多,当硼添加量为5%时熔覆层的硬度及耐磨性达到最佳,其硬度值为66.1 HRC,磨损量仅为0.383 g;继续增加硼的添加量,熔覆层的耐磨性能降低.

The iron-based composite materials of Fe-Cr-B-C 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.