目的 通过在超低碳Cr19Ni10不锈钢堆焊合金中加入稀土氧化物La2O3，细化其微观组织，获得力学性能、耐腐蚀性能和耐磨性能等综合性能优良的堆焊合金层。方法 采用添加La2O3的超低碳Cr19Ni10不锈钢焊条制备了四种不锈钢堆焊合金。采用X射线荧光光谱、红外碳硫分析仪和X射线衍射分析仪，对堆焊合金层的元素组成和相组成进行了测定。采用金相显微镜和晶粒度统计软件，对堆焊合金层的微观组织形貌进行观察，并对晶粒度进行了统计分析。采用显微维氏硬度计和纳米压痕仪对堆焊合金层的硬度和杨氏模量进行了测定。采用电化学工作站和CSM摩擦磨损试验机对堆焊合金层的耐腐蚀性能和耐磨性能进行了评价，并且采用白光共聚焦显微镜对磨损后的磨痕形貌和尺寸进行了观察和测定。采用二维晶格错配度理论，对La2O3/γ-Fe界面间的晶格错配关系进行了计算。结果 在堆焊合金层中加入La2O3，随着La2O3加入量的增加，堆焊合金层奥氏体晶粒细化越明显。当La2O3的添加量由0%增加至1.5%时，奥氏体晶粒平均面积由400 μm²减少为210 μm²。堆焊合金层加入La2O3，可以明显提高其力学性能、耐腐蚀性能和耐磨损性能。当La2O3的添加量由0%增加至1.0%时，堆焊合金层的微观硬度由180HV增加到225HV，宏观硬度由125HBS增加到150HBS，杨氏模量由186 GPa左右增加到217 GPa，腐蚀电位由?0.4 V增加到?0.25 V，磨痕深度由50 μm减小到10 μm。La2O3(001)面和γ-Fe(110)面的二维晶格错配度为8.7%(<12%)，说明La2O3可以作为γ-Fe的中等有效异质形核基底，从而细化了堆焊合金层中的奥氏体晶粒。结论 La2O3可以有效地细化奥氏体晶粒，改善堆焊合金层的力学性能，提高其耐腐蚀和耐磨损性能。但是，La2O3加入量存在一个最佳值，当La2O3的加入量为1.0%时，堆焊合金层的综合性能最好。

The work aims to obtain the hardfacing alloy with excellent overall performance including mechanical property, corrosion resistance, wear resistance, etc., by adding rare earth oxide La2O3 into ultra-low carbon Cr19Ni10 stainless steel hardfacing alloy to refine the microstructure. Four kinds of stainless steel hardfacing alloys were prepared with ultra-low carbon Cr19Ni10 stainless steel electrode containing rare earth oxide La2O3. The elements and phase composition of hardfacing alloy layers were measured by X-ray fluorescence spectrum, infrared carbon-sulfur analyzer and X-ray diffraction analyzer. The microstructure and grain size of hardfacing alloy layers were observed and analyzed by metallographic microscope and grain size statistical software. The hardness and Young’s modulus were measured systematically by microvickers hardness tester and nano-indentation instrument. The corrosion resistance and wear resistance were investigated by electrochemical workstation and CSM friction wear tester, and the corresponding morphology as well as the size of wear marks was observed and measured by white light confocal microscope. The lattice mismatch relationships between La2O3/γ-Fe interface were calculated by Bramfitt two-dimensional lattice mismatch theory. When La2O3 additives were added into the hardfacing alloy layer, with the increase of La2O3 addition, the austenite grain in the hardfacing alloy layer was significantly refined. When the addition of La2O3 increases from 0wt% to 1.5wt%, the average austenite grain area was decreased from 400 μm2 to 210 μm2. The mechanical properties, corrosion resistance and wear resistance of La2O3 added hardfacing alloy layers were obviously improved. When the addition of La2O3 increases from 0wt% to 1.0wt%, the microhardness of hardfacing alloys increased from 180HV to 225HV and macroscopic hardness increased from 125HBS to 150HBS. Young’s modulus increased from about 186 GPa to 217 GPa. The corrosion potential increased from ?0.4 V to ?0.25 V. The abrasion depth was reduced from 50 μm to 10 μm. The 2D lattice mismatch between La2O3(001) and γ-Fe(110) was 8.7% (<12%), which indicated that La2O3 could act as a medium effective heterogeneous nucleated substrate of γ-Fe. Therefore, austenite grains in hardfacing alloy layers could be refined. La2O3 can effectively refine austenite grains, improve the mechanical properties of hardfacing alloys, and enhance their corrosion and wear resistance. Moreover, there is an optimal value of La2O3 addition, and the best comprehensive performance can be obtained when the La2O3 addition is 1.0wt.%.