磁控状态下Fe90堆焊层显微组织对力学性能的影响

为了研究直流横向磁场对Fe90堆焊层组织和性能的影响，在Fe90自熔堆焊合金的等离子弧堆焊过程中引入直流横向磁场，采用洛氏硬度仪、磨损试验机对不同规范下试样的硬度、耐磨损性进行测试，采用OM及SEM对堆焊层进行显微组织分析，进而揭示外加磁场对堆焊层性能的作用机理.结果表明，施加磁场的堆焊层要比无磁场作用的堆焊层硬度高、耐磨性好；当堆焊电流为I=180 A，磁场电流为I_m=3 A时，堆焊层性能取得最佳值，其磨损量为0.4218 g，表面硬度HRC为72.1.外加磁场提高堆焊层性能的主要原因是电弧和熔池在磁场作用下运动状态发生改变，改善了堆焊层组织，使堆焊层的组织由柱状晶转化为等轴晶并细化晶粒，进而提高堆焊层的综合力学性能.

Effect of microstructure on mechanical properties of Fe90 surfacing layer at magnetic control state

In order to research the influence of direct current （DC） transverse magnetic field on microstructure and properties of Fe90 surfacing layer, the DC transverse magnetic field was introduced in the process of plasma arc surfacing for Fe90 self fluxing surfacing alloy. The hardness and wear resistance of the specimens with different specifications were tested with Rockwell hardness tester and wear tester, and the microstructure of surfacing layer was observed with optical microscope （OM） and scanning electron microscope （SEM）. Furthermore, the action mechanism of external magnetic field on the properties of surfacing layer was revealed. The results indicate that compared with the surfacing layer without external magnetic field, the surfacing layer with magnetic field exhibits higher hardness and better wear resistance. When the surfacing current is 180 A and magnetic field current is 3 A, the optimal properties of surfacing layer is acquired, where the wear loss of surfacing layer is 0. 4218 g and the surface hardness is 72.1 HRC. The main reason for the improvement in the properties of surfacing layer by external magnetic field is that the motion state of arc and molten pool changes under the action of magnetic field, and the microstructure of surfacing layer gets improved. The microstructure of surfacing layer changes from columnar crystal to equiaxed crystal, and the grains get refined, and thus, the comprehensive mechanical properties of surfacing layer are enhanced.