目的 研究稀土氧化物 Y2O3 对粒状贝氏体堆焊金属相转变以及力学性能的影响。 方法 采用金相显微镜和场发射扫描电镜对堆焊金属的微观组织进行观察,采用金相显微镜观察并统计出奥氏体晶粒度,采用 XRD 对堆焊金属表面物相进行测定,采用显微硬度计和电子万能试验机测量不同 Y2O3 质量分数堆焊金属的硬度和拉伸性能,采用透射电子显微镜对堆焊金属微观结构进行表征。 结果 Y2O3 能够有效细化堆焊金属的初生奥氏体晶粒,尺寸由 51. 2 μm 减小到 40. 1 μm,大块先共析铁素体尺寸明显减小,组织分布均匀,且 M/ A 岛弥散分布。 堆焊金属中残余奥氏体相数量随着 Y2O3 质量分数的增加而逐渐降低,马氏体相体积分数增加。 Y2O3 的加入明显提升堆焊金属的力学性能,显微硬度由(272±13)HV 提升至(312±8)HV;抗拉强度由(764±10) MPa 提升至(885±12) MPa,且延伸率增加了 4% 。 结论Y2O3 的加入能够细化堆焊金属的初生奥氏体晶粒,促进形成均匀细化的粒状贝氏体组织, M/ A 岛的数量逐渐增加,且 M/ A 岛中马氏体相数量增加,粒状贝氏体堆焊金属的力学性能显著提高。

Objective To investigate the effects of Y2O3 additive on the microstructure and mechanical property of granular bainite hardfacing alloy. Methods The microstructures of the hardfacing alloy with different Y2O3 additives were observed using optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The phase structures of the hardfacing alloys were determined using X-ray diffraction. The hardness, tensile property and abrasive resistance of the hardfacing alloys with different Y2 O3 additions were determined. Results The results showed that the primary austenite in the hardfacing alloy could be refined by Y2 O3 additive. The grain size of primary austenite decreased from 51. 2 μm to 40. 1 μm with the increase of Y2 O3 addition. Meanwhile, the size of proeutectoid ferrite (PF) decreased significantly and the faction of the bainite increased, so the M / A island could be distributed uniformly. The XRD analysis showed that the fraction of martensite increased while that of retained austenite decreased with the increase of Y2 O3 addition. TEM results showed that large number of dislocation martensite was transformed in M / A. The Y2 O3 additive could improve the hardness, strength and plasticity of the hardfacing alloys. With the increase of Y2 O3 addition, the hardness increased from (272±13)HV to (312±8)HV, the tensile strength increased from (764±10) MPa to (885±12) MPa and the elongation increased by 4% . Conclusion The grain size of primary austenite decreased with the increase of Y2 O3 addition. Meanwhile, the PF was refined significantly and M / A islands distributed uniformly. The fraction of martensite increased and the RA decreased with the increase of Y2 O3 addition. The mechanical property of the hardfacing alloy with Y2 O3 additive was improved.