目的 研制一种新型含氧化镧（La2O3）堆焊装甲车履带用药芯焊丝，通过细化堆焊层合金的微观组织，提高堆焊层合金的耐磨性。方法 采用堆焊的方法制作堆焊层合金，采用金相显微镜观察了其表面显微组织，并测定了其表面洛氏硬度和耐磨性。结果 堆焊层合金微观组织由粒状贝氏体、马氏体和残余奥氏体组成。未加氧化镧的堆焊层合金初生奥氏体晶粒粗大，其平均尺寸在42 μm，耐磨性为6000 min/g；当药芯焊丝中加入质量分数为2.5%的氧化镧之后，堆焊层合金的奥氏体晶粒尺寸最小，其平均尺寸为36 μm，耐磨性为12 300 min/g。铝酸镧（LaAlO3）的（001）面与奥氏体（100）面之间的二维错配度为3.81%。结论 铝酸镧作为γ-Fe的异质形核核心最有效，说明堆焊层合金中铝酸镧可以使初生奥氏体的晶粒尺寸得到细化，从而改善了履带堆焊层合金的耐磨性。

The work aims to develop a novel flux-cored wire with La2O3 for hardfacing armored car crawler belt and improve wear resistance of the hardfacing alloy layer by refining the microstructure. The hardfacing alloy layers were deposited by means of automatic open arc surfacing welding method. The microstructure was observed by using an optical microscopy. Meanwhile, Rockwell hardness and wear resistance of the hardfacing alloy surface were measured. The microstructure of the hardfacing alloy contained bainite, martensite and residual austenite. The average size of primary austenite was about 42 μm and mass loss of the La2O3-free alloy 6000 min/g. With La2O3 added, the average size of primary austenite was about 36 μm and mass loss 12300 min/g. The two-dimensional lattice misfit between the (001) face of LaAlO3 and (100) face of austenite was 3.81%. With La2O3, LaAlO3 as most effective γ-Fe heterogeneous nuclei, the primary austenite is refined and thereby the wear resistance of the hardfacing alloy layer can be improved as well.