Fe-2.2Nb-0.9Ni-1.0C-xB堆焊合金组织与耐磨性

Microstructure and abrasive wear resistance of Fe-2.2Nb-0.9Ni-1.0C hardfacing alloys

采用CO_2气体保护焊堆焊方法,制备了含不同硼元素含量的Fe-2.2Nb-0.9Ni-1.0C-xB(x=0.5,1.5,2.5,3.5)铁基堆焊合金,利用OM,SEM,XRD等分析方法对堆焊合金的显微组织进行了观察分析,测试了堆焊合金的硬度及耐磨料磨损性能,分析了硼含量对堆焊合金耐磨性的影响。结果表明,随着硼元素的增多,堆焊合金宏观硬度值逐渐升高并稳定在HRC 62左右,而耐磨料磨损性能呈现先升后降的趋势;当硼含量为2.5%(质量分数)时,合金组织中开始析出Fe_2B相,其耐磨料磨损性能为最优;当硼含量达到3.5%(质量分数)时,堆焊合金的磨损机理开始由塑性变形引起的犁沟和切削机制转变为由断裂机制引起的过共晶Fe_2B相脱落。

The Fe-2.2Nb-0.9Ni-1.0C alloy with B additions was deposited by CO2 gas shielded welding method.The microstructure of the hardfacing alloy was investigated by optical microscopy(OM),scanning electron microscopy(SEM),X- ray diffraction(XRD).The hardness and abrasive wear properties of hardfacing alloy was investigated by varying boron concentration.It was found that the hardness value of the hardfacing alloy increases firstly and then stabilizes at about HRC 62 with increasing boron concentration,while the abrasive wear resistance of the hardfacing alloys will change at 2.5wt.%boron.If boron concentration is less than 2.5wt.%,the abrasive wear resistance is improved almost linearly.While it will be found that the primary Fe2 B started to precipitate at boron concentration higher than 2.5wt.%,and the highest wear resistance can be achieved.The mechanism of the abrasive wear resistance changed at 3.5wt.%boron.If boron concentration is less than3.5wt.%,the mechanism of the abrasive wear resistance is mainly plough or micro- cutting induced by plastic deformation mechanisms.At boron concentration higher than 3.5wt.%,the mechanism of the abrasive wear resistance will change into the brittle peeling of the primary Fe2 B phase.