硼化物强化铁基堆焊合金显微组织与耐磨性

Microstructure and wear resistance of Fe-based hardfacing alloys reinforced by borides

为了提高在严峻工况条件下工作的机械零件的耐磨性,采用等离子弧堆焊技术,制备硼化物强化铁基堆焊合金。借助OM,SEM和XRD等分析手段对合金组织和硼化物相形貌进行分析,并与未加入硼的Fe-Cr-C的堆焊合金进行对比。结果表明:堆焊合金中加入w(B)4.5%可改变基体的组织组成及硼化物的数量和分布形态,从而改善耐磨性。硼化物由大量菊花状M23(C,B)6和少量块状M7(C,B)3相组成,BC4与Cr2B的数量较少。耐磨粒磨损试验结果表明:堆焊合金的耐磨性随着硼含量的增加而先增大后下降,加入w(B)4.5%的堆焊层中形成的大量高硬度硼化物分布在具有较高强韧性的马氏体和奥氏体基体上,使其具有最佳的耐磨性,其磨损量仅为未加入硼时的1/6。

In order to improve the wear resistance of parts of machines in enviroments where they undergo severe conditions,Fe-based hardfacing alloy reinforced with borides were prepared under plasma transferred arc weld surfacing process(PTA).The microstructure and borides morphology were investigated by means of OM,SEM and XRD,which was compared to the Fe-Cr-C hardfacing alloy.The results showed that the microstructure of the matrix and contents and distribution were changed as a result of the addition of 4.5% B in hardfacing alloys,which led to the improvement of wear resistance significantly.The borides consisted of high volume fraction of rosette M 23(C,B) 6 and little volume fraction of blocky M 7(C B) 3,the content of BC 4 and Cr 2 B was very little.The abrasion experimental results showed that the wear resistance firstly increased and afterwards decreased as the B content increased,the microstructure characteristic with a high volume fraction of borides with high microhardness were distributed in the martensite and austenite matrix with high strength and toughness as the addition of 4.5%B in Fe-Cr-C hardfacing alloy,which suggested that the hardfacing layers had a excellent wear resistance and its abrasion mass was only 1/6 of the hardfacing alloy with no addition of B.